Impact of Regional heterogeneity of RSV infection prophylaxis on bronchiolitis in Italy

Impact of Regional heterogeneity of RSV infection prophylaxis on bronchiolitis in Italy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of Regional heterogeneity of RSV infection prophylaxis on bronchiolitis in Italy Raffaele Badolato, Viola Ceconi, Roberto Bellu', Eugenio Baraldi, and 24 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7938646/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Respiratory syncytial virus (RSV) remains a leading cause of bronchiolitis and hospitalization in infants across Italy, particularly during predictable seasonal outbreaks. With the 2023–2025 RSV seasons marking the first large-scale rollout of the monoclonal antibody nirsevimab, this nationwide observational study evaluated implementation strategies and outcomes across 19 Italian regions. Data were collected through the Italian Society of Pediatrics and the Italian Society of Neonatology, focusing on differences in rollout timing, logistics, and RSV-related hospital and pediatric intensive care unit (PICU) admissions. The results highlighted significant regional heterogeneity. Northern and central regions such as Veneto, Lombardy, and Tuscany initiated prophylaxis earlier and experienced fewer logistical barriers, resulting in marked reductions in RSV hospitalizations - up to 83.7% in Friuli-Venezia Giulia. Conversely, southern and smaller central regions, including Molise, Marche, and Umbria, faced delayed starts, supply shortages, and bureaucratic challenges, leading to more modest decreases. PICU admissions mirrored these trends. Overall, the national introduction of nirsevimab correlated with a significant reduction in RSV-related morbidity, especially in regions with early, well-organized rollouts. Comparative international studies from France, Spain, and Luxembourg reinforce the Italian findings: timely and universal prophylaxis leads to substantial public health benefits. The study concludes that early campaign activation, consistent drug availability, and efficient organization are critical for maximizing the protective effect of RSV immunization. Figures Figure 1 Figure 2 Figure 3 Background Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and the leading cause of hospitalization of children in Italy in the first year of life [ 1 ]. Bronchiolitis is the most common severe manifestation, but RSV infection is associated with recurrent wheezing in infancy, and possibly with an increased risk of developing asthma [ 2 – 4 ]. Because of the lack of effective treatment for RSV bronchiolitis, the reduction of morbidity must rely on preventive measures, and its therapy includes general supportive management to control pulmonary and systemic clinical symptoms [ 5 ]. In Italy, RSV shows clear seasonality, but the timing and intensity vary by region. Nationwide surveillance shows RSV epidemics generally occur from late autumn to early spring, peaking between December and February, with earlier peaks in northern regions and slightly later peaks in the south. In northern and central Italy, RSV activity usually starts in November, peaks in December–January, and ends by March, while in southern Italy, the season can extend into April. A multi-season analysis confirmed that RSV circulation is highly consistent, with yearly epidemics showing limited variability in onset and peak, making seasonally targeted prophylaxis feasible [ 6 ]. In past years, the most effective RSV prevention strategies were hygiene measures and passive immunization with palivizumab for high-risk infants, while vaccines remained experimental until very recently. Early vaccine trials in the 1960s failed due to enhanced disease, but later studies showed subunit vaccines could reduce RSV incidence, though they never reached wide use [ 7 ]. More recently, maternal vaccination and new platforms have been under development [ 8 ]. RSV immune globulin (RSV-IGIV) was one of the first agents shown to reduce the incidence and severity of RSV, but its use declined due to logistical issues [ 9 ]. In particular, Palivizumab (monoclonal antibody) became the standard prophylaxis for high-risk infants (premature, congenital heart disease, bronchopulmonary dysplasia), reducing RSV hospitalizations significantly [ 10 , 11 ]. In lastest years a new generation of long-acting anti RSV mAb has been developed. Nirsevimab is a monoclonal antibody designed to protect infants from RSV (respiratory syncytial virus), and research shows it is effective in reducing severe cases of bronchiolitis caused by RSV. Nirsevimab significantly reduced RSV-related hospitalizations and severe cases of bronchiolitis in healthy infants during their first RSV season [ 12 ]. A pooled analysis found nirsevimab lowered the incidence of medically attended RSV lower respiratory tract infections and hospitalization compared to placebo, showing broad protective effects [ 13 ]. Real-world trials showed that even a single intramuscular dose provided protection across an entire RSV season, helping reduce the burden of bronchiolitis in both preterm and full-term infants [ 14 – 16 ]. In Valle d'Aosta a recent Study demonstrated that universal prophylaxis with nirsevimab significantly reduced RSV-related hospitalizations in neonates, with no hospitalizations in the treated group compared to 8.3% in the untreated group [ 17 ]. In Tuscany, a real-world cost-benefit analysis assessed various nirsevimab prophylaxis strategies, finding that universal prophylaxis targeting all infants during their first RSV epidemic season substantially reduced hospitalization burdens without increasing economic pressure on the healthcare system [ 18 ]. Methods This descriptive retrospective study was conducted in 19 Italian regions through a collaboration between the Italian Society of Pediatrics (SIP) and the Italian Society of Neonatology (SIN). The 19 regional branches of SIP collected information from their respective regions regarding the implementation methods of the RSV infection prophylaxis campaign. In each region, one or more sentinel hospitals were identified:Giuseppe Mazzini hospital (Teramo, Abruzzo), Giovanni XXIII (Bari, Apulia), San Carlo hospital (Potenza, Basilicata), Annunziata hospital (Cosenza, Calabria), Santobono Pausilipon hospital (Napoli, Campania) and all the neonatal intensive care units of Campania, AUSL Bologna (Bologna, Emilia-Romagna), S. Orsola-Malpighi (Bologna, Emilia-Romagna), AUSL Modena (Modena, Emilia-Romagna), Ramazzini Hospital (Modena, Emilia-Romagna), Guglielmo da Saliceto hospital (Piacenza, Emilia-Romagna), Santa Maria della Misericordia hospital (Udine, Friuli-Venezia Giulia), Bambino Gesù hospital (Roma, Lazio), Sant’Andrea hospital (Roma, Lazio), Sant’Eugenio hospital (Roma, Lazio), Umberto I hospital (Roma, Lazio), Giannina Gaslini hospital (Genova, Liguria), Bolognini hospital (Bergamo, Lombardy), Desenzano del Garda hospital (Brescia, Lombardy), Esine hospital (Brescia, Lombardy), Spedali Civili hospital (Brescia, Lombardy), Ca’ Granda hospital (Milano, Lombardy), Fatebenefratelli Sacco hospital (Milano, Lombardy), Giuseppe Fornaroli hospital (Milano, Lombardy), Legnano hospital (Milano, Lombardy), San Paolo hospital (Milano, Lombardy), San Raffaele hospital (Milano, Lombardy), Vizzolo Predabissi hospital (Milano, Lombardy), San Gerardo dei Tintori hospital (Monza, Lombardy), San Matteo hospital (Pavia, Lombardy), Galmarini-Tradate hospital (Varese, Lombardy), Salesi Ancona hospital (Ancona, Marche), Carlo Urbani hospital (Jesi, Marche), Principe di Piemonte hospital (Senigallia, Marche), Madonna del Soccorso hospital (San Benedetto del Tronto, Marche), Mazzoni hospital (Ascoli Piceno, Marche), Augusto Murri hospital (Fermo, Marche), Civitanova Marche hospital (Civitanova Marche, Marche), Macerata hospital (Macerata, Marche), San Salvatore hospital (Pesaro, Marche), Santa Croce hospital (Fano, Marche), Santa Maria della Misericordia hospital (Urbino, Marche), Antonio Cardarelli hospital (Campobasso, Molise), San Timoteo hospital (Campobasso, Molise), Ferdinando Veneziale hospital (Isernia, Molise), Cesare Arrigo hospital (Alessandria, Piedmont), Maggiore hospital (Novara, Piedmont), Giuseppe Brotzu hospital (Cagliari, Sardinia), San Francesco hospital (Nuoro, Sardinia), San Martino hospital (Oristano, Sardinia), Santissima Annunziata hospital (Sassari, Sardinia), Giovanni di Cristina hospital (Palermo, Sicily), Meyer hospital (Firenze, Tuscany), Mugello hospital (Firenze, Tuscany), San Giuseppe hospital (Firenze, Tuscany), Santa Maria Annunziata hospital (Firenze, Tuscany), Cecina hospital (Livorno, Tuscany), San Luca hospital (Lucca, Tuscany), Versilia hospital (Lucca, Tuscany), Apuane hospital (Massa-Carrara, Tuscany), Santa Chiara hospital (Pisa, Tuscany), San Jacopo Hospital (Pistoia, Tuscany), Bolzano Central hospital (Bolzano, Trentino-Alto Adige), Bressanone hospital (Bolzano, Trentino-Alto Adige), Rovereto hospital (Trento, Trentino-Alto Adige), Città di Castello hospital (Perugia, Umbria), Gubbio e Gualdo Tadino hospital (Perugia, Umbria), San Giovanni Battista (Perugia, Umbria), Santa Maria della Misericordia hospital (Perugia, Umbria), Santa Maria della Stella hospital (Terni, Umbria), Santa Maria hospital (Terni, Umbria), all the hospitals of Veneto. These hospitals collected data on RSV bronchiolitis-related hospitalizations in pediatric, neonatology, or pediatric intensive care units from November 2023 to March 2024, and again from November 2024 to March 2025, through the hospital coding system used for RSV bronchiolitis case classification. For each region, we reported the start date of prophylaxis campaign during the epidemic season 2024–2025, children eligible for immunization (born during the epidemical season from October 2024b to March 2025 or ot-of-season born), major issues encountered during this first campaign. Afterwards we collected for each region the following data: number of hospital admissions for RSV bronchiolitis, month by month from October 2023 to March 2024 and from October 2024 to March 2025, through the sum of admissions in the sentinel hospitals of the region; cumulative number of admissions for RSV bronchiolitis in intensive care units from October 2023 to March 2024 and from October 2024 to March 2025, through the sum of PICU admissions in the sentinel hospitals of the region; percentage reduction in hospital admission for RSV bronchiolitis in epidemic season 2024- 2025 compared to previous epidemic season 2023–2024. Results We have collected the vaccination and immunization recommendations from 19 Italian regions and analyzed differences and outcomes. The rollout of nirsevimab prophylaxis against RSV in Italy has been marked by wide heterogeneity among regions, with differences in start dates, organizational barriers, and drug availability. Some regions were able to launch their campaigns early and without significant obstacles, while others faced delays, shortages, and bureaucratic challenges that slowed implementation (Table 1 ). Table 1 Heterogeneity of nirsevimab prophylaxis among Italian regions Region Campaign Start Date Issues Abruzzo 07-Jan-25 Delayed activation, tender process. Apulia 12-Nov-24 Short periods of drug unavailability. Basilicata 06-Dec-24 Not specified. Calabria 16-Dec-24 Difficult coverage of previously born infants, low-dose availability. Campania 11-Nov-24 Bureaucratic difficulties in entering newborns into the platform. Emilia-Romagna 28-Oct-24 None. Friuli-Venezia Giulia 04-Nov-24 Initial difficulties in obtaining doses, then regular start. Lazio 11-Dec-24 Late start and limited dose availability. Liguria 05-Dec-24 Drug availability/number of doses. Lombardy 01-Nov-24 None. Marche 01-Dec-24 Delayed drug availability. Molise 20-Nov-24 Drug unavailable from the second half of December 2024. Piedmont 01-Nov-24 None. Sardinia 16-Dec-24 Lack of availability of 100 mg vials. Sicily Not specified. Tuscany 04-Nov-24 None. Trentino-Alto Adige 28-Oct-24 None. Umbria 20-Jan-25 Regional Council resolution at the end of November 2024. Delay in doses. Veneto 04-Nov-24 None. In Northern and Central Italy, several regions demonstrated strong preparedness. Emilia Romagna and Trentino Alto Adige were among the first to start at the end of October 2024, followed closely by Lombardy, Piedmont, Tuscany, and Veneto in early November. These regions largely reported no major issues, indicating effective planning and coordination. Friuli Venezia Giulia also began in early November, experiencing only brief difficulties in obtaining doses before establishing regular supply. By contrast, other regions encountered interruptions or barriers that slowed the campaign. Apulia, starting in mid-November, faced short periods of unavailability. Marche launched at the beginning of December but was affected by the delayed delivery of doses. Liguria and Lazio, both beginning in December, struggled with limited availability, while Campania dealt with bureaucratic obstacles in enrolling newborns into the digital platform. Calabria and Sardinia, also starting in December, reported more severe problems, including difficulties in covering infants born before the campaign began, insufficient doses, and lack of 100 mg vials. Molise, despite starting in late November, experienced a complete absence of supply from January onward. Other regions began later still. Basilicata activated prophylaxis in December but did not provide specific details on difficulties. Abruzzo delayed its start until early January 2025 due to tender procedures, and Umbria only launched in late January, slowed by a late Regional Council resolution and limited drug availability. Report on RSV Admissions in Italian Hospitals (2023–2024 vs. 2024–2025 seasons) Hospital admissions of neonates and infants with RSV infections during the last two seasons show a marked overall decline across Italian regions, although the extent of reduction varied significantly from North to South. The data indicate both widespread decreases in case burden and striking regional differences in the magnitude of reduction (Table 2 ). Table 2 REGION Neonatology & pediatrics admissions 2023–2024 Neonatology & pediatrics admissions 2024–2025 Abruzzo 79 47 -40.5% Apulia 118 58 -50.8% Basilicata 83 53 -36.1% Calabria 32 9 -71.8% Campania 555 336 -39.4% Emilia-Romagna 519 305 -41.2% Friuli-Venezia Giulia 98 16 -83.7% Lazio 438 294 -32.9% Liguria 227 120 -47.1% Lombardia 832 300 -63.9% Marche 210 179 -14.8% Molise 48 37 -22.9% Piemonte 148 53 -64.2% Sardinia 158 75 -52.3% Sicilia 1529 822 -46.2% Toscana 483 118 − 75.6% Trentino-Alto Adige 154 91 -40.9% Umbria 179 146 -18.4% Veneto 1203 379 -68.5% Several regions recorded very steep declines. Friuli-Venezia Giulia experienced the most dramatic drop, from 98 admissions in 2023–2024 to only 16 in 2024–2025, corresponding to nearly 84% fewer cases. Lombardy, one of the most populous regions, saw a substantial reduction of nearly two-thirds, moving from over 800 cases to 300. Piedmont, Tuscany and Veneto also showed pronounced declines, with reductions above 64%, 76% and 68% respectively. Regions in the South also reflected meaningful decreases, though with different intensities. Sicily, which had by far the highest burden in the previous season with more than 1,500 admissions, reported a 46% decline but still accounted for over 800 cases in 2024–2025, remaining the region with the heaviest caseload. Campania and Apulia also showed decreases of around 40–50%, while Calabria achieved a more dramatic reduction of almost 72%, moving from 32 cases down to only 9. But, this is the result of analysis a single hospital from the region. Sardinia’s admissions dropped by over half, confirming a significant downward shift. In Central Italy, Lazio recorded nearly a 33% decrease, falling from 438 admissions to 294. Marche saw only a modest reduction of about 15%, with 179 cases still reported. Umbria and Molise also showed more contained decreases, of 18% and 23% respectively, suggesting that RSV activity remained relatively stable compared to the stronger declines observed elsewhere. Regions of the North generally saw consistent reductions. Emilia Romagna, with over 500 cases in 2023–2024, reported a 41% decline to 305 admissions. Liguria recorded a nearly 47% decrease. Trentino Alto Adige showed a 41% reduction, while Basilicata, despite lower absolute numbers, saw a significant decline of 36%. Report on PICU Admissions for RSV in Italian Regions (2023–2024 vs. 2024–2025 seasons) The number of admissions to Pediatric Intensive Care Units (PICU) for RSV infection decreased substantially across most Italian regions between the 2023–2024 and 2024–2025 seasons, though with notable variability in magnitude and distribution (Table 3 ). Table 3 REGION PICU admissions 2023–2024 TI 2024–2025 Changes PICU admissions Abruzzo 4 4 0% Apulia Nd Nd Basilicata 11 3 73% Calabria 3 0 100% Campania 41 23 44% Emilia-Romagna 41 19 54% Friuli-Venezia Giulia 61 6 90% Lazio 59 17 72% Liguria Nd Nd Lombardy 127 38 70% Marche 10 2 80% Molise 0 0 Piedmont 13 7 46% Sardinia 9 2 78% Sicily 93 25 73% Tuscany 66 12 82% Trentino-Alto Adige 14 3 79% Umbria 25 12 52% Veneto 116 27 77% Regions with the highest case burden in the previous season showed marked reductions. Lombardy dropped from 127 admissions to 38, representing a 70% decrease, while Sicily, with 93 admissions previously, recorded a 73% reduction to 25. Friuli Venezia Giulia showed one of the most dramatic improvements, falling from 61 to just 6 cases, equivalent to a 90% decrease. Emilia Romagna also demonstrated strong progress, cutting admissions by more than half, from 41 to 19. Campania mirrored this trend, moving from 41 to 23 admissions, a 44% reduction. Other regions with moderate burdens in 2023–2024 also reported clear declines. Tuscany reduced admissions by 82%, from 66 to 12. Veneto fell from 116 to 27, an 77% reduction. Trentino Alto Adige dropped by 79%, from 14 to 3 Umbria, which had reported 25 admissions in the previous season, nearly halved the number to 12. Piemonte reduced admissions from 13 to 7, a 46% decline. Sardinia reported a 78% reduction, from 9 admissions down to 2. Smaller regions with limited admissions showed mixed patterns. Basilicata fell sharply from 11 to 3 cases, a 73% reduction. Marche recorded a fall from 10 to 2, equivalent to an 80% decrease. Calabria registered no cases in the 2024–2025 season compared to 3 previously, reflecting a complete elimination of PICU admissions. Abruzzo was an exception, with 4 admissions in both seasons, showing no change. Molise continued to report no admissions in either season. Data were not available for Liguria and Apulia, preventing direct comparison. Regional implementation of nirsevimab prophylaxis in Italian regions In Italy, the regional implementation of nirsevimab prophylaxis against RSV bronchiolitis showed clear variability in both timing and effectiveness, which can be grouped into three main performance clusters. We have classified the regions on the basis of their policies and of the disease outcome (Table 4 ). High-performing regions (group 1) included Calabria, Friuli-Venezia Giulia, Lombardy, Piedmont, Tuscany and Veneto which achieved the strongest outcomes, with more than a 60% reduction in hospital admissions for bronchiolitis (Fig. 1 ). These successes were largely due to an early start of prophylaxis, often in October 2024, combined with excellent coordination between neonatology units, pediatric services, and pharmacies. In these regions, coverage was broad, including infants born outside the main epidemic window, and no major drug supply constraints were reported. The result was not only a sharp reduction in hospitalizations but also a significant drop in pediatric intensive care unit (PICU) admissions. These regions represent a benchmark model for early activation, good planning, and seamless organizational integration. Table 4 Group Criteria Regions Summary Group 1 Decrease in hospital admission for RSV bronchiolitis > 60% Calabria, Friuli-Venezia Giulia, Lombardy, Piedmont, Tuscany, Veneto High-performing regions with, in most cases, early and smooth implementation, no reported major issues, strongly reduction in PICU admissions Group 2 Decrease in hospital admission for RSV bronchiolitis from 30% to 59% Abruzzo, Apulia, Basilicata, Campania, Emilia-Romagna, Lazio, Liguria, Sardegna, Sicily, Trentino-Alto Adige Decent impact on admissions, though not as consistent, prophylaxis started in November/January or limited immunization of out-of-season born, mild to moderate issues Group 3 Decrease in hospital admission for RSV bronchiolitis < 25% Umbria, Molise, Marche Delayed activation and/or drug shortages likely limited the effectiveness of the intervention Moderately effective regions (group 2), included Abruzzo, Apulia, Basilicata, Campania, Emilia-Romagna, Lazio, Liguria, Sardegna, Sicily, and Trentino-Alto Adige, saw reductions of 30–59% in RSV-related hospitalizations (Fig. 2 ). While the intervention was still effective, its impact was less consistent compared to Group 1. In several cases, prophylaxis started late (November or even December 2024), while in others coverage was more limited, particularly for infants born out of the epidemic peak season. Organizational barriers also played a role, including fragmented integration between hospitals and community healthcare, variable communication efforts towards families, and temporary but impactful drug supply shortages. The overall impact was still positive, but these regions would benefit from better planning and stronger logistical coordination to match the outcomes of the top-performing group. While other Regions showed delayed or ineffective implementation including (Group 3) Umbria, Molise, and Marche that experienced the least impact, with little or no improvement in hospitalization rates (reductions below 25%). Here, prophylaxis was generally launched only in December 2024 or January 2025, which coincided with or followed the peak of RSV infections, leaving many newborns unprotected (Fig. 3 ). Additional challenges included procurement delays and limited coordination across local health authorities. As a result, both hospital admissions and PICU admissions remained largely unchanged. Discussion The implementation of nirsevimab across Italy revealed marked regional heterogeneity, mirroring patterns described in recent international studies. Northern and Central areas, such as Emilia Romagna, Lombardy, Piedmont, Tuscany, Veneto, and Trentino Alto Adige, launched campaigns earlier and with fewer logistical barriers, while Southern regions, including Calabria, Campania, Sardinia, and Molise, faced delays and organizational obstacles, often compounded by limited drug supply. These difficulties echo findings from Spain and France, where consistent drug availability and efficient planning were critical to achieving strong protective effects [ 19 ] [ 20 ]. In Catalonia and Andorra, systematic early immunization led to clear reductions in RSV hospitalizations, while in Paris, case-control analyses confirmed protection against bronchiolitis admissions. Additional evidence from French PICUs demonstrated an estimated 75.9% effectiveness in preventing severe RSV cases [ 21 ], and Andalusian data confirmed that timely prophylaxis reduced both hospitalizations and intensive care admissions [ 22 ]. Findings from Luxembourg similarly showed that population-wide prophylaxis substantially lowered RSV hospitalizations during the 2023/24 season [ 23 ]. Together, these data highlight how early readiness, reliable supply, and coordinated execution consistently translate into measurable population benefits — an experience echoed in Italy, where regions with earlier activation were better able to avoid shortages and maintain smoother rollouts. In parallel, data on RSV-related hospitalizations in Italy showed a nationwide downward trend, with the sharpest declines in Friuli Venezia Giulia, and more modest decreases in Marche, Molise, and Umbria. Some regions, such as Sicily, Campania, and Lombardy, continued to carry a high absolute burden, likely reflecting demographic factors and differences in preventive implementation. Nevertheless, reductions in pediatric intensive care unit (PICU) admissions were consistent across most regions, with the largest relative decreases observed in Friuli Venezia Giulia, Tuscany, Calabria and Marche. Larger regions such as Lombardy, Emilia Romagna, and Sicily still sustained the highest absolute numbers, but all demonstrated marked improvements compared to the prior season, suggesting a meaningful nationwide decline in severe RSV cases. A combined analysis of prophylaxis rollout, pediatric hospital admissions, and PICU data stratified Italian regions into three performance groups. Group 1 ( Calabria, Friuli-Venezia Giulia, Lombardy, Piedmont, Tuscany and Veneto) represented high-performing areas, marked by early campaign activation, absence of major logistical barriers, and reductions in hospital burden often exceeding 60%. Group 2 ( Abruzzo, Apulia, Basilicata, Campania, Emilia-Romagna, Lazio, Liguria, Sardinia, Sicily, trentino-Alto Adige) began later and faced operational hurdles such as intermittent shortages or bureaucratic delays, yet still achieved30–60% reductions, albeit less consistently. Group 3 ( Marche, Molise, Umbria) experienced late activation and limited impact, with reductions generally below 25%. Taken together, these findings underscore the importance of early planning, reliable supply chains, and organizational efficiency in maximizing the impact of nirsevimab prophylaxis. Regions that were able to start early and operate smoothly achieved the most substantial reductions in both pediatric and intensive care admissions. Conversely, delayed or troubled rollouts yielded only modest benefits, reinforcing the time-sensitive nature of RSV prevention. Declarations This study was conducted through the analysis of hospital discharge forms (SDOs) for bronchiolitis and therefore, did not require access to individual patient data. The study is exclusively based on administrative datasets. Ethical approval and Consent to Participate declarations: not applicable. Consent for publication: Not applicable Funding. This study has been funded by the Società Italiana di Pediatria (SIP). Authors' contributions. RB has designed the study and written the article, RA has designed the study, all the other Authors have collected and processed the data provided by hospitals and regional health authorities for this study. All authors read and approved the final manuscript. Acknowledgements. We would like to thank all the regional and hospital authorities who have supported the data collection. Availability of data and materials. The datasets during and/or analysed during the current study are available from the corresponding author on reasonable request Competing interests. The authors declare that they have no competing interests. References Azzari C, Baraldi E, Bonanni P, Bozzola E, Coscia A, Lanari M et al. Epidemiology and prevention of respiratory syncytial virus infections in children in Italy. Ital J Pediatr [Internet]. 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11:50:09","extension":"html","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":131580,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7938646/v1/4b95a3ed5f4dfc02c033db73.html"},{"id":96283729,"identity":"c7e01249-8c16-4a45-b515-e6e04bf66f95","added_by":"auto","created_at":"2025-11-19 11:50:08","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":77056,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eHigh-performing regions with early and smooth implementation, resulting in substantial reductions in hospital burden.\u003c/strong\u003e On each graph are show the admissions trends for RSV bronchiolitis during the epidemic season (from October to March) by comparing 2023-2024 and 2024-2025 two-year period, in the sentinel hospitals of the region.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7938646/v1/947aefaba1140122bd1a8722.png"},{"id":96283732,"identity":"4efe53c9-5e06-4b01-bbed-62cbd9641ccb","added_by":"auto","created_at":"2025-11-19 11:50:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":127568,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRegions with some operational challenges; decent impact on admissions, though not as consistent. \u003c/strong\u003eOn each graph are show the admissions trends for RSV bronchiolitis during the epidemic season (from October to March) by comparing 2023-2024 and 2024-2025 two-year period, in the sentinel hospitals of the region.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7938646/v1/6bba1b43e24390ff1351085c.png"},{"id":96283730,"identity":"31d4fb19-3163-4a1b-9fa9-86ccd2a9d0a3","added_by":"auto","created_at":"2025-11-19 11:50:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":56096,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRegions with delayed activation and/or drug shortages likely limited the effectiveness of the intervention.\u003c/strong\u003e On each graph are show the admissions trends for RSV bronchiolitis during the epidemic season (from October to March) by comparing 2023-2024 and 2024-2025 two-year period, in the sentinel hospitals of the region.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7938646/v1/432ba3d975c229ab294ed7ea.png"},{"id":96369199,"identity":"8a98a11b-79af-4b2b-8656-b205f7db635a","added_by":"auto","created_at":"2025-11-20 10:19:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1392951,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7938646/v1/9b27b73e-6759-4c93-a9be-85622dc7dbfc.pdf"}],"financialInterests":"","formattedTitle":"Impact of Regional heterogeneity of RSV infection prophylaxis on bronchiolitis in Italy","fulltext":[{"header":"Background","content":"\u003cp\u003eRespiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and the leading cause of hospitalization of children in Italy in the first year of life [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Bronchiolitis is the most common severe manifestation, but RSV infection is associated with recurrent wheezing in infancy, and possibly with an increased risk of developing asthma [\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Because of the lack of effective treatment for RSV bronchiolitis, the reduction of morbidity must rely on preventive measures, and its therapy includes general supportive management to control pulmonary and systemic clinical symptoms [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn Italy, RSV shows clear seasonality, but the timing and intensity vary by region. Nationwide surveillance shows RSV epidemics generally occur from late autumn to early spring, peaking between December and February, with earlier peaks in northern regions and slightly later peaks in the south. In northern and central Italy, RSV activity usually starts in November, peaks in December\u0026ndash;January, and ends by March, while in southern Italy, the season can extend into April. A multi-season analysis confirmed that RSV circulation is highly consistent, with yearly epidemics showing limited variability in onset and peak, making seasonally targeted prophylaxis feasible [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn past years, the most effective RSV prevention strategies were hygiene measures and passive immunization with palivizumab for high-risk infants, while vaccines remained experimental until very recently. Early vaccine trials in the 1960s failed due to enhanced disease, but later studies showed subunit vaccines could reduce RSV incidence, though they never reached wide use [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. More recently, maternal vaccination and new platforms have been under development [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. RSV immune globulin (RSV-IGIV) was one of the first agents shown to reduce the incidence and severity of RSV, but its use declined due to logistical issues [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In particular, Palivizumab (monoclonal antibody) became the standard prophylaxis for high-risk infants (premature, congenital heart disease, bronchopulmonary dysplasia), reducing RSV hospitalizations significantly [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn lastest years a new generation of long-acting anti RSV mAb has been developed. Nirsevimab is a monoclonal antibody designed to protect infants from RSV (respiratory syncytial virus), and research shows it is effective in reducing severe cases of bronchiolitis caused by RSV. Nirsevimab significantly reduced RSV-related hospitalizations and severe cases of bronchiolitis in healthy infants during their first RSV season [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. A pooled analysis found nirsevimab lowered the incidence of medically attended RSV lower respiratory tract infections and hospitalization compared to placebo, showing broad protective effects [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Real-world trials showed that even a single intramuscular dose provided protection across an entire RSV season, helping reduce the burden of bronchiolitis in both preterm and full-term infants [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In Valle d'Aosta a recent Study demonstrated that universal prophylaxis with nirsevimab significantly reduced RSV-related hospitalizations in neonates, with no hospitalizations in the treated group compared to 8.3% in the untreated group [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In Tuscany, a real-world cost-benefit analysis assessed various nirsevimab prophylaxis strategies, finding that universal prophylaxis targeting all infants during their first RSV epidemic season substantially reduced hospitalization burdens without increasing economic pressure on the healthcare system [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis descriptive retrospective study was conducted in 19 Italian regions through a collaboration between the Italian Society of Pediatrics (SIP) and the Italian Society of Neonatology (SIN). The 19 regional branches of SIP collected information from their respective regions regarding the implementation methods of the RSV infection prophylaxis campaign. In each region, one or more sentinel hospitals were identified:Giuseppe Mazzini hospital (Teramo, Abruzzo), Giovanni XXIII (Bari, Apulia), San Carlo hospital (Potenza, Basilicata), Annunziata hospital (Cosenza, Calabria), Santobono Pausilipon hospital (Napoli, Campania) and all the neonatal intensive care units of Campania, AUSL Bologna (Bologna, Emilia-Romagna), S. Orsola-Malpighi (Bologna, Emilia-Romagna), AUSL Modena (Modena, Emilia-Romagna), Ramazzini Hospital (Modena, Emilia-Romagna), Guglielmo da Saliceto hospital (Piacenza, Emilia-Romagna), Santa Maria della Misericordia hospital (Udine, Friuli-Venezia Giulia), Bambino Ges\u0026ugrave; hospital (Roma, Lazio), Sant\u0026rsquo;Andrea hospital (Roma, Lazio), Sant\u0026rsquo;Eugenio hospital (Roma, Lazio), Umberto I hospital (Roma, Lazio), Giannina Gaslini hospital (Genova, Liguria), Bolognini hospital (Bergamo, Lombardy), Desenzano del Garda hospital (Brescia, Lombardy), Esine hospital (Brescia, Lombardy), Spedali Civili hospital (Brescia, Lombardy), Ca\u0026rsquo; Granda hospital (Milano, Lombardy), Fatebenefratelli Sacco hospital (Milano, Lombardy), Giuseppe Fornaroli hospital (Milano, Lombardy), Legnano hospital (Milano, Lombardy), San Paolo hospital (Milano, Lombardy), San Raffaele hospital (Milano, Lombardy), Vizzolo Predabissi hospital (Milano, Lombardy), San Gerardo dei Tintori hospital (Monza, Lombardy), San Matteo hospital (Pavia, Lombardy), Galmarini-Tradate hospital (Varese, Lombardy), Salesi Ancona hospital (Ancona, Marche), Carlo Urbani hospital (Jesi, Marche), Principe di Piemonte hospital (Senigallia, Marche), Madonna del Soccorso hospital (San Benedetto del Tronto, Marche), Mazzoni hospital (Ascoli Piceno, Marche), Augusto Murri hospital (Fermo, Marche), Civitanova Marche hospital (Civitanova Marche, Marche), Macerata hospital (Macerata, Marche), San Salvatore hospital (Pesaro, Marche), Santa Croce hospital (Fano, Marche), Santa Maria della Misericordia hospital (Urbino, Marche), Antonio Cardarelli hospital (Campobasso, Molise), San Timoteo hospital (Campobasso, Molise), Ferdinando Veneziale hospital (Isernia, Molise), Cesare Arrigo hospital (Alessandria, Piedmont), Maggiore hospital (Novara, Piedmont), Giuseppe Brotzu hospital (Cagliari, Sardinia), San Francesco hospital (Nuoro, Sardinia), San Martino hospital (Oristano, Sardinia), Santissima Annunziata hospital (Sassari, Sardinia), Giovanni di Cristina hospital (Palermo, Sicily), Meyer hospital (Firenze, Tuscany), Mugello hospital (Firenze, Tuscany), San Giuseppe hospital (Firenze, Tuscany), Santa Maria Annunziata hospital (Firenze, Tuscany), Cecina hospital (Livorno, Tuscany), San Luca hospital (Lucca, Tuscany), Versilia hospital (Lucca, Tuscany), Apuane hospital (Massa-Carrara, Tuscany), Santa Chiara hospital (Pisa, Tuscany), San Jacopo Hospital (Pistoia, Tuscany), Bolzano Central hospital (Bolzano, Trentino-Alto Adige), Bressanone hospital (Bolzano, Trentino-Alto Adige), Rovereto hospital (Trento, Trentino-Alto Adige), Citt\u0026agrave; di Castello hospital (Perugia, Umbria), Gubbio e Gualdo Tadino hospital (Perugia, Umbria), San Giovanni Battista (Perugia, Umbria), Santa Maria della Misericordia hospital (Perugia, Umbria), Santa Maria della Stella hospital (Terni, Umbria), Santa Maria hospital (Terni, Umbria), all the hospitals of Veneto. These hospitals collected data on RSV bronchiolitis-related hospitalizations in pediatric, neonatology, or pediatric intensive care units from November 2023 to March 2024, and again from November 2024 to March 2025, through the hospital coding system used for RSV bronchiolitis case classification.\u003c/p\u003e\u003cp\u003eFor each region, we reported the start date of prophylaxis campaign during the epidemic season 2024\u0026ndash;2025, children eligible for immunization (born during the epidemical season from October 2024b to March 2025 or ot-of-season born), major issues encountered during this first campaign.\u003c/p\u003e\u003cp\u003eAfterwards we collected for each region the following data:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003enumber of hospital admissions for RSV bronchiolitis, month by month from October 2023 to March 2024 and from October 2024 to March 2025, through the sum of admissions in the sentinel hospitals of the region;\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003ecumulative number of admissions for RSV bronchiolitis in intensive care units from October 2023 to March 2024 and from October 2024 to March 2025, through the sum of PICU admissions in the sentinel hospitals of the region;\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003epercentage reduction in hospital admission for RSV bronchiolitis in epidemic season 2024-\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003e2025 compared to previous epidemic season 2023\u0026ndash;2024.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eWe have collected the vaccination and immunization recommendations from 19 Italian regions and analyzed differences and outcomes. The rollout of nirsevimab prophylaxis against RSV in Italy has been marked by wide heterogeneity among regions, with differences in start dates, organizational barriers, and drug availability. Some regions were able to launch their campaigns early and without significant obstacles, while others faced delays, shortages, and bureaucratic challenges that slowed implementation (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eHeterogeneity of nirsevimab prophylaxis among Italian regions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRegion\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCampaign Start Date\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eIssues\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAbruzzo\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e07-Jan-25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDelayed activation, tender process.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eApulia\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eShort periods of drug unavailability.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBasilicata\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e06-Dec-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNot specified.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCalabria\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16-Dec-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDifficult coverage of previously born infants, low-dose availability.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCampania\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBureaucratic difficulties in entering newborns into the platform.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEmilia-Romagna\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28-Oct-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNone.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eFriuli-Venezia Giulia\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e04-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInitial difficulties in obtaining doses, then regular start.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLazio\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11-Dec-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLate start and limited dose availability.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLiguria\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e05-Dec-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDrug availability/number of doses.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLombardy\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e01-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNone.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMarche\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e01-Dec-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDelayed drug availability.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eMolise\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDrug unavailable from the second half of December 2024.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePiedmont\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e01-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNone.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSardinia\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e16-Dec-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eLack of availability of 100 mg vials.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSicily\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNot specified.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTuscany\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e04-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNone.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTrentino-Alto Adige\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28-Oct-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNone.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eUmbria\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20-Jan-25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRegional Council resolution at the end of November 2024. Delay in doses.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eVeneto\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e04-Nov-24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNone.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eIn Northern and Central Italy, several regions demonstrated strong preparedness. Emilia Romagna and Trentino Alto Adige were among the first to start at the end of October 2024, followed closely by Lombardy, Piedmont, Tuscany, and Veneto in early November. These regions largely reported no major issues, indicating effective planning and coordination. Friuli Venezia Giulia also began in early November, experiencing only brief difficulties in obtaining doses before establishing regular supply.\u003c/p\u003e\u003cp\u003eBy contrast, other regions encountered interruptions or barriers that slowed the campaign. Apulia, starting in mid-November, faced short periods of unavailability. Marche launched at the beginning of December but was affected by the delayed delivery of doses. Liguria and Lazio, both beginning in December, struggled with limited availability, while Campania dealt with bureaucratic obstacles in enrolling newborns into the digital platform. Calabria and Sardinia, also starting in December, reported more severe problems, including difficulties in covering infants born before the campaign began, insufficient doses, and lack of 100 mg vials. Molise, despite starting in late November, experienced a complete absence of supply from January onward.\u003c/p\u003e\u003cp\u003eOther regions began later still. Basilicata activated prophylaxis in December but did not provide specific details on difficulties. Abruzzo delayed its start until early January 2025 due to tender procedures, and Umbria only launched in late January, slowed by a late Regional Council resolution and limited drug availability.\u003c/p\u003e\n\u003ch3\u003eReport on RSV Admissions in Italian Hospitals (2023–2024 vs. 2024–2025 seasons)\u003c/h3\u003e\n\u003cp\u003eHospital admissions of neonates and infants with RSV infections during the last two seasons show a marked overall decline across Italian regions, although the extent of reduction varied significantly from North to South. The data indicate both widespread decreases in case burden and striking regional differences in the magnitude of reduction (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eREGION\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNeonatology \u0026amp; pediatrics\u003c/p\u003e\u003cp\u003eadmissions\u003c/p\u003e\u003cp\u003e2023\u0026ndash;2024\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNeonatology \u0026amp; pediatrics\u003c/p\u003e\u003cp\u003eadmissions\u003c/p\u003e\u003cp\u003e2024\u0026ndash;2025\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAbruzzo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-40.5%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eApulia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e118\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-50.8%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBasilicata\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-36.1%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCalabria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-71.8%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCampania\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e555\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e336\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-39.4%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEmilia-Romagna\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e519\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e305\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-41.2%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFriuli-Venezia Giulia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-83.7%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLazio\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e438\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e294\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-32.9%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLiguria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e227\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e120\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-47.1%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLombardia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e832\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-63.9%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMarche\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e210\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e179\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-14.8%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMolise\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-22.9%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePiemonte\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e148\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e53\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-64.2%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSardinia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e158\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-52.3%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSicilia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1529\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e822\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-46.2%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eToscana\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e483\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e118\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026minus;\u0026thinsp;75.6%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTrentino-Alto Adige\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e154\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-40.9%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e179\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e146\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-18.4%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVeneto\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1203\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e379\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e-68.5%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eSeveral regions recorded very steep declines. Friuli-Venezia Giulia experienced the most dramatic drop, from 98 admissions in 2023\u0026ndash;2024 to only 16 in 2024\u0026ndash;2025, corresponding to nearly 84% fewer cases. Lombardy, one of the most populous regions, saw a substantial reduction of nearly two-thirds, moving from over 800 cases to 300. Piedmont, Tuscany and Veneto also showed pronounced declines, with reductions above 64%, 76% and 68% respectively.\u003c/p\u003e\u003cp\u003eRegions in the South also reflected meaningful decreases, though with different intensities. Sicily, which had by far the highest burden in the previous season with more than 1,500 admissions, reported a 46% decline but still accounted for over 800 cases in 2024\u0026ndash;2025, remaining the region with the heaviest caseload. Campania and Apulia also showed decreases of around 40\u0026ndash;50%, while Calabria achieved a more dramatic reduction of almost 72%, moving from 32 cases down to only 9. But, this is the result of analysis a single hospital from the region. Sardinia\u0026rsquo;s admissions dropped by over half, confirming a significant downward shift.\u003c/p\u003e\u003cp\u003eIn Central Italy, Lazio recorded nearly a 33% decrease, falling from 438 admissions to 294. Marche saw only a modest reduction of about 15%, with 179 cases still reported. Umbria and Molise also showed more contained decreases, of 18% and 23% respectively, suggesting that RSV activity remained relatively stable compared to the stronger declines observed elsewhere.\u003c/p\u003e\u003cp\u003eRegions of the North generally saw consistent reductions. Emilia Romagna, with over 500 cases in 2023\u0026ndash;2024, reported a 41% decline to 305 admissions. Liguria recorded a nearly 47% decrease. Trentino Alto Adige showed a 41% reduction, while Basilicata, despite lower absolute numbers, saw a significant decline of 36%.\u003c/p\u003e\n\u003ch3\u003eReport on PICU Admissions for RSV in Italian Regions (2023–2024 vs. 2024–2025 seasons)\u003c/h3\u003e\n\u003cp\u003eThe number of admissions to Pediatric Intensive Care Units (PICU) for RSV infection decreased substantially across most Italian regions between the 2023\u0026ndash;2024 and 2024\u0026ndash;2025 seasons, though with notable variability in magnitude and distribution (Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eREGION\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePICU admissions\u003c/p\u003e\u003cp\u003e2023\u0026ndash;2024\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTI 2024\u0026ndash;2025\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eChanges PICU admissions\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAbruzzo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eApulia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBasilicata\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e73%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCalabria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e100%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCampania\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e44%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEmilia-Romagna\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e54%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFriuli-Venezia Giulia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e90%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLazio\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e72%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLiguria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNd\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLombardy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e127\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e70%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMarche\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e80%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMolise\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePiedmont\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e46%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSardinia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e78%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSicily\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e73%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTuscany\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e82%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTrentino-Alto Adige\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e79%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eUmbria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e52%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVeneto\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e116\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e77%\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eRegions with the highest case burden in the previous season showed marked reductions. Lombardy dropped from 127 admissions to 38, representing a 70% decrease, while Sicily, with 93 admissions previously, recorded a 73% reduction to 25. Friuli Venezia Giulia showed one of the most dramatic improvements, falling from 61 to just 6 cases, equivalent to a 90% decrease. Emilia Romagna also demonstrated strong progress, cutting admissions by more than half, from 41 to 19. Campania mirrored this trend, moving from 41 to 23 admissions, a 44% reduction.\u003c/p\u003e\u003cp\u003eOther regions with moderate burdens in 2023\u0026ndash;2024 also reported clear declines. Tuscany reduced admissions by 82%, from 66 to 12. Veneto fell from 116 to 27, an 77% reduction. Trentino Alto Adige dropped by 79%, from 14 to 3 Umbria, which had reported 25 admissions in the previous season, nearly halved the number to 12. Piemonte reduced admissions from 13 to 7, a 46% decline. Sardinia reported a 78% reduction, from 9 admissions down to 2.\u003c/p\u003e\u003cp\u003eSmaller regions with limited admissions showed mixed patterns. Basilicata fell sharply from 11 to 3 cases, a 73% reduction. Marche recorded a fall from 10 to 2, equivalent to an 80% decrease. Calabria registered no cases in the 2024\u0026ndash;2025 season compared to 3 previously, reflecting a complete elimination of PICU admissions. Abruzzo was an exception, with 4 admissions in both seasons, showing no change. Molise continued to report no admissions in either season. Data were not available for Liguria and Apulia, preventing direct comparison.\u003c/p\u003e\n\u003ch3\u003eRegional implementation of nirsevimab prophylaxis in Italian regions\u003c/h3\u003e\n\u003cp\u003eIn Italy, the regional implementation of nirsevimab prophylaxis against RSV bronchiolitis showed clear variability in both timing and effectiveness, which can be grouped into three main performance clusters. We have classified the regions on the basis of their policies and of the disease outcome (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). High-performing regions (group 1) included Calabria, Friuli-Venezia Giulia, Lombardy, Piedmont, Tuscany and Veneto which achieved the strongest outcomes, with more than a 60% reduction in hospital admissions for bronchiolitis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). These successes were largely due to an early start of prophylaxis, often in October 2024, combined with excellent coordination between neonatology units, pediatric services, and pharmacies. In these regions, coverage was broad, including infants born outside the main epidemic window, and no major drug supply constraints were reported. The result was not only a sharp reduction in hospitalizations but also a significant drop in pediatric intensive care unit (PICU) admissions. These regions represent a benchmark model for early activation, good planning, and seamless organizational integration.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCriteria\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRegions\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eSummary\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGroup 1\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDecrease in hospital admission for RSV bronchiolitis\u0026thinsp;\u0026gt;\u0026thinsp;60%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCalabria, Friuli-Venezia Giulia, Lombardy, Piedmont, Tuscany, Veneto\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eHigh-performing regions with, in most cases, early and smooth implementation, no reported major issues, strongly reduction in PICU admissions\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGroup 2\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDecrease in hospital admission for RSV bronchiolitis from 30% to 59%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eAbruzzo, Apulia, Basilicata, Campania, Emilia-Romagna, Lazio, Liguria, Sardegna, Sicily, Trentino-Alto Adige\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDecent impact on admissions, though not as consistent, prophylaxis started in November/January or limited immunization of out-of-season born, mild to moderate issues\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGroup 3\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDecrease in hospital admission for RSV bronchiolitis\u0026thinsp;\u0026lt;\u0026thinsp;25%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eUmbria, Molise, Marche\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDelayed activation and/or drug shortages likely limited the effectiveness of the intervention\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eModerately effective regions (group 2), included Abruzzo, Apulia, Basilicata, Campania, Emilia-Romagna, Lazio, Liguria, Sardegna, Sicily, and Trentino-Alto Adige, saw reductions of 30\u0026ndash;59% in RSV-related hospitalizations (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). While the intervention was still effective, its impact was less consistent compared to Group 1. In several cases, prophylaxis started late (November or even December 2024), while in others coverage was more limited, particularly for infants born out of the epidemic peak season. Organizational barriers also played a role, including fragmented integration between hospitals and community healthcare, variable communication efforts towards families, and temporary but impactful drug supply shortages. The overall impact was still positive, but these regions would benefit from better planning and stronger logistical coordination to match the outcomes of the top-performing group. While other Regions showed delayed or ineffective implementation including (Group 3) Umbria, Molise, and Marche that experienced the least impact, with little or no improvement in hospitalization rates (reductions below 25%). Here, prophylaxis was generally launched only in December 2024 or January 2025, which coincided with or followed the peak of RSV infections, leaving many newborns unprotected (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Additional challenges included procurement delays and limited coordination across local health authorities. As a result, both hospital admissions and PICU admissions remained largely unchanged.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe implementation of nirsevimab across Italy revealed marked regional heterogeneity, mirroring patterns described in recent international studies. Northern and Central areas, such as Emilia Romagna, Lombardy, Piedmont, Tuscany, Veneto, and Trentino Alto Adige, launched campaigns earlier and with fewer logistical barriers, while Southern regions, including Calabria, Campania, Sardinia, and Molise, faced delays and organizational obstacles, often compounded by limited drug supply. These difficulties echo findings from Spain and France, where consistent drug availability and efficient planning were critical to achieving strong protective effects [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In Catalonia and Andorra, systematic early immunization led to clear reductions in RSV hospitalizations, while in Paris, case-control analyses confirmed protection against bronchiolitis admissions. Additional evidence from French PICUs demonstrated an estimated 75.9% effectiveness in preventing severe RSV cases [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], and Andalusian data confirmed that timely prophylaxis reduced both hospitalizations and intensive care admissions [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Findings from Luxembourg similarly showed that population-wide prophylaxis substantially lowered RSV hospitalizations during the 2023/24 season [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Together, these data highlight how early readiness, reliable supply, and coordinated execution consistently translate into measurable population benefits \u0026mdash; an experience echoed in Italy, where regions with earlier activation were better able to avoid shortages and maintain smoother rollouts.\u003c/p\u003e\u003cp\u003eIn parallel, data on RSV-related hospitalizations in Italy showed a nationwide downward trend, with the sharpest declines in Friuli Venezia Giulia, and more modest decreases in Marche, Molise, and Umbria. Some regions, such as Sicily, Campania, and Lombardy, continued to carry a high absolute burden, likely reflecting demographic factors and differences in preventive implementation. Nevertheless, reductions in pediatric intensive care unit (PICU) admissions were consistent across most regions, with the largest relative decreases observed in Friuli Venezia Giulia, Tuscany, Calabria and Marche. Larger regions such as Lombardy, Emilia Romagna, and Sicily still sustained the highest absolute numbers, but all demonstrated marked improvements compared to the prior season, suggesting a meaningful nationwide decline in severe RSV cases.\u003c/p\u003e\u003cp\u003eA combined analysis of prophylaxis rollout, pediatric hospital admissions, and PICU data stratified Italian regions into three performance groups. \u003cb\u003eGroup 1\u003c/b\u003e ( Calabria, Friuli-Venezia Giulia, Lombardy, Piedmont, Tuscany and Veneto) represented high-performing areas, marked by early campaign activation, absence of major logistical barriers, and reductions in hospital burden often exceeding 60%. \u003cb\u003eGroup 2\u003c/b\u003e ( Abruzzo, Apulia, Basilicata, Campania, Emilia-Romagna, Lazio, Liguria, Sardinia, Sicily, trentino-Alto Adige) began later and faced operational hurdles such as intermittent shortages or bureaucratic delays, yet still achieved30\u0026ndash;60% reductions, albeit less consistently. \u003cb\u003eGroup 3\u003c/b\u003e ( Marche, Molise, Umbria) experienced late activation and limited impact, with reductions generally below 25%.\u003c/p\u003e\u003cp\u003eTaken together, these findings underscore the importance of early planning, reliable supply chains, and organizational efficiency in maximizing the impact of nirsevimab prophylaxis. Regions that were able to start early and operate smoothly achieved the most substantial reductions in both pediatric and intensive care admissions. Conversely, delayed or troubled rollouts yielded only modest benefits, reinforcing the time-sensitive nature of RSV prevention.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThis study was conducted through the analysis of hospital discharge forms (SDOs) for bronchiolitis and therefore, did not require access to individual patient data. The study is exclusively based on administrative datasets.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthical approval and Consent to Participate\u003c/strong\u003e\u003cp\u003edeclarations: not applicable.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e\u003cp\u003eNot applicable\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding.\u003c/h2\u003e\u003cp\u003eThis study has been funded by the Societ\u0026agrave; Italiana di Pediatria (SIP).\u003c/p\u003e\u003ch2\u003eAuthors' contributions.\u003c/h2\u003e\u003cp\u003eRB has designed the study and written the article, RA has designed the study, all the other Authors have collected and processed the data provided by hospitals and regional health authorities for this study. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements.\u003c/h2\u003e\u003cp\u003eWe would like to thank all the regional and hospital authorities who have supported the data collection.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials.\u003c/h2\u003e\u003cp\u003eThe datasets during and/or analysed during the current study are available from the corresponding author on reasonable request\u003c/p\u003e\u003cp\u003eCompeting interests. The authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAzzari C, Baraldi E, Bonanni P, Bozzola E, Coscia A, Lanari M et al. Epidemiology and prevention of respiratory syncytial virus infections in children in Italy. Ital J Pediatr [Internet]. 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Eurosurveillance. 2024;29. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2807/1560-7917.ES.2024.29.4.2400033\u003c/span\u003e\u003cspan address=\"10.2807/1560-7917.ES.2024.29.4.2400033\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"italian-journal-of-pediatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"itjp","sideBox":"Learn more about [Italian Journal of Pediatrics](http://ijponline.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ITJP/default.aspx","title":"Italian Journal of Pediatrics","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7938646/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7938646/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRespiratory syncytial virus (RSV) remains a leading cause of bronchiolitis and hospitalization in infants across Italy, particularly during predictable seasonal outbreaks. With the 2023\u0026ndash;2025 RSV seasons marking the first large-scale rollout of the monoclonal antibody nirsevimab, this nationwide observational study evaluated implementation strategies and outcomes across 19 Italian regions. Data were collected through the Italian Society of Pediatrics and the Italian Society of Neonatology, focusing on differences in rollout timing, logistics, and RSV-related hospital and pediatric intensive care unit (PICU) admissions.\u003c/p\u003e\u003cp\u003eThe results highlighted significant regional heterogeneity. Northern and central regions such as Veneto, Lombardy, and Tuscany initiated prophylaxis earlier and experienced fewer logistical barriers, resulting in marked reductions in RSV hospitalizations - up to 83.7% in Friuli-Venezia Giulia. Conversely, southern and smaller central regions, including Molise, Marche, and Umbria, faced delayed starts, supply shortages, and bureaucratic challenges, leading to more modest decreases. PICU admissions mirrored these trends.\u003c/p\u003e\u003cp\u003eOverall, the national introduction of nirsevimab correlated with a significant reduction in RSV-related morbidity, especially in regions with early, well-organized rollouts. Comparative international studies from France, Spain, and Luxembourg reinforce the Italian findings: timely and universal prophylaxis leads to substantial public health benefits. The study concludes that early campaign activation, consistent drug availability, and efficient organization are critical for maximizing the protective effect of RSV immunization.\u003c/p\u003e","manuscriptTitle":"Impact of Regional heterogeneity of RSV infection prophylaxis on bronchiolitis in Italy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-19 11:50:04","doi":"10.21203/rs.3.rs-7938646/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-11-10T04:54:12+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-07T10:41:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-04T03:09:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"Italian Journal of Pediatrics","date":"2025-11-03T05:15:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"italian-journal-of-pediatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"itjp","sideBox":"Learn more about [Italian Journal of Pediatrics](http://ijponline.biomedcentral.com)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ITJP/default.aspx","title":"Italian Journal of Pediatrics","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f8fd5804-139c-4c9a-910a-326af271e37e","owner":[],"postedDate":"November 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-02-05T06:26:29+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-19 11:50:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7938646","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7938646","identity":"rs-7938646","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}