Serum Vitamin D Level in Children With Bronchiolitis

Serum Vitamin D Level in Children With Bronchiolitis | 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 Article Serum Vitamin D Level in Children With Bronchiolitis Thet Su Su Aung, Myat Myat Khine This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9118634/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Acute bronchiolitis is the most common lower respiratory tract infection during the first year of life. Vitamin D is an important contributing factor to the increasing incidence and severity of bronchiolitis over the past three decades. Numerous international studies have suggested that low vitamin D levels are associated with the severity of bronchiolitis. Purpose This study aimed to determine serum vitamin D levels in infants hospitalized with acute bronchiolitis in Myanmar. Method A cross-sectional analytical study was conducted in medical units of Yankin Children’s Hospital from August 2022 to July 2023. A total of seventy-five children aged one to twelve months old were included and the Wang clinical severity score was assessed for severity categorization. In this study, majority of children with severe bronchiolitis were found to be vitamin D deficient. Results A total of 75 children, 86% of the study population, were in the one-to-six-month- old age group and only ten children, 13.3 percent, were in the six-month to one -year-old age group. According to the Wang clinical severity score, severe bronchiolitis was found in 64% of the study population, and non-severe bronchiolitis was detected in 36%. In this study, the mean vitamin D level in the studied population was 38.54 ± 17.67 nmol/L in non-severe bronchiolitis patients and 35.31 ± 15.83 nmol/ L in severe bronchiolitis patients. In the present study, 94.1% of severe bronchiolitis cases were vitamin D deficient, and only 5.9% of none severe bronchiolitis cases were vitamin D deficient. A total of 59.3% of severe bronchiolitis cases were vitamin D insufficient, and 40.7% of non-severe bronchiolitis cases were vitamin D insufficient. Conclusion All of the vitamin D sufficient patients had non- severe bronchiolitis. Therefore, there was a statistically significant association between vitamin D levels and the severity of bronchiolitis. Health sciences/Diseases Health sciences/Health care Biological sciences/Immunology Health sciences/Medical research Bronchiolitis Vitamin D Infant Child Introduction Acute bronchiolitis is the most common acute respiratory tract infection during infancy and is a significant cause of hospitalization during the first year of life [1]. Although it may occur during any season, it most commonly occurs during the winter. Despite its self-limiting nature in most cases, several risk factors are associated with an increased likelihood of more severe disease. Children with bronchiolitis with underlying cardiopulmonary disorders, musculoskeletal disorders, premature birth, bronchopulmonary dysplasia, exposure to cigarette smoke and air pollution have an increased risk of severe disease [2]. Acute bronchiolitis is a significant cause of respiratory disease. In total, 150 million new cases are reported worldwide every year, and 11–20 million (7–13%) of these cases are severe enough to require hospital admission [3]. Approximately 95% of all cases occur in developing countries [4]. Vitamin D plays a key role in activating the innate immune system particularly during infections of lower respiratory tract, including bronchiolitis. Vitamin D increases mucociliary clearance, regulates epithelial cell production and modulates inflammatory pathways [5]. Inadequate serum vitamin D concentrations have also been associated with acute respiratory infections. Infants seem to be susceptible to viral rather than bacterial infections in the face of vitamin D deficiency. The incidence of viral infections, particularly in bronchiolitis, typically peaks in the winter months when cutaneous vitamin D synthesis is naturally impaired. Some studies have reported that adequate vitamin D concentrations play a potential role in protecting against upper and lower respiratory tract infections [6] Recently, the harmful effects of pathogens that cause bronchiolitis have strengthened, because of increasing rates of vitamin D deficiency in infants. Vitamin D has been demonstrated to play roles in both immune system activation and the prevention of infections by microorganisms. Vitamin D deficiency affects susceptibility to infections and triggers wheezing at an early age and the response to this process [7]. Bronchiolitis is among the one of the common causes of hospital admission in Myanmar. Vitamin D deficiency in children with bronchiolitis may worsen the severity of bronchiolitis. This study aimed to determine the serum vitamin D levels and an association between the vitamin D levels and the severity of bronchiolitis may exist. Materials and methods Study design Cross-sectional descriptive study Study period This study was carried out one year after the approval of Academic Board of Postgraduate Studies (Pediatric) of the University of Medicine 2, Yangon. Study area Medical units of Yankin Children Hospital Study population All children under one year of age with bronchiolitis were admitted to medical units of Yankin Children Hospital All children up to one year old with bronchiolitis who fulfilled the inclusion criteria were collected consecutively in all medical wards. After informed written consent was obtained from parents or caregivers, relevant information was collected in pro forma. Moreover, a severity assessment was performed by a researcher to avoid inter-observer variation by using the Wang scoring system. After that, two ml of blood was collected in a plain tube and the sample was sent to YKCH laboratory during 24hours. Serum was obtained after centrifugation at 1500 rpm for 10 minutes. The serum for Vitamin D measurement was stored at -80°C in the YKCH laboratory. The serum samples were transported in a portable cool box with gel refrigerant to the Common Laboratory, University of Medicine 2. Serum vitamin D level was determined by the ELIZA method (Stat Fax 2600 washer and Stat Fax 2100 reader) at the Common Laboratory, University of Medicine 2. Afterward, the collected sample was discarded according to hospital refusal disposal guidelines. Data were collected by using pro forma. To ensure completeness, consistency and correctness, the data collected were checked manually by the interviewers. After the data and code were checked, the data were entered into Microsoft excel 2010. For data validation, a check file was used ,and the data were edited if necessary. Data analysis was performed by using SPSS (Statistical Package for Social Science) 25. Graphs and charts were shown for clear presentation. For continuous data the mean, medium and standard deviation, etc., also were also used to calculate summary measures. Numerical data such as severity score was shown with the mean and standard deviation. Ethical Approval This study followed the research guidelines of the University of Medicine 2(UM 2), Yangon as described in the booklet - Manual for Research Protocol and Dissertation/Thesis Writing, 2019 by UM 2, Yangon. This research protocol was submitted to the Academic Board of Post-graduate Studies (Pediatrics) of the University of Medicine 2, Yangon. This research was carried out only after approval was obtained from the Academic Board of Post graduate Studies (Pediatrics) of University of Medicine 2, Yangon and the ethics review committee of UM (2). All eligible children who met the selection criteria for this study had the chance to participate in this study. Parents or care givers were thoroughly explained in detail about the research by the researcher with a detailed information sheet. Only after they fully understood the nature of the study, including its aim and objectives, methodology, procedures, duration, risks and benefits, and the consent from the parent, were they invited to participate in the study. They reported that minimal side effects such as pain occurred, and this study will benefit directly as well as to help the treatment of upcoming children with bronchiolitis. If they agreed, the written informed consent was obtained. Participation in this research was voluntary. They had the right to refuse to participate in the study and withdraw at any time from the study without any effect. All the standard treatments were continued regardless of the status of the participant in the research. Children with bronchiolitis were closely monitored throughout the research process by the researcher. No money or any forms of abnormal incentives or material goods was supplied to the participants by the researcher for taking part in this study. The investigator strictly maintained the rules of privacy and confidentiality. The history taking, examination and the research work were performed in places with proper privacy. No names were mentioned in this study. Only a coded system was used. The research information was kept in a password-protected file under the care of the investigator. The research data will be used, published and shared for the academic purposes only with no personal identifiers – such as in this dissertation/thesis paper, in medical seminars, conferences and medical publications. Results The most affected age group was 1-6 months (86.7%) among study population. However, 13.3% of the study population was between 6 months and 1year old. In terms of sex distribution, 70.7% of the study population was male and 29.3% was female. Although 36% of participants had nonsevere bronchiolitis, 64% of the study population had severe bronchiolitis according to the Wang clinical severity score. Approximately 95% of the patients studied had vitamin D insufficiency and deficiency. Seventy-two percent of the studied population was vitamin D insufficient. A total of 22.7% of the studied children were vitamin D deficient. Only 5.33% were vitamin D sufficient. The mean vitamin D concentrations in nonsevere bronchiolitis and severe bronchiolitis patients in the studied population were 44.29±19.55 nmol/L and 35.31±15.83 nmol/L, respectively. In this study, 94.1% of severe bronchiolitis cases were vitamin D deficient, and only 5.9% of non- severe bronchiolitis cases were vitamin D deficient. A total of 59.3% of severe bronchiolitis were vitamin D insufficient, 40.7% of nonsevere bronchiolitis cases were vitamin D insufficient. All of the vitamin D sufficient patients had non- severe bronchiolitis. Therefore, there was a statistically significant correlation between vitamin D levels and the severity of bronchiolitis (p value <0.5). Table (1) Table (2) Table (3) Discussion This study aims to investigate as the sociation between serum vitamin D levels and the severity of bronchiolitis in children. This is the first study in Myanmar and a hospital-based cross sectional analytical study conducted at Yankin Children’s Hospital from August 2022 to July 2023 after receiving approval from the academic board of the University of Medicine (2). A total of seventy-five children meeting the inclusion criteria were included. The severity of the studied infants was categorized by the Wang severity score, and serum vitamin D levels were determined in the common laboratory of the University of Medicine (2). In this study, the majority of children with severe bronchiolitis were found to be vitamin D deficient. Background and clinical characteristics of children with bronchiolitis Age distribution of patients with bronchiolitis A total of 65 children, 86 % of the study population, were in the one-to-six-month-old age group, and only ten children, 13.3 %, were in the six- month- to one-year age group. In the present study, one- to-six-month-old age group was more strongly affected than the six-month to one -year age group was. The minimum age in this study was one month, and the maximum age was 12 months. These findings are consistent with the results of the study by Ye-Kyaw-Thu [8], which revealed that bronchiolitis was most frequent in children in the one- to- six- month age group. This finding is in line with the findings of other international studies. For instance, a study carried out by Golan-Tripto et al [9] in Isreal, a revealed that three to nine months were the most commonly affected age groups. A study carried out by Alakas et al [10], in Turkey also revealed that the age group commonly affected by bronchiolitis was under one year age group. The median age group was 9 months. Gender distribution of bronchiolitis In the present study, males were more affected (70.7%) than females were (29.3%) among the children with bronchiolitis. Slightly larger male populations were found in the Turkey and Isreal studies. In the study by Alakas et al [10], 57.1% of the study population was male and in the study by Golan-Tripto et al [9], 58% of the study population. In contrast, a study by Ye- Kyaw -Thu [8], females were more affected (57.8%). Clinical Characteristics of Children with Bronchiolitis In the present study, the clinical parameters were assessed by using the Wang clinical severity score. According to the Wang clinical severity score, severe bronchiolitis was found in 64% of the study population, and nonsevere bronchiolitis was found in 36% of the study population. In contrast to the present study, Rahmati et al [11] used a standard bronchiolitis severity score, which was used to classify as mild, moderate and severe bronchiolitis. In their study, 25.9%, 67.05% and 7.05% of the infants were mild, moderate, severe bronchiolitis, respectively. In the study by Alakas et al [10], infants were assessed by using Modified Tal scoring. In their study, 36.3% of the study population had severe bronchiolitis and 63.7% had mild to moderate bronchiolitis. Various respiratory scores have been used to evaluate the response to acute bronchiolitis in clinical practice and clinical trials. The Wang Respiratory score among the commonly used scores for the assessing the severity of acute bronchiolitis because the physical signs used in these respiratory scores are simple and well categorized. Vitamin D level In this study, the mean vitamin D concentration in the studied population was 38.54±17.67 nmol/L. Our results differed considerably from those of other international studies. In a study by Alakas et al [10], the mean vitamin D concentration in children with bronchiolitis was 50.19±15.32 nmol/L. In a study by Rahmati et al [11], the mean serum level of vitamin D concentration in children with bronchiolitis was 58.74±13.44 nmol/L. Similarly, Beigelman et al [12] reported that the average serum concentration of 25 OH-vitamin D was 75.54 nmol/L. Therefore, the mean vitamin D level in this study was significantly lower than that in other studies. Vitamin D level and severity of bronchiolitis In this study, the mean serum vitamin D concentration was 44.29±19.55 nmol/L in nonsevere bronchiolitis patients and 35.31±15.83 nmol/ L in severe bronchiolitis patients. The mean serum vitamin D concentration was greater in patients with non-severe bronchiolitis than in those with severe bronchiolitis. Low serum vitamin D level was significantly associated with severe bronchiolitis. These findings were consistent with those of Rahmati et al [11] study. In their study, 54.1% of their study population had insufficient vitamin D levels and 45.9% of their study population had normal vitamin D levels. The results of the study by Alakas et al [10] corroborated with those of the present study. Their study revealed that vitamin D deficiency or insufficiency was as high as 47.8% in infants with bronchiolitis. A significantly greater proportion of infants with low vitamin D levels had severe bronchiolitis. Infants admitted to the intensive care unit (40.1%) had significantly greater degrees of vitamin D deficiency or insufficiency. Therefore, Vitamin D deficiency is closely linked to severe bronchiolitis. In the study by Golan-Tripto et al [9] study, vitamin D levels were significantly lower in the bronchiolitis group than in the control group. Deficient vitamin D levels (< 50 nmol/L) were detected in 73 % of the patients in the bronchiolitis group. However, no correlation was found between serum vitamin D levels and bronchiolitis severity, which was assessed by the modified Tal Score and by the length of hospital stay. In a prospective study by Inamo et al [13], serum vitamin D levels were determined in 28 Japanese children hospitalized with lower respiratory tract infections. Infants whosw serum vitamin D concentration was < 10 ng/ml, required supplemental oxygen and ventilator support. Vitamin D deficiency is associated with acute respiratory tract infection because it might be related to its important role in the innate immune system. Vitamin D is involved in inducing the activity of the endogenic antimicrobial proteins, defensins and cathelicidin, which fight against bacterial and viral infections [14]. Cathelicidin is an AMP whose expression is up regulated by 1,25(OH)2D. and plays multiple roles in recent studies. The production of cathelicidin in primary cultures of normal bronchial epithelial cells was reported in recently studies. They were able to demonstrate that 1,25D(OH)2D stimulated the induction of cathelicidin in this cell type. These studies also provided evidence that 1,25D(OH)2D-treated bronchial epithelial cells exhibit increased antibacterial activity [15][16]. Garg et al [15] conducted a five-year case control study in India. In their study, vitamin D deficiency was found in 85.7% of the patients (admitted patients with bronchiolitis, pneumonia and asthma) and only 14.2% of the controls (ambulatory care). Similarly, vitamin D deficiency was higher in the case group (74.19%) than in the control group (25.8%). Therefore, they concluded that low vitamin D levels were significantly correlated with acute lower respiratory tract infections. In the study by Belderbos et al [17] , 54% of the neonate had insufficient vitamin D and 46% of the neonate had sufficient vitamin D. Cord blood vitamin D concentrations were strongly associated with maternal vitamin D3 supplementation during pregnancy. Compare with neonates born with normal vitamin D levels, neonates born with vitamin D insufficiency had a sixfold increased risk of RSV lower respiratory tract infection in the first year of life. In the Hnin Lei Aye [18] study, one- third of the acute respiratory tract infection children in the study had vitamin D insufficiency and deficiency. In the present study, 94.1% of severe bronchiolitis cases were vitamin D deficient, and only 5.9% of non- severe bronchiolitis cases were vitamin D deficient. A total of 59.3% of children with severe bronchiolitis were vitamin D insufficient, and 40.7% of those with nonsevere bronchiolitis were vitamin D insufficient. All of the vitamin D sufficient patients had nonsevere bronchiolitis. Therefore, there was statistically significant association between vitamin D level and severity of bronchiolitis. Conclusion and Recommendations Bronchiolitis is among the important causes of acute respiratory illness in children and causes significant morbidity and mortality in infancy. In this study, vitamin deficiency and insufficiency were found in infants with severe bronchiolitis. There is a significant association between vitamin D levels and the severity of bronchiolitis. Therefore, vitamin D supplementation for infants and pregnant mothers should be considered in our country. The American Academy of Pediatrics (AAP) has doubled the recommended intake of vitamin D to 400 IU per day for infants. In this study, all the study patients were admitted to hospital , and thus, further studies should be carried out on mild cases and ambulatory cases. Declarations Funding declaration This research was supported from an external grant from the Department of Medical Research (DMR) in Myanmar (DMR Ext Grant 2023/3024). Competing Interests Financial interests The authors have no relevant financial or nonfinancial interests to disclose. Author Contributions All the authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Dr Myat Myat Khine. The first draft of the manuscript was written by Dr Thet Su Su Aung and all the authors commented on previous versions of the manuscript. All the authors read and approved the final manuscript. Ethics approval This study was performed in accordance with the principles of the Declaration of Helsinki. Approval was granted by from the Academic Board of Postgraduate Studies (Pediatrics) of the University of Medicine 2, Yangon and the ethic review committee of UM (2), Yangon, Myanmar. Consent to participate Written informed consent was obtained from the parents. Data availability statement Data are available upon reasonable request to the corresponding author" References Stockman, Lauren J. MPH; Curns, Aaron T. MPH; Anderson, Larry J. MD; Fischer-Langley, Gayle MD, MPH. Respiratory Syncytial Virus-associated Hospitalizations Among Infants and Young Children in the United States, 1997–2006. The Pediatric Infectious Disease Journal 31(1):p 5–9, January 2012. | DOI: 10.1097/INF.0b013e31822e68e6 Silver AH, Nazif JM. Bronchiolitis. Pediatr Rev. 2019 Nov;40(11):568–576. doi: 10.1542/pir.2018-0260. PMID: 31676530. Tian J, Wang XY, Zhang LL, Liu MJ, Ai JH, Feng GS, Zeng YP, Wang R, Xie ZD. Clinical epidemiology and disease burden of bronchiolitis in hospitalized children in China: a national cross-sectional study. World J Pediatr. 2023 Sep;19(9):851–863. doi: 10.1007/s12519-023-00688-9. Epub 2023 Feb 16. PMID: 36795317; PMCID: PMC9933022. Rudan I, Boschi-Pinto C, Biloglav Z, Mulholland K, Campbell H. Epidemiology and etiology of childhood pneumonia. Bull World Health Organ. 2008 May;86(5):408 − 16. doi: 10.2471/blt.07.048769. PMID: 18545744; PMCID: PMC2647437. Akcan, F.A., Dündar, Y., Akcan, H.B., Uluat, A., Cebeci, D. and Ünlü, İ. (2019) Evaluation of nasal mucociliary clearance time in patients with vitamin-D deficiency. Eur Arch Otorhinolaryngol : 276(4); p.1075–80. https://doi.org/10.1007/s00405-019-05286-y Walker VP, Modlin RL. The vitamin D connection to pediatric infections and immune function. Pediatr Res. 2009 May;65(5 Pt 2):106R-113R. doi: 10.1203/PDR.0b013e31819dba91. PMID: 19190532; PMCID: PMC2925470. Meltem Erol, Hüseyin Kaya, Özlem Bostan Gayret, Özgül Yiğit, Şahin Hamilçıkan, Emrah Can (2017The Effect of Vitamin D Deficiency on the Severity of Bronchiolitis in Infants. J Pediatr Res:4-1-12(6) DO I: 10.4274/jpr.97658 Ye-Kyaw-Thu. (2019) Respiratory Synctial virus Genotypes and severity of Bronchiolitis Dr.Med.Sc Thesis, University of Medicine 2, Yangon. Golan-Tripto I, Loewenthal N, Tal A, Dizitzer Y, Baumfeld Y, Goldbart A. Vitamin D deficiency in children with acute bronchiolitis: a prospective cross-sectional case- control study. BMC Pediatr. 2021 Apr 30;21(1):211. doi: 10.1186/s12887-021-02666-4. PMID: 33931018; PMCID: PMC8085105. Alakaş Y, Celiloğlu C, Tolunay O, Matyar S. The Relationship between Bronchiolitis Severity and Vitamin D Status. J Trop Pediatr. 2021 Aug 27;67(4):fmab081. doi: 10.1093/tropej/fmab081. PMID: 34580716. RahmatiD, Mehran AhmadiD, Seyed Alireza SobhaniD, Morteza BakhshiID, HoseinHamadiyanID, Bahareh Alipour (2020), The Relationship Between Serum Vitamin D Level and Severity of Bronchiolitis in Infants Being Referred to in Bandar Abbas Children’s Hospital, Iran, Int Electron JMed 2020; 9(3):96–100. DOI:10.34172/iejm.2020.17 Beigelman A, Castro M, Schweiger TL, Wilson BS, Zheng J, Yin-DeClue H, Sajol G, Giri T, Sierra OL, Isaacson-Schmid M, Sumino K, Schechtman KB, Bacharier LB. Vitamin D Levels Are Unrelated to the Severity of Respiratory Syncytial Virus Bronchiolitis Among Hospitalized Infants. J Pediatric Infect Dis Soc. 2015 Sep;4(3):182-8. doi: 10.1093/jpids/piu042. Epub 2014 Jun 5. PMID: 26336601; PMCID: PMC4554201. Inamo Y, Hasegawa M, Saito K, Hayashi R, Ishikawa T, Yoshino Y, Hashimoto K, Fuchigami T. Serum vitamin D concentrations and associated severity of acute lower respiratory tract infections in Japanese hospitalized children. Pediatr Int. 2011 Apr;53(2):199–201. doi: 10.1111/j.1442-200x.2010.03224.x. PMID: 21648117. Leikina E, Delanoe-Ayari H, Melikov K, Cho MS, Chen A, Waring AJ, Wang W, Xie Y, Loo JA, Lehrer RI, Chernomordik LV. Carbohydrate-binding molecules inhibit viral fusion and entry by crosslinking membrane glycoproteins. Nat Immunol. 2005 Oct;6(10):995–1001. doi: 10.1038/ni1248. Epub 2005 Sep 11. PMID: 16155572. Garg D, Sharma VK, Karnawat BS. Association of serum vitamin D with acute lower respiratory infection in Indian children under 5 years: a case control study. Int JContemp Pediatrics. 2016;3(4):1164-9 DOI: http://dx.doi.org/10.18203/2349-3291.ijcp20163141 Yim S, Dhawan P, Ragunath C, Christakos S, Diamond G. Induction of cathelicidin in normal and CF bronchial epithelial cells by 1,25-dihydroxyvitamin D(3). J Cyst Fibros. 2007 Nov 30;6(6):403 − 10. doi: 10.1016/j.jcf.2007.03.003. Epub 2007 Apr 27. PMID: 17467345; PMCID: PMC2099696. Belderbos ME, Houben ML, Wilbrink B, Lentjes E, Bloemen EM, Kimpen JL, Rovers M, Bont L. Cord blood vitamin D deficiency is associated with respiratory syncytial virus bronchiolitis. Pediatrics. 2011 Jun;127(6):e1513-20. doi: 10.1542/peds.2010-3054. Epub 2011 May 9. PMID: 21555499. Hnin-Lei-Aye. (2014) Vitamin D level in Children with Pneumonia M.Med.Sc Thesis, University of Medicine 2, Yangon Tables Table 1. Characteristics of participants Characteristic of participants (n=75) Characteristic of participants n(%) Age of presentation 1 month – 6 months 65(86.7) >6 months– 1 year 10(13.3) Gender Male 53(70.7) Female 22(29.3) Severity of bronchiolitis Severe bronchiolitis 48(64) Non- Severe bronchiolitis Serum vitamin level Deficient Insufficient Sufficient 27(36) 17(22.7) 54(72) 4(5.3) Table 2. Serum vitamin D level and severity of bronchiolitis Severity of Bronchiolitis Serum vitamin D level Mean ± SD Range 95%CI Non severe(n=27) 44.29±19.55 10-100 36.9 to 51.7 t= - 2.165 p value=0.03 Severe(n=48) 35.31±15.83 7.5-65 30.34, 39.68 Total 38.54±17.67 7.5-100 34.5 to 42.5 Table 3. Association between vitamin D level and severity of bronchiolitis Serum vitamin D level(nmol/L) Number of children with bronchiolitis Total Non severe bronchiolitis Severe bronchiolitis Number Percentage Number Percentage Number Percentage Deficient (75) 4 100% 0 0 4 100% Total 27 36% 48 64% 75 100% Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 13 Apr, 2026 Reviews received at journal 11 Apr, 2026 Reviews received at journal 10 Apr, 2026 Reviewers agreed at journal 09 Apr, 2026 Reviewers agreed at journal 09 Apr, 2026 Reviewers invited by journal 28 Mar, 2026 Editor assigned by journal 28 Mar, 2026 Editor invited by journal 25 Mar, 2026 Submission checks completed at journal 24 Mar, 2026 First submitted to journal 24 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9118634","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":614157513,"identity":"0f3af8f8-32c3-481c-990f-bca2013507a5","order_by":0,"name":"Thet Su Su Aung","email":"data:image/png;base64,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","orcid":"","institution":"Manipal University College Malaysia","correspondingAuthor":true,"prefix":"","firstName":"Thet","middleName":"Su Su","lastName":"Aung","suffix":""},{"id":614157514,"identity":"11f28d94-88f7-4752-9231-49a0769dde16","order_by":1,"name":"Myat Myat Khine","email":"","orcid":"","institution":"University of Medicine 2 Yangon","correspondingAuthor":false,"prefix":"","firstName":"Myat","middleName":"Myat","lastName":"Khine","suffix":""}],"badges":[],"createdAt":"2026-03-14 00:23:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9118634/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9118634/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106402650,"identity":"419ca35c-ddd3-47e2-9329-23c817fc41ab","added_by":"auto","created_at":"2026-04-08 09:12:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":667364,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9118634/v1/71bb9ce0-a393-4862-a523-ce6d8d1dd570.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eSerum Vitamin D Level in Children With Bronchiolitis\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAcute bronchiolitis is the most common acute respiratory tract infection during infancy and is a significant cause of hospitalization during the first year of life [1]. Although it may occur during any season, it most commonly occurs during the winter. Despite its self-limiting nature in most cases, several risk factors are associated with an increased likelihood of more severe disease. Children with bronchiolitis with underlying cardiopulmonary disorders, musculoskeletal disorders, premature birth, bronchopulmonary dysplasia, exposure to cigarette smoke and air pollution have an increased risk of severe disease [2]. Acute bronchiolitis is a significant cause of respiratory disease. In total, 150\u0026nbsp;million new cases are reported worldwide every year, and 11\u0026ndash;20\u0026nbsp;million (7\u0026ndash;13%) of these cases are severe enough to require hospital admission [3]. Approximately 95% of all cases occur in developing countries [4].\u003c/p\u003e \u003cp\u003eVitamin D plays a key role in activating the innate immune system particularly during infections of lower respiratory tract, including bronchiolitis. Vitamin D increases mucociliary clearance, regulates epithelial cell production and modulates inflammatory pathways [5]. Inadequate serum vitamin D concentrations have also been associated with acute respiratory infections. Infants seem to be susceptible to viral rather than bacterial infections in the face of vitamin D deficiency. The incidence of viral infections, particularly in bronchiolitis, typically peaks in the winter months when cutaneous vitamin D synthesis is naturally impaired. Some studies have reported that adequate vitamin D concentrations play a potential role in protecting against upper and lower respiratory tract infections [6]\u003c/p\u003e \u003cp\u003eRecently, the harmful effects of pathogens that cause bronchiolitis have strengthened, because of increasing rates of vitamin D deficiency in infants. Vitamin D has been demonstrated to play roles in both immune system activation and the prevention of infections by microorganisms. Vitamin D deficiency affects susceptibility to infections and triggers wheezing at an early age and the response to this process [7].\u003c/p\u003e \u003cp\u003eBronchiolitis is among the one of the common causes of hospital admission in Myanmar. Vitamin D deficiency in children with bronchiolitis may worsen the severity of bronchiolitis. This study aimed to determine the serum vitamin D levels and an association between the vitamin D levels and the severity of bronchiolitis may exist.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e\u003cstrong\u003eStudy design\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCross-sectional descriptive study\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy period\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was carried out one year after the \u0026nbsp;approval of Academic Board of Postgraduate Studies (Pediatric) of the University of Medicine 2, Yangon.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy area\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMedical units of Yankin Children Hospital\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy population\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll children under one year of age with bronchiolitis were admitted to medical units of Yankin Children Hospital\u003c/p\u003e\n\u003cp\u003eAll children up to one year old with bronchiolitis who fulfilled the inclusion criteria were collected consecutively in all medical wards. After informed written consent was obtained from parents or caregivers, relevant information was collected in pro forma. Moreover, a severity assessment was performed by a researcher to avoid inter-observer variation by using the Wang scoring system. After that, two ml of blood was collected in a plain tube and the sample was sent to YKCH laboratory during 24hours. Serum was obtained after centrifugation at 1500 rpm for 10 minutes. The serum for Vitamin D measurement was stored at -80°C in the YKCH laboratory. The serum samples were transported in a portable cool box with gel refrigerant to the \u0026nbsp;Common Laboratory, University of Medicine 2. \u0026nbsp;Serum vitamin D level was determined by the ELIZA method (Stat Fax 2600 washer and Stat Fax 2100 reader) at the Common Laboratory, University of Medicine 2. Afterward, the collected sample was discarded according to hospital refusal disposal guidelines. Data were collected by using pro forma. To ensure completeness, consistency and correctness, the data collected were checked manually by the interviewers. After the data and code were checked, the data were entered into Microsoft excel 2010. For data validation, a check file was used ,and the data were edited if necessary. Data analysis was performed by using SPSS (Statistical Package for Social Science) 25. Graphs and charts were shown for clear presentation. For continuous data the mean, medium and standard deviation, etc., also were also used to calculate summary measures. Numerical data such as severity score was shown with the mean and standard deviation.\u003c/p\u003e\n\u003cp\u003eEthical Approval\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study followed the research guidelines of the University of Medicine 2(UM 2), Yangon as described in the booklet - Manual for Research Protocol and Dissertation/Thesis Writing, 2019 by UM 2, Yangon. This research protocol was submitted to the Academic Board of Post-graduate Studies (Pediatrics) of the University of Medicine 2, Yangon. This research was carried out only after approval was obtained from the Academic Board of Post graduate Studies (Pediatrics) of University of Medicine 2, Yangon and the \u0026nbsp;ethics review committee of UM (2). All eligible children who met the selection criteria for this study had the chance to participate in this study. Parents or care givers were thoroughly explained in detail about the research by the researcher with a detailed information sheet. Only after they fully understood the nature of the study, including its aim and objectives, methodology, procedures, duration, risks and benefits, and the consent from the parent, were they invited to participate in the study. They reported that minimal side effects such as pain occurred, and this study will benefit directly as well as to help the treatment of upcoming children with bronchiolitis. If they agreed, the written informed consent was obtained. Participation in this research was voluntary. They had the right to refuse to participate in the study and withdraw at any time from the study without any effect. All the standard treatments were continued regardless of the status of the participant in the research. Children with bronchiolitis were closely monitored throughout the research process by the researcher. No money or any forms of abnormal incentives or material goods was supplied to the participants by the researcher for taking part in this study. The investigator strictly maintained the rules of privacy and confidentiality. The history taking, examination and the research work were performed in places with proper privacy. No names were mentioned in this study. Only a coded system was used. The research information was kept in a password-protected file under the care of the investigator. The research data will be used, published and shared for the academic purposes only with no personal identifiers – such as in this dissertation/thesis paper, in medical seminars, conferences and medical publications.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe most affected age group was 1-6 months (86.7%) among study population. However, 13.3% of the study population was between 6 months and 1year old. In terms of sex distribution, 70.7% of the study population was male and 29.3% was female. Although 36% of participants had nonsevere bronchiolitis, 64% of the study population had severe bronchiolitis according to the Wang clinical severity score.\u003c/p\u003e\n\u003cp\u003eApproximately 95% of the patients studied had vitamin D insufficiency and deficiency. Seventy-two percent of the studied population was vitamin D\u0026nbsp;insufficient. A total of 22.7% of the studied children were vitamin D deficient. Only 5.33% were vitamin D sufficient. The mean vitamin D concentrations in nonsevere bronchiolitis and severe bronchiolitis patients in the studied population were 44.29±19.55 nmol/L and 35.31±15.83 nmol/L, respectively. In this study, 94.1% of severe bronchiolitis cases were vitamin D deficient, and only 5.9% of non- severe bronchiolitis cases were vitamin D deficient. A total of 59.3% of severe bronchiolitis were vitamin D insufficient, 40.7% of nonsevere bronchiolitis cases were vitamin D insufficient. All of the vitamin D sufficient patients had non- severe bronchiolitis. Therefore, there was a statistically significant correlation between vitamin D levels and the severity of bronchiolitis (p value \u0026lt;0.5).\u003c/p\u003e\n\u003cp\u003eTable (1)\u003c/p\u003e\n\u003cp\u003eTable (2)\u003c/p\u003e\n\u003cp\u003eTable (3) \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study aims to investigate as the sociation between serum vitamin D levels and the severity of bronchiolitis in children. This is the first study in Myanmar and a hospital-based cross sectional analytical study conducted at Yankin Children’s Hospital from August 2022 to July 2023 after receiving approval from the academic board of the University of Medicine (2). A total of seventy-five children meeting the inclusion criteria were included. The severity of the studied infants was categorized by the Wang severity score, and serum vitamin D levels were determined in the common laboratory of the University of Medicine (2). In this study, the majority of children with severe bronchiolitis were found to be vitamin D deficient.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBackground and clinical characteristics of children with bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eAge distribution of patients with bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 65 children, 86 % of the study population, were in the one-to-six-month-old age group, and only ten children, 13.3 %, were in the six- month- to one-year age group. In the present study, one- to-six-month-old age group was more strongly affected than the six-month to one -year age group was. The minimum age in this study was one month, and the maximum age was 12 months. These findings are consistent with the results of the study by Ye-Kyaw-Thu [8], which revealed that bronchiolitis was most frequent in children in the one- to- six- month age group. This finding is in line with the findings of other international studies. For instance, a study carried out by Golan-Tripto et al [9] in Isreal, a revealed that three to nine months were the most commonly affected age groups. \u0026nbsp;A study carried out by Alakas et al [10], in Turkey also revealed that the age group commonly affected by bronchiolitis was under one year age group. The median age group was 9 months.\u003c/p\u003e\n\u003cp\u003eGender distribution of bronchiolitis\u003c/p\u003e\n\u003cp\u003eIn the present study, males were more affected (70.7%) than females were (29.3%) among the children with bronchiolitis. \u0026nbsp;Slightly larger male populations were found in the Turkey and Isreal studies. In the study by Alakas et al [10], 57.1% of the study population was male and in the study by Golan-Tripto et al [9], 58% of the study population. In contrast, a study by Ye- Kyaw -Thu [8], females were more affected (57.8%).\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eClinical Characteristics of Children with Bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the present study, the clinical parameters were assessed by using the Wang clinical severity score. According to the Wang clinical severity score, severe bronchiolitis was found in 64% of the study population, and nonsevere bronchiolitis was found in 36% of the study population. In contrast to the present study, Rahmati et al [11] used a standard bronchiolitis severity score, which was used to classify as mild, moderate and severe bronchiolitis. In their study, 25.9%, 67.05% and 7.05% of the infants were mild, moderate, severe bronchiolitis, respectively. In the study by Alakas et al [10], infants were assessed by using Modified Tal scoring. In their study, 36.3% of the study population had severe bronchiolitis and 63.7% had mild to moderate bronchiolitis. Various respiratory scores have been used to evaluate the response to acute bronchiolitis in clinical practice and clinical trials. The Wang Respiratory score among the commonly used scores for the assessing \u0026nbsp;the severity of acute bronchiolitis because the physical signs used in these respiratory scores are simple and well categorized.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eVitamin D level\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn this study, the mean vitamin D concentration in the studied population was 38.54±17.67 nmol/L. Our results differed considerably from those of other international studies. In a study by Alakas et al [10], the mean vitamin D concentration in children with bronchiolitis was 50.19±15.32 nmol/L. In a study by Rahmati et al [11], the mean serum level of vitamin D concentration in children with bronchiolitis was 58.74±13.44 nmol/L. Similarly, Beigelman et al [12] reported that the average serum concentration of 25 OH-vitamin D was 75.54 nmol/L. Therefore, the mean vitamin D level in this study was significantly lower than that in other studies.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eVitamin D level and severity of bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, the mean serum vitamin D concentration was 44.29±19.55 nmol/L in nonsevere bronchiolitis patients and 35.31±15.83 nmol/ L in severe bronchiolitis patients. The mean serum vitamin D concentration was greater in patients with non-severe bronchiolitis than in those with severe bronchiolitis. Low serum vitamin D level was significantly associated with severe bronchiolitis. These findings were consistent with those of Rahmati et al [11] study. In their study, 54.1% of their study population had insufficient vitamin D levels and 45.9% of their study population had normal vitamin D levels.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe results of the study by Alakas et al [10] corroborated with those of the present study. Their study revealed that vitamin D deficiency or insufficiency was as high as 47.8% in infants with bronchiolitis. A significantly greater proportion of infants with low vitamin D levels had severe bronchiolitis. Infants admitted to the intensive care unit (40.1%) had significantly greater degrees of vitamin D deficiency or insufficiency. Therefore, Vitamin D deficiency is closely linked to severe bronchiolitis. In the study by Golan-Tripto et al [9] study, vitamin D levels were significantly lower in the bronchiolitis group than in the control group. Deficient vitamin D levels (\u0026lt; 50 nmol/L) were detected in 73 % of the patients in the bronchiolitis group. However, no correlation was found between serum vitamin D levels and bronchiolitis severity, which was assessed by the modified Tal Score and by the length of hospital stay. In a prospective study by Inamo et al [13], serum vitamin D levels were determined in 28 Japanese children hospitalized with \u0026nbsp;lower respiratory tract infections. Infants whosw serum vitamin D concentration was \u0026lt; 10 ng/ml, required supplemental oxygen and ventilator support. Vitamin D deficiency is associated with acute respiratory tract infection because it might be related to its important role in the innate immune system. Vitamin D is involved in inducing the activity of the endogenic antimicrobial proteins, defensins and cathelicidin, which fight against bacterial and viral infections [14]. Cathelicidin is an AMP whose expression is up regulated by 1,25(OH)2D. and plays multiple roles in recent studies. The production of cathelicidin in primary cultures of normal bronchial epithelial cells was reported in recently \u0026nbsp;studies. They were able to demonstrate that 1,25D(OH)2D stimulated the induction of cathelicidin in this cell type. These studies also provided evidence that 1,25D(OH)2D-treated bronchial epithelial cells exhibit increased antibacterial activity [15][16]. Garg et al [15] conducted a five-year case control study in India. In their study, vitamin D deficiency was found in 85.7% of the patients (admitted patients with bronchiolitis, pneumonia and asthma) and only 14.2% of the controls (ambulatory care). Similarly, vitamin D deficiency was higher in the case group (74.19%) than in the control group (25.8%). Therefore, they concluded that low vitamin D levels were significantly correlated with acute lower respiratory tract infections. In the study by Belderbos et al [17] , 54% of the \u0026nbsp;neonate had insufficient vitamin D and 46% of the neonate had sufficient vitamin D. Cord blood vitamin D concentrations were strongly associated with maternal vitamin D3 supplementation during pregnancy. Compare with neonates \u0026nbsp;born with normal vitamin D levels, neonates born with vitamin D insufficiency had a sixfold increased risk of RSV lower respiratory tract infection in the first year of life. In the Hnin Lei Aye [18] study, one- third of the acute respiratory tract infection children in the study had vitamin D insufficiency and deficiency. In the present study, 94.1% of severe bronchiolitis cases were vitamin D deficient, and only 5.9% of non- severe bronchiolitis cases were vitamin D deficient. \u0026nbsp;A total of 59.3% of children with severe bronchiolitis were vitamin D insufficient, and 40.7% of those with nonsevere bronchiolitis were vitamin D insufficient. All of the vitamin D sufficient patients had nonsevere bronchiolitis. Therefore, there was statistically significant association between vitamin D level and severity of bronchiolitis.\u003c/p\u003e"},{"header":"Conclusion and Recommendations","content":"\u003cp\u003eBronchiolitis is among the important causes of acute respiratory illness in children and causes significant morbidity and mortality in infancy. In this study, vitamin deficiency and insufficiency were found in infants with severe bronchiolitis. There is a significant association between vitamin D levels and the severity of bronchiolitis.\u003c/p\u003e\n\u003cp\u003eTherefore, vitamin D supplementation for infants and pregnant mothers should be considered in our country. The American Academy of Pediatrics (AAP) has doubled the recommended intake of vitamin D to 400 IU per day for infants. In this study, all the \u0026nbsp;study patients were admitted to hospital , and thus, \u0026nbsp;further studies should be carried out on mild cases and ambulatory cases.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported from an external grant from the Department of Medical Research (DMR) in \u0026nbsp;Myanmar \u0026nbsp;(DMR Ext Grant 2023/3024).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFinancial interests\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThe authors have no relevant financial or nonfinancial interests to disclose.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAll the authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Dr Myat Myat Khine. The first draft of the manuscript was written by Dr Thet Su Su Aung and all the authors commented on previous versions of the manuscript. All the authors read and approved the final manuscript.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThis study was performed in accordance with the principles of the Declaration of Helsinki. Approval was granted by\u0026nbsp;\u003c/em\u003efrom the Academic Board of Postgraduate Studies (Pediatrics) of the University of Medicine 2, Yangon and the ethic review committee of UM (2), Yangon, Myanmar.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eWritten informed consent was obtained from the parents.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eData are available upon reasonable request to the corresponding author\u0026quot;\u003c/em\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eStockman, Lauren J. MPH; Curns, Aaron T. MPH; Anderson, Larry J. MD; Fischer-Langley, Gayle MD, MPH. Respiratory Syncytial Virus-associated Hospitalizations Among Infants and Young Children in the United States, 1997\u0026ndash;2006. The Pediatric Infectious Disease Journal 31(1):p 5\u0026ndash;9, January 2012. | DOI: 10.1097/INF.0b013e31822e68e6\u003c/li\u003e\n\u003cli\u003eSilver AH, Nazif JM. Bronchiolitis. Pediatr Rev. 2019 Nov;40(11):568\u0026ndash;576. doi: 10.1542/pir.2018-0260. PMID: 31676530.\u003c/li\u003e\n\u003cli\u003eTian J, Wang XY, Zhang LL, Liu MJ, Ai JH, Feng GS, Zeng YP, Wang R, Xie ZD. Clinical epidemiology and disease burden of bronchiolitis in hospitalized children in China: a national cross-sectional study. World J Pediatr. 2023 Sep;19(9):851\u0026ndash;863. doi: 10.1007/s12519-023-00688-9. Epub 2023 Feb 16. PMID: 36795317; PMCID: PMC9933022.\u003c/li\u003e\n\u003cli\u003eRudan I, Boschi-Pinto C, Biloglav Z, Mulholland K, Campbell H. Epidemiology and etiology of childhood pneumonia. Bull World Health Organ. 2008 May;86(5):408\u0026thinsp;\u0026minus;\u0026thinsp;16. doi: 10.2471/blt.07.048769. PMID: 18545744; PMCID: PMC2647437.\u003c/li\u003e\n\u003cli\u003eAkcan, F.A., D\u0026uuml;ndar, Y., Akcan, H.B., Uluat, A., Cebeci, D. and \u0026Uuml;nl\u0026uuml;, İ. (2019) Evaluation of nasal mucociliary clearance time in patients with vitamin-D deficiency. \u003cem\u003eEur Arch Otorhinolaryngol\u003c/em\u003e: 276(4); p.1075\u0026ndash;80. https://doi.org/10.1007/s00405-019-05286-y\u003c/li\u003e\n\u003cli\u003eWalker VP, Modlin RL. The vitamin D connection to pediatric infections and immune function. Pediatr Res. 2009 May;65(5 Pt 2):106R-113R. doi: 10.1203/PDR.0b013e31819dba91. PMID: 19190532; PMCID: PMC2925470.\u003c/li\u003e\n\u003cli\u003eMeltem Erol, H\u0026uuml;seyin Kaya, \u0026Ouml;zlem Bostan Gayret, \u0026Ouml;zg\u0026uuml;l Yiğit, Şahin Hamil\u0026ccedil;ıkan, Emrah Can (2017The Effect of Vitamin D Deficiency on the Severity of Bronchiolitis in Infants. J Pediatr Res:4-1-12(6) DO I: 10.4274/jpr.97658\u003c/li\u003e\n\u003cli\u003eYe-Kyaw-Thu. (2019) Respiratory Synctial virus Genotypes and severity of Bronchiolitis Dr.Med.Sc Thesis, University of Medicine 2, Yangon.\u003c/li\u003e\n\u003cli\u003eGolan-Tripto I, Loewenthal N, Tal A, Dizitzer Y, Baumfeld Y, Goldbart A. Vitamin D deficiency in children with acute bronchiolitis: a prospective cross-sectional case- control study. BMC Pediatr. 2021 Apr 30;21(1):211. doi: 10.1186/s12887-021-02666-4. PMID: 33931018; PMCID: PMC8085105.\u003c/li\u003e\n\u003cli\u003eAlakaş Y, Celiloğlu C, Tolunay O, Matyar S. The Relationship between Bronchiolitis Severity and Vitamin D Status. J Trop Pediatr. 2021 Aug 27;67(4):fmab081. doi: 10.1093/tropej/fmab081. PMID: 34580716.\u003c/li\u003e\n\u003cli\u003eRahmati\u0026lt;?ColorInfoStart FFFFFF?\u0026gt;D\u0026lt;?ColorInfoEnd FFFFFF?\u0026gt;, Mehran AhmadiD, Seyed Alireza SobhaniD, Morteza BakhshiID, HoseinHamadiyanID, Bahareh Alipour (2020), The Relationship Between Serum Vitamin D Level and Severity of Bronchiolitis in Infants Being Referred to in Bandar Abbas Children\u0026rsquo;s Hospital, Iran, Int Electron JMed 2020; 9(3):96\u0026ndash;100. DOI:10.34172/iejm.2020.17\u003c/li\u003e\n\u003cli\u003eBeigelman A, Castro M, Schweiger TL, Wilson BS, Zheng J, Yin-DeClue H, Sajol G, Giri T, Sierra OL, Isaacson-Schmid M, Sumino K, Schechtman KB, Bacharier LB. Vitamin D Levels Are Unrelated to the Severity of Respiratory Syncytial Virus Bronchiolitis Among Hospitalized Infants. J Pediatric Infect Dis Soc. 2015 Sep;4(3):182-8. doi: 10.1093/jpids/piu042. Epub 2014 Jun 5. PMID: 26336601; PMCID: PMC4554201.\u003c/li\u003e\n\u003cli\u003eInamo Y, Hasegawa M, Saito K, Hayashi R, Ishikawa T, Yoshino Y, Hashimoto K, Fuchigami T. Serum vitamin D concentrations and associated severity of acute lower respiratory tract infections in Japanese hospitalized children. Pediatr Int. 2011 Apr;53(2):199\u0026ndash;201. doi: 10.1111/j.1442-200x.2010.03224.x. PMID: 21648117.\u003c/li\u003e\n\u003cli\u003eLeikina E, Delanoe-Ayari H, Melikov K, Cho MS, Chen A, Waring AJ, Wang W, Xie Y, Loo JA, Lehrer RI, Chernomordik LV. Carbohydrate-binding molecules inhibit viral fusion and entry by crosslinking membrane glycoproteins. Nat Immunol. 2005 Oct;6(10):995\u0026ndash;1001. doi: 10.1038/ni1248. Epub 2005 Sep 11. PMID: 16155572.\u003c/li\u003e\n\u003cli\u003eGarg D, Sharma VK, Karnawat BS. Association of serum vitamin D with acute lower respiratory infection in Indian children under 5 years: a case control study. Int JContemp Pediatrics. 2016;3(4):1164-9 DOI: http://dx.doi.org/10.18203/2349-3291.ijcp20163141\u003c/li\u003e\n\u003cli\u003eYim S, Dhawan P, Ragunath C, Christakos S, Diamond G. Induction of cathelicidin in normal and CF bronchial epithelial cells by 1,25-dihydroxyvitamin D(3). J Cyst Fibros. 2007 Nov 30;6(6):403\u0026thinsp;\u0026minus;\u0026thinsp;10. doi: 10.1016/j.jcf.2007.03.003. Epub 2007 Apr 27. PMID: 17467345; PMCID: PMC2099696.\u003c/li\u003e\n\u003cli\u003eBelderbos ME, Houben ML, Wilbrink B, Lentjes E, Bloemen EM, Kimpen JL, Rovers M, Bont L. Cord blood vitamin D deficiency is associated with respiratory syncytial virus bronchiolitis. Pediatrics. 2011 Jun;127(6):e1513-20. doi: 10.1542/peds.2010-3054. Epub 2011 May 9. PMID: 21555499.\u003c/li\u003e\n\u003cli\u003eHnin-Lei-Aye. (2014) Vitamin D level in Children with Pneumonia M.Med.Sc Thesis, University of Medicine 2, Yangon\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eCharacteristics of participants\u003c/p\u003e\n\u003ctable cellspacing=\"0\" cellpadding=\"0\" hspace=\"0\" vspace=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" align=\"left\"\u003e\n \u003cp\u003eCharacteristic of participants (n=75)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cdiv\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"395\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003eCharacteristic of participants\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003en(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 395px;\"\u003e\n \u003cp\u003eAge\u0026nbsp;of presentation\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003e1 month\u0026nbsp;\u0026ndash; 6 months\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e65(86.7)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003e\u0026gt;6\u0026nbsp;months\u0026ndash; 1 year\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e10(13.3)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 395px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMale\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e53(70.7)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFemale\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e22(29.3)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 395px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSeverity of bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003eSevere\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ebronchiolitis\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e48(64)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 283px;\"\u003e\n \u003cp\u003eNon-\u0026nbsp;Severe\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ebronchiolitis\u003c/p\u003e\n \u003cp\u003eSerum vitamin level\u003c/p\u003e\n \u003cp\u003eDeficient\u003c/p\u003e\n \u003cp\u003eInsufficient\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; Sufficient\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e27(36)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e17(22.7)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e54(72)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e4(5.3)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;Serum vitamin D level and severity of bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSeverity of\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eBronchiolitis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" style=\"width: 327px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSerum\u0026nbsp;vitamin\u0026nbsp;D level\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 112px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean\u0026nbsp;\u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRange\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e95%CI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 129px;\"\u003e\n \u003cp\u003eNon severe(n=27)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e44.29\u0026plusmn;19.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e10-100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e36.9 to 51.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003et= - 2.165\u003c/p\u003e\n \u003cp\u003ep value=0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 129px;\"\u003e\n \u003cp\u003eSevere(n=48)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e35.31\u0026plusmn;15.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e7.5-65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e30.34, 39.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 129px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e38.54\u0026plusmn;17.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e7.5-100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e34.5 to 42.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 112px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Association\u0026nbsp;between\u0026nbsp;vitamin\u0026nbsp;D\u0026nbsp;level\u0026nbsp;and\u0026nbsp;severity\u0026nbsp;of bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eSerum\u0026nbsp;vitamin\u0026nbsp;D level(nmol/L)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumber\u0026nbsp;of\u0026nbsp;children\u0026nbsp;with bronchiolitis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNon severe\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ebronchiolitis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSevere\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ebronchiolitis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumber\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePercentage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumber\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePercentage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eNumber \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePercentage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDeficient (\u0026lt;25)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e5.9%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e94.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eInsufficient (25-75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e40.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e59.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSufficient (\u0026gt;75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e36%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e64%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Bronchiolitis, Vitamin D, Infant, Child","lastPublishedDoi":"10.21203/rs.3.rs-9118634/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9118634/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAcute bronchiolitis is the most common lower respiratory tract infection during the first year of life. Vitamin D is an important contributing factor to the increasing incidence and severity of bronchiolitis over the past three decades. Numerous international studies have suggested that low vitamin D levels are associated with the severity of bronchiolitis.\u003c/p\u003e \u003cp\u003ePurpose\u003c/p\u003e \u003cp\u003eThis study aimed to determine serum vitamin D levels in infants hospitalized with acute bronchiolitis in Myanmar.\u003c/p\u003e \u003cp\u003eMethod\u003c/p\u003e \u003cp\u003eA cross-sectional analytical study was conducted in medical units of Yankin Children\u0026rsquo;s Hospital from August 2022 to July 2023. A total of seventy-five children aged one to twelve months old were included and the Wang clinical severity score was assessed for severity categorization. In this study, majority of children with severe bronchiolitis were found to be vitamin D deficient.\u003c/p\u003e \u003cp\u003eResults\u003c/p\u003e \u003cp\u003eA total of 75 children, 86% of the study population, were in the one-to-six-month- old age group and only ten children, 13.3 percent, were in the six-month to one -year-old age group. According to the Wang clinical severity score, severe bronchiolitis was found in 64% of the study population, and non-severe bronchiolitis was detected in 36%.\u003c/p\u003e \u003cp\u003eIn this study, the mean vitamin D level in the studied population was 38.54\u0026thinsp;\u0026plusmn;\u0026thinsp;17.67 nmol/L in non-severe bronchiolitis patients and 35.31\u0026thinsp;\u0026plusmn;\u0026thinsp;15.83 nmol/ L in severe bronchiolitis patients. In the present study, 94.1% of severe bronchiolitis cases were vitamin D deficient, and only 5.9% of none severe bronchiolitis cases were vitamin D deficient. A total of 59.3% of severe bronchiolitis cases were vitamin D insufficient, and 40.7% of non-severe bronchiolitis cases were vitamin D insufficient.\u003c/p\u003e \u003cp\u003eConclusion\u003c/p\u003e \u003cp\u003eAll of the vitamin D sufficient patients had non- severe bronchiolitis. Therefore, there was a statistically significant association between vitamin D levels and the severity of bronchiolitis.\u003c/p\u003e","manuscriptTitle":"Serum Vitamin D Level in Children With Bronchiolitis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-06 18:57:13","doi":"10.21203/rs.3.rs-9118634/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-13T07:57:21+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-11T18:16:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-10T20:17:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"313959812127821097573137921772488494482","date":"2026-04-09T21:01:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"106253074537560326829619364197994992423","date":"2026-04-09T07:23:11+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-28T18:37:57+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-28T18:35:04+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-25T18:19:45+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-24T12:35:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-03-24T12:27:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"68d76302-7e78-4d25-b663-e1755d68e92b","owner":[],"postedDate":"April 6th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":65805785,"name":"Health sciences/Diseases"},{"id":65805786,"name":"Health sciences/Health care"},{"id":65805787,"name":"Biological sciences/Immunology"},{"id":65805788,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2026-05-02T16:08:22+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-06 18:57:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9118634","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9118634","identity":"rs-9118634","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}