Invasive Haemophilus influenzae Serotype A in the Post-Hib Vaccine Era: A Systematic Review and Meta-analysis

Invasive Haemophilus influenzae Serotype A in the Post-Hib Vaccine Era: A Systematic Review and Meta-analysis | 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 Invasive Haemophilus influenzae Serotype A in the Post-Hib Vaccine Era: A Systematic Review and Meta-analysis Richard Donkor Amponsah, Onyansaniba K. Ntim, Eric S Donkor This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8860456/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 12 You are reading this latest preprint version Abstract The introduction of the Haemophilus influenzae type b (Hib) conjugate vaccine have led to the reduction of Hib infection and emergence of non-b serotypes. We aimed to investigate the prevalence, clinical features, antimicrobial susceptibility, and molecular lineages of Hia disease in the post-Hib vaccine era. A total of 29 eligible studies published up to December 2025 were included. The pooled prevalence of invasive Hia infection was 15.12% (95% CI: 7.81–24.18%), with substantial geographic variation. Prevalence was highest in North America (28.57%) and lowest in Europe (2.16%). Reported incidence ranged from 0.01 to 20.2 cases per 100,000 population, with the greatest burden observed among infants, young children, and Indigenous populations. Meningitis and pneumonia were the most common clinical presentations, and case-fatality rates ranged from 1.9% to 20%. Most isolates remained susceptible to commonly used antibiotics, with β-lactamase–mediated ampicillin resistance less reported (2%). Molecular typing identified 17 sequence types, with ST23 and related lineages predominating across regions. These findings indicate that Hia disease shows heterogeneous geographic distribution, primarily affecting young children, and is characterised by low antimicrobial resistance and a predominance of the ST23 lineage. Health sciences/Diseases Health sciences/Health care Health sciences/Medical research Biological sciences/Microbiology Haemophilus influenzae serotype A Haemophilus influenzae haemophilus influenzae type b vaccine Humans Full Text Additional Declarations No competing interests reported. Supplementary Files Hiasupplementary.docx Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 23 Mar, 2026 Reviews received at journal 22 Mar, 2026 Reviews received at journal 13 Mar, 2026 Reviews received at journal 04 Mar, 2026 Reviewers agreed at journal 02 Mar, 2026 Reviewers agreed at journal 28 Feb, 2026 Reviewers agreed at journal 26 Feb, 2026 Reviewers invited by journal 20 Feb, 2026 Editor assigned by journal 20 Feb, 2026 Editor invited by journal 20 Feb, 2026 Submission checks completed at journal 18 Feb, 2026 First submitted to journal 18 Feb, 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. 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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-8860456","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":595936739,"identity":"5e539fbe-2289-4a7c-9d70-67b8a90a847f","order_by":0,"name":"Richard Donkor Amponsah","email":"","orcid":"","institution":"University of Ghana Medical School","correspondingAuthor":false,"prefix":"","firstName":"Richard","middleName":"Donkor","lastName":"Amponsah","suffix":""},{"id":595936740,"identity":"81c6a434-2152-4577-96c1-916afe47e925","order_by":1,"name":"Onyansaniba K. 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