The pronounced decline of anti-SARS-CoV-2 spike trimeric IgG and RBD IgG in baseline seronegative individuals 6 months after BNT162b2 vaccination is consistent with the need for vaccine boosters

The pronounced decline of anti-SARS-CoV-2 spike trimeric IgG and RBD IgG in baseline seronegative individuals 6 months after BNT162b2 vaccination is consistent with the need for vaccine boosters | 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 Short Report The pronounced decline of anti-SARS-CoV-2 spike trimeric IgG and RBD IgG in baseline seronegative individuals 6 months after BNT162b2 vaccination is consistent with the need for vaccine boosters Gian Luca Salvagno, Brandon M. Henry, Laura Pighi, Simone De Nitto, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1063499/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: This observational retrospective study aimed to define the kinetics of serum levels of anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) spike trimeric and anti-receptor binding domain (RBD) IgG antibodies up to 6 months after BNT162b2 vaccination. Methods: The sample consisted of 86 SARS-CoV-2 baseline seronegative subjects (median age 45 years, IQR 31-53 years; 52.3% females) undergoing vaccination with Pfizer/BioNTech BNT162b2. Blood was drawn before receiving the first and the second vaccine dose, as well as 1, 3 and 6 months after the second vaccine dose. The serum levels of anti-SARS-CoV-2 spike trimeric IgG and RBD IgG antibodies were assayed. Results: The peak of both antibodies types was reached 1 month after the second dose (2808 and 2163 BAU/mL for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG), after which serum levels progressively declined, falling after 6 months to 486 BAU/mL and 167 BAU/mL for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG, respectively. The median rate of 6-month decline was 85% and 93% for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG, respectively. The rate of vaccine recipients with serum antibodies levels above the 80% threshold of vaccine efficacy declined from over 95% at the peak to 72% and 5% at 6 months for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG, respectively. Conclusions: The results of this retrospective observational study are consistent with the need for timely administration of vaccine boosters to prevent that humoral immunity will wane. Virology COVID-19 SARS-CoV-2 Vaccination Antibodies Immune response Full Text Cite Share Download PDF Status: Posted Version 1 posted 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-1063499","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Short Report","associatedPublications":[],"authors":[{"id":62221798,"identity":"891cfdd6-263a-4c54-a7c1-d811b5d67b76","order_by":0,"name":"Gian Luca Salvagno","email":"","orcid":"","institution":"Section of Clinical Biochemistry, University of Verona, Verona, Italy and Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Gian","middleName":"Luca","lastName":"Salvagno","suffix":""},{"id":62221801,"identity":"b12d7444-b8e2-4280-be81-dfe25ce64c05","order_by":1,"name":"Brandon M. 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vaccination.\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u003cstrong\u003e\u003cem\u003eMethods:\u003c/em\u003e\u003c/strong\u003e The sample consisted of 86 SARS-CoV-2 baseline seronegative subjects (median age 45 years, IQR 31-53 years; 52.3% females) undergoing vaccination with Pfizer/BioNTech BNT162b2. Blood was drawn before receiving the first and the second vaccine dose, as well as 1, 3 and 6 months after the second vaccine dose. The serum levels of anti-SARS-CoV-2 spike trimeric IgG and RBD IgG antibodies were assayed.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003e\u003cem\u003eResults: \u003c/em\u003e\u003c/strong\u003eThe peak of both antibodies types was reached 1 month after the second dose (2808 and 2163 BAU/mL for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG), after which serum levels progressively declined, falling after 6 months to 486 BAU/mL and 167 BAU/mL for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG, respectively. The median rate of 6-month decline was 85% and 93% for anti-SARS-CoV-2 spike trimeric IgG and RBD IgG, respectively. 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