Early Immunogenicity and Safety of the Third Dose of BNT162b2 Messenger RNA Coronavirus Disease 2019 Vaccine among Adults Older Than 60 Years: Real-World Experience

Mayan Gilboa, Michal Mandelboim, Victoria Indenbaum, Yaniv Lustig, Carmit Cohen, Galia Rahav, Keren Asraf, Sharon Amit, Hanaa Jaber, Ital Nemet, Limor Kliker, Erez Bar-Haim, Ella Mendelson, Ram Doolman, Carmit Rubin, Gili Regev-Yochay, Yitshak Kreiss

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Background: Despite high vaccine coverage, an increase in breakthrough coronavirus disease 2019 (COVID-19) infections, prompted administration of a third BNT162b2 dose to people aged >60 years in Israel since July 2021. Here, we report real-world immunogenicity following third dose. Methods: Overall, 208 healthcare workers aged >60 years were included. Paired pre- and post-second and/or third dose immunoglobulin G (IgG) and neutralizing antibody titers were compared. A subpopulation of low responders to the second dose was also tested for T-cell activation. For 25 paired serum samples, we tested neutralization of wild-type vs neutralization of Delta and Lambda variants, pre- and post-third dose. Active surveillance of vaccine adverse events was conducted through surveys. Results: A pronounced immune response was observed following the third dose, including a 33-fold and 51-fold increase in IgG and neutralizing antibody, respectively. The neutralizing antibody levels post-third dose were 9.34 times higher than post-second dose (geometric mean titer, 2598 [95% confidence interval {CI}, 2085-3237] vs 207 [95% CI, 126-339]). Nine previously low responders had a significant antibody increase post-third dose, and 7 of 9 showed increase in T-cell activation. Additionally, sera obtained post-third dose highly and comparably neutralized the wild-type and Delta and Lambda variants. Of 1056 responders to the adverse-event survey, none had serious events. Conclusions: We demonstrate a rapid and broad immune response to the third BNT162b2 dose in individuals >60 years of age.

Original languageEnglish
Pages (from-to)785-792
Number of pages8
JournalJournal of Infectious Diseases
Volume225
Issue number5
DOIs
StatePublished - 2 Mar 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2021 The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: [email protected].

Keywords

  • BNT162b2
  • COVID-19
  • boosting effect
  • elderly
  • third dose

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