Immunogenicity of Omicron BA.1-adapted BNT162b2 vaccines: randomized trial, 3-month follow-up

Noam Barda, Yaniv Lustig, Victoria Indenbaum, Daniel Zibly, Gili Joseph, Keren Asraf, Yael Weiss-Ottolenghi, Sharon Amit, Limor Kliker, Bayan Abd Elkader, Eytan Ben-Ami, Michal Canetti, Ravit Koren, Shiri Katz-Likvornik, Osnat Halpern, Ella Mendelson, Ram Doolman, Dror Harats, Yitshak Kreiss, Michal MandelboimGili Regev-Yochay

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Objectives: The capability of the SARS-CoV-2 Omicron variant to escape immunity conferred by mRNA vaccines has led to the development of Omicron-adapted vaccines. In this study, we aimed to compare the immune response with the ancestral strain and with the BA.1 Omicron variant after administration of the original vaccine and the Omicron-adapted vaccine. Methods: This is an ongoing phase 3, double-blinded randomized controlled trial, comparing the original BNT161b2 vaccine, monovalent Omicron BA.1-adapted BNT161b2 vaccine, and bivalent combinations. Each vaccine was given at a 30 μg and 60 μg dose. Primary outcomes considered included neutralization titers of SARS-CoV-2 ancestral strain and Omicron BA.1. Exploratory endpoints included neutralization titers for Omicron BA.5, and the incidence of COVID-19 cases. Results: Overall, 122 individuals (22, 19, 20, 20, 20, 20, and 21 in each arm) completed a 90-day follow-up. Three months after vaccination, adjusting for baseline levels, neutralizing antibody titers were 0.63 (95% CI: 0.3–1.32) and 0.54 (0.24–1.2) for monovalent/60 μg, 0.9 (0.42–1.92) and 2.69 (1.17–6.17) times for monovalent-Omi.BA.1/30 μg, 1.28 (0.6–2.75) and 2.79 (1.21–6.41) times for monovalent-Omi.BA.1/60 μg, 0.96 (0.46–1.97) and 2.07 (0.93–4.58) times for bivalent-Omi.BA.1/30 μg, and 0.79 (0.38–1.63) and 1.95 (0.88–4.32) times for bivalent-Omi.BA.1/60 μg when compared with BNT162b2/30 μg against the ancestral strain and BA.1 variant, respectively. Discussion: : BA.1-adapted mRNA vaccines lead to a stronger neutralizing antibody response against the Omicron BA.1 sub-variant.

Original languageEnglish
Pages (from-to)918-923
Number of pages6
JournalClinical Microbiology and Infection
Issue number7
StatePublished - Jul 2023


  • COVID-19
  • Immunogenicity
  • Omicron
  • Vaccine

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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