Immunity against conserved epitopes dominates after two consecutive exposures to SARS-CoV-2 Omicron BA.1.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure histories become increasingly complex through original and variant-adapted vaccines and infections with viral variants. Upon exposure to the highly altered Omicron spike glycoprotein, pre-immunized individuals predominantly mount recall responses of Wuhan-Hu-1 (wild-type)-imprinted memory B (B) cells mostly targeting conserved non-neutralizing epitopes, leading to diminished Omicron neutralization. We investigated the impact of imprinting in individuals double/triple vaccinated with a wild-type-strain-based mRNA vaccine who, thereafter, had two consecutive exposures to Omicron BA.

Immunogenicity and safety of BNT162b2 mRNA vaccine in Chinese adults: A phase 2 randomised clinical trial.

Background: BNT162b2, an mRNA vaccine against COVID-19, is being utilised worldwide, but immunogenicity and safety data in Chinese individuals are limited.

Methods: This phase 2, randomised, double-blind, placebo-controlled trial included healthy or medically stable individuals aged 18-85 years enrolled at two clinical sites in China. Participants were stratified by age (≤55 or >55 years) and randomly assigned (3:1) by an independent randomisation professional to receive two doses of intramuscular BNT162b2 30 μg or placebo, administered 21 days apart.

Immune Persistence and Safety After SARS-CoV-2 BNT162b1 mRNA Vaccination in Chinese Adults: A Randomized, Placebo-Controlled, Double-Blind Phase 1 Trial.

Introduction: BNT162b1 is a lipid nanoparticle-formulated, nucleoside-modified mRNA SARS-CoV-2 vaccine. Here, we report safety and immune persistence data following a primary two-dose vaccination schedule administered 21 days apart.

Methods: Immune persistence was determined at month 3 in 72 younger participants (aged 18-55 years) and at month 6 in 70 younger and 69 older participants (aged 65-85 years).

Neutralization of SARS-CoV-2 Omicron by BNT162b2 mRNA vaccine-elicited human sera.

The globally circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concern Omicron (B.1.1.