Antibody responses to SARS-CoV-2 vaccines in 45,965 adults from the general population of the United Kingdom

TLDR

The study proposes prioritizing vaccine administration for individuals without prior infection and recommending second doses for those over 60 years. In a cohort of 45,965 adults, a single dose of ChAdOx1 or BNT162b2 produced lower seroconversion rates and antibody levels in older individuals (>60 years), with BNT162b2 showing slower rise and waning in older adults, while two doses achieved high responses across all ages; latent class analysis identified a low‑responder subgroup mainly comprising people >75, males, and those with long‑term health conditions. Further data are needed to better understand the extent to which quantitative antibody responses are associated with vaccine‑mediated protection.

Abstract

Abstract We report that in a cohort of 45,965 adults, who were receiving either the ChAdOx1 or the BNT162b2 SARS-CoV-2 vaccines, in those who had no prior infection with SARS-CoV-2, seroconversion rates and quantitative antibody levels after a single dose were lower in older individuals, especially in those aged >60 years. Two vaccine doses achieved high responses across all ages. Antibody levels increased more slowly and to lower levels with a single dose of ChAdOx1 compared with a single dose of BNT162b2, but waned following a single dose of BNT162b2 in older individuals. In descriptive latent class models, we identified four responder subgroups, including a ‘low responder’ group that more commonly consisted of people aged >75 years, males and individuals with long-term health conditions. Given our findings, we propose that available vaccines should be prioritized for those not previously infected and that second doses should be prioritized for individuals aged >60 years. Further data are needed to better understand the extent to which quantitative antibody responses are associated with vaccine-mediated protection.