Population antibody responses following COVID-19 vaccination in 212,102 individuals

Population antibody surveillance helps track immune responses to COVID-19 vaccinations at scale, and identify host factors that may affect antibody production. We analyse data from 212,102 vaccinated individuals within the REACT-2 programme in England, which uses self-administered lateral flow antibody tests in sequential cross-sectional community samples; 71,923 (33.9%) received at least one dose of BNT162b2 vaccine and 139,067 (65.6%) received ChAdOx1. For both vaccines, antibody positivity peaks 4-5 weeks after first dose and then declines. At least 21 days after second dose of BNT162b2, close to 100% of respondents test positive, while for ChAdOx1, this is significantly reduced, particularly in the oldest age groups (72.7% [70.9-74.4] at ages 75 years and above). For both vaccines, antibody positivity decreases with age, and is higher in females and those with previous infection. Antibody positivity is lower in transplant recipients, obese individuals, smokers and those with specific comorbidities. These groups will benefit from additional vaccine doses. The authors present results from the REACT-2 study, a series of cross-sectional community surveys during the SARS-CoV-2 pandemic in England. They measure antibodies by self-administered lateral flow tests and describe antibody positivity by time since vaccination, age, sex, co-morbidities, infection history, and vaccine type.

Automated summary

Population antibody surveillance is crucial for tracking immune responses to COVID-19 vaccinations. The study found that antibody positivity peaks 4-5 weeks after the first dose of the vaccine and then declines. Age, gender, comorbidities, and infection history affect antibody positivity rates.