TY - JOUR
AU - Kerr, Steven
AU - Bedston, Stuart
AU - Bradley, Declan T.
AU - Joy, Mark
AU - Lowthian, Emily
AU - Mulholland, Rachel H.
AU - Akbari, Ashley
AU - Hobbs, F.D. Richard
AU - Katikireddi, Srinivasa Vittal
AU - de Lusignan, Simon
AU - Rudan, Igor
AU - Torabi, Fatemeh
AU - Tsang, Ruby S.M.
AU - Lyons, Ronan A.
AU - Robertson, Chris
AU - Sheikh, Aziz
PY - 2022
DA - October
TI - Waning of first- and second-dose ChAdOx1 and BNT162b2 COVID-19 vaccinations: a pooled target trial study of 12.9 million individuals in England, Northern Ireland, Scotland and Wales
JO - International Jourrnal of Epidemiology
DO - https://doi.org/10.1093/ije/dyac199
AB - Background:  Several SARS-CoV-2 vaccines have been shown to provide protection against COVID-19 hospitalization and death. However, some evidence suggests that notable waning in effectiveness against these outcomes occurs within months of vaccination. We undertook a pooled analysis across the four nations of the UK to investigate waning in vaccine effectiveness (VE) and relative vaccine effectiveness (rVE) against severe COVID-19 outcomes. Methods:  We carried out a target trial design for first/second doses of ChAdOx1(Oxford–AstraZeneca) and BNT162b2 (Pfizer–BioNTech) with a composite outcome of COVID-19 hospitalization or death over the period 8 December 2020 to 30 June 2021. Exposure groups were matched by age, local authority area and propensity for vaccination. We pooled event counts across the four UK nations. Results:  For Doses 1 and 2 of ChAdOx1 and Dose 1 of BNT162b2, VE/rVE reached zero by approximately Days 60–80 and then went negative. By Day 70, VE/rVE was –25% (95% CI: –80 to 14) and 10% (95% CI: –32 to 39) for Doses 1 and 2 of ChAdOx1, respectively, and 42% (95% CI: 9 to 64) and 53% (95% CI: 26 to 70) for Doses 1 and 2 of BNT162b2, respectively. rVE for Dose 2 of BNT162b2 remained above zero throughout and reached 46% (95% CI: 13 to 67) after 98 days of follow-up. Conclusions:  We found strong evidence of waning in VE/rVE for Doses 1 and 2 of ChAdOx1, as well as Dose 1 of BNT162b2. This evidence may be used to inform policies on timings of additional doses of vaccine.
PB - Oxford University Press
UR - https://strathprints.strath.ac.uk/82890/
KW - Coronavirus (COVID-19)
KW - Immunisation and screening
ER