Summary
This prospective observational study tracked vaccine safety and effectiveness in 627,383 UK residents vaccinated between December 2020 and March 2021. Systemic side-effects occurred in 13.5% after first BNT162b2 dose, 22.0% after second BNT162b2 dose, and 33.7% after first ChAdOx1 nCoV-19 dose; local side-effects were considerably more frequent. Both vaccines demonstrated significant protection against SARS-CoV-2 infection, reaching 60–72% risk reduction by 21+ days post-vaccination depending on vaccine type and timing. The findings provide real-world evidence of tolerability and effectiveness outside phase 3 trial conditions.
UK applicability
The findings are directly applicable to UK policy and practice as the study was conducted in the UK community setting during the national vaccination rollout. The data informed understanding of expected side-effect profiles and vaccine effectiveness during the ongoing immunisation programme.
Key measures
Proportions of individuals reporting local side-effects (injection site reactions) and systemic side-effects (fever, fatigue, headache, etc.) by vaccine type and dose; risk reduction for SARS-CoV-2 infection at specified intervals post-vaccination; comparison between vaccinated individuals and unvaccinated controls
Outcomes reported
The study measured the frequency and nature of local and systemic side-effects following vaccination with BNT162b2 and ChAdOx1 nCoV-19 vaccines, and assessed vaccine effectiveness against SARS-CoV-2 infection in a large UK community cohort.
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