Data from the COVID-19 Infection Survey, a partnership between the University of Oxford, the Office of National Statistics (ONS) and the Department for Health and Social Care (DHSC), is the first to show the impact of vaccination on antibody responses and new infections in a large group of adults from the general population aged 16 years and older.
Two studies, released today as pre-prints, focused on the protection from infection provided by COVID-19 vaccines. Researchers analysed 1,610,562 test results from nose and throat swabs taken from 373,402 study participants between 1 December 2020 and 3 April 2021. 21 days after a single dose of either Oxford-AstraZeneca or Pfizer-BioNTech vaccines (with no second dose), the rates of all new COVID-19 infections had dropped by 65%, symptomatic infections by 72% and infections without reported symptoms by 57%.
Reductions in infections and symptomatic infections were even greater after a second dose (70% and 90% respectively), and were similar to effects in those who had previously been infected with COVID-19 naturally. Vaccines were effective against variants compatible with the Kent strain (B.1.1.7). Benefits from vaccines in reducing new infections were similar in older individuals over 75 years and under 75 years, and in those reporting long-term health conditions and not reporting them.