The first dose of COVID-19 vaccination achieved reductions in infection rates of 70% after three weeks, according to a major new analysis.
The findings from King’s College, London, came as a second analysis suggests that 38 million people in the UK now live in communities virtually free of the virus.
The King’s College study also finds that about 25% of vaccine recipients experience mild, short lived systemic side effects, usually lasting no more than two days.
The researchers said that infection risk continued to reduce between 12 and 21 days after vaccination, leading to 69% drop in infection rates after 21 days with the Pfizer vaccine and 60% from the AstraZeneca vaccine.
The findings, reported in The Lancet Infectious Diseases, come from a study of 627,000 volunteers using a symptom study app, ZOE, between December and March this year.
The most common systemic side effect was headache, reported by 7.8% of recipients of the first dose of Pfizer and 22.8% of recipients of the AstraZeneca vaccine.
The study found that people who had earlier suffered from COVID were much more likely to report side-effects.
Researcher Professor Tim Spector said: "The data should reassure many people that in the real world, after effects of the vaccine are usually mild and short-lived, especially in the over 50’s who are most at risk of the infection.
“Rates of new disease are at a new low in the UK according to the ZOE app, due to a combination of social measures and vaccination and we need to continue this successful strategy to cover the remaining population.”
Meanwhile The Times today reports 4,819 of England’s 6,800 statistical areas had fewer than three cases of infection last week, amounting to at least 38 million people living in low risk areas.
The analysis found that Leicester, Kettering, Slough and Manchester had the greatest prevalence of infection, with 75% of the population living in neighbourhoods with more than three cases.
* The UK yesterday reported 2,685 new cases of infection and 17 new deaths from the virus. It is a slight increase on a week earlier when 2,524 new cases were reported.
India, meanwhile, reported 362,000 new cases of infection and 3,285 deaths from the virus.
Vaccine side-effects and SARS-CoV-2 infection after vaccination in users of the COVID Symptom Study app in the UK: a prospective observational study. Lancet Infectious Diseases 27 April 2021
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