Oxford Covid Vaccine Protects Three Months After One Dose And May Reduce Transmission
The jab could have a "substantial effect" on reducing transmission of coronavirus, Oxford University analysis finds.
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One jab of the Oxford University and AstraZeneca vaccine offers 76% protection against Covid-19 for up to three months, a study has shown.
The finding is a boost for Britain’s controversial decision to extend the gap between the first and second doses of the vaccine to 12 weeks.
Oxford University said the findings of the pre-print paper show the jab also had a “substantial effect” on reducing transmission of the disease.
Before these results, little was known about how effective the Covid-19 vaccines were at preventing transmission of the disease.
Britain has decided to give as many people as possible some protection by lengthening the amount of time between initial shots and booster shots of Covid-19 vaccines.
Oxford academics said: “Vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 post vaccination was 76%, and modelled analysis indicated that protection did not wane during this initial three month period.”
The paper said that vaccine efficacy was 82.4% with 12 or more weeks to the second dose, compared to 54.9% for those where the booster was given under six weeks after the first dose.
The authors also reported a 67% reduction in transmission after the first dose of the vaccine based on swabs obtained from volunteers in the UK arms of the trial.
The report states that the vaccine “may have a substantial impact on transmission by reducing the number of infected individuals in the population”.
The results, gathered from trials in Britain, Brazil and South Africa, indicated that immune responses were boosted with a longer interval to the second dose among participants aged 18 to 55 years.
Professor Andrew Pollard, chief investigator of the Oxford Vaccine Trial, and study co-author, said: “These new data provide an important verification of the interim data that was used by more than 25 regulators including the MHRA (Medicines and Healthcare products Regulatory Agency) and EMA (European Medicines Agency) to grant the vaccine emergency use authorisation.
“It also supports the policy recommendation made by the Joint Committee on Vaccination and Immunisation (JCVI) for a 12-week prime-boost interval, as they look for the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose of the vaccine.”