AstraZeneca Covid-19 vaccine is 76 percent effective 12 weeks after first dose – Oxford study

The Covid-19 vaccine made by AstraZeneca and the University of Oxford is 76 percent effective against the virus 12 weeks after it is given as a single dose, scientists from the university said on Tuesday.

Their findings, in a preprint study that is yet to be peer reviewed, also show that the efficacy of the jab improves to 82.4 percent when a second shot is administered 12 weeks after the first.

The study, published by the University of Oxford in scientific journal the Lancet, also shows a 67 percent decrease in the number of people testing positive among those given the vaccine.

The data bolsters the UK government's Covid-19 vaccination strategy to administer second doses up to 12 weeks after the first, in an effort to give the initial dose of the vaccine to as many people as possible in a shorter time period.

The UK's four chief medical officers announced the strategy in December for deploying both the AstraZeneca-Oxford and Pfizer-BioNTech jabs.

The move was authorised by the government's Medicines and Healthcare products Regulatory Agency (MHRA).

But the 12-week dosing regimen contrasts with Pfizer's own recommendations for vaccine use, which say that the two shots should be given 21 days apart to guarantee its efficacy of 95 percent.

The UK has now vaccinated more than 10 million people against the virus, with the majority of those given the first dose of one of its three vaccines approved in the country to date – Pfizer, AstraZeneca and Moderna.

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