Oxford finds COVID-19 shot 76% effective for 3 months after a single dose


Oxford University and AstraZeneca’s COVID-19 vaccine showed in a study it had 76% efficacy against symptomatic infection for three months after a single dose, which increased if the second shot is delayed, backing Britain’s vaccine rollout policy.

The findings of the pre-print paper, which had not been peer-reviewed, supported Britain’s decision to extend the interval between initial and booster doses of the shot to 12 weeks, Oxford said on Tuesday.

However, the new study did not address concerns about a lack of data on efficacy among the oldest, who the British government have given highest priority in its vaccine rollout.

Andrew Pollard, Chief Investigator of the Oxford Vaccine Trial, said the data showed the 12-week interval between doses was “the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose.”