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LONDON, Feb 2 (Reuters) - The COVID-19 vaccine developed by
Oxford University and AstraZeneca has 76% efficacy against
symptomatic infection for three months after a single dose, with
greater effectiveness when a second is given later, a study
showed on Tuesday.
Oxford University said 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which had not been peer-reviewed, supported Britain's decision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.
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.
AstraZeneca has welcomed the move, saying flexibility to
extend the time between doses is the best strategy for the shot.
The results, gathered from trials in Britain, Brazil and
South Africa, indicated some protection was given after one shot
and that immune responses were boosted with a longer interval to
the second dose among participants aged 18 to 55 years.
"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 3 month period," Oxford academics said.
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 6 weeks after the first dose.
(Reporting by Alistair Smout
Editing by Gareth Jones and Alexander Smith)
