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* Estimated 89% effectiveness against symptomatic disease
* Analysis is first to study two AZ doses in real setting
* But PHE has "low confidence" in result until more data
collected
* Pfizer shot effectiveness drops off 10 weeks after first
dose
(Adds AstraZeneca statement)
By Alistair Smout
LONDON, May 20 (Reuters) - Two doses of the
Oxford/AstraZeneca COVID-19 vaccine may be around 85% to 90%
effective against symptomatic disease, Public Health England
(PHE) said on Thursday, while cautioning that it did not yet
have enough data to be conclusive.
Britain has suffered one of the worst death tolls globally
from the pandemic, but has also had one of the fastest vaccine
rollouts, generating a lot of data about the use of the shots in
real-world settings.
It was the first country to roll out AstraZeneca's
vaccine, which faced questions over the construction of its
clinical trials, the efficacy of the vaccine and the optimal gap
between doses of its shot.
PHE said the preliminary findings were the first of its kind
on the effectiveness of two doses of AstraZeneca in a real-world
setting but cautioned that it had "low confidence" in the
findings, and the results would be inconclusive until more
evidence was gathered.
In a weekly surveillance report, Public Health England said
the estimated effectiveness of the AstraZeneca vaccine, invented
at the University of Oxford, was 89% compared to unvaccinated
people.
That compares to 90% estimated effectiveness against
symptomatic disease for the Pfizer/BioNTech
vaccine.
"This new data highlights the incredible impact that both
doses of the vaccine can have, with a second dose of the
Oxford/AstraZeneca vaccine providing up to 90% protection,"
vaccines minister Nadhim Zahawi said.
AstraZeneca welcomed the preliminary findings.
"This latest real-world data from PHE adds to the growing
body of evidence that demonstrates the effectiveness of our
vaccine against COVID-19," a spokesman said.
"It is reassuring to see the data from both the Pfizer and
Oxford AstraZeneca vaccines. They are essentially comparable in
terms of effectiveness against symptomatic disease, which is
very high after two doses," said Michael Head, Senior Research
Fellow in Global Health at the University of Southampton.
Britain has been rolling out the shots manufactured by
Pfizer and AstraZeneca since December and January respectively,
and in April also started deploying Moderna's vaccine.
PHE said there was a "small reduction in vaccine
effectiveness" from 10 weeks after the first dose of the Pfizer
shot before the second shot is given.
Britain extended the gap between doses to 12 weeks, though
Pfizer warned there was a lack of evidence of its efficacy
outside the three-week gap used in trials.
Last week, Britain cut the gap between doses down to 8 weeks
for the over 50s, aiming to give maximum protection to more
vulnerable people in light of concern about the B.1.617.2
variant first found in India.
(Reporting by Alistair Smout; Editing by Kate Holton and Giles
Elgood)
