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 Interim data published on Monday had put the vaccine's efficacy rate
at 79% but had not included more recent infections, leading to a
highly unusual public rebuke from U.S health officials.
The small revision to the efficacy rate will go a long way to
putting the vaccine back on track for gaining U.S. emergency use
authorisation - which it plans to seek in the coming weeks - and
help AstraZeneca in its efforts to dispel doubts about its
effectiveness and side-effects, independent experts said.
AstraZeneca also reiterated that the shot, developed with Oxford
University, was 100% effective against severe or critical forms of
the disease. There have been eight severe cases - all among trial
participants who received the placebo.
"The vaccine efficacy against severe disease, including death, puts
the AZ vaccine in the same ballpark as the other vaccines," said
William Schaffner, an infectious disease expert from the Vanderbilt
University School of Medicine, adding that he expects the shot to
gain U.S. approval.
The latest data was based on 190 infections among more than 32,400
participants in the United States, Chile and Peru. The earlier
interim data was based on 141 infections through Feb. 17.
It also said the vaccine showed 85% efficacy in adults 65 years and
older, higher than the 80% rate reported on Monday.
AstraZeneca said the latest data has been presented to the
independent trial oversight committee, the Data Safety Monitoring
Board, and it plans to submit the analysis for peer-reviewed
publication in the coming weeks.
"The primary analysis is consistent with our previously released
interim analysis, and confirms that our COVID-19 vaccine is highly
effective in adults," Mene Pangalos, executive vice president of
BioPharmaceuticals R&D at AstraZeneca said in a statement.
The drugmaker noted there were 14 additional possible or probable
cases to be analysed so numbers in later updates of the trial
results may fluctuate slightly.
The updated 76% efficacy rate compares with rates of about 95% for
vaccines from Pfizer/BioNTech and Moderna in their trial data.
Experts have noted, however, that AstraZeneca's latest data is
particularly significant because it was compiled after more
infectious variants of the coronavirus became prevalent.
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 "This appears to be a very
effective vaccine with no safety concerns," said
Paul Griffin, a professor at the University of
Queensland.
"Hopefully, this should now give people the
confidence that this vaccine is the right one to
continue to use moving forward," he said, adding
that he and his parents have received the
vaccine.
AstraZeneca's vaccine is seen as crucial in
tackling the spread of COVID-19 across the
globe, not just due to limited supply of
vaccines but also because it is easier and
cheaper to transport than rival shots. It has
been granted conditional marketing or emergency
use authorisation in more than 70 countries.
The vaccine, once hailed as a milestone in the fight
against the COVID-19 pandemic, has been dogged by questions since
late last year when the drugmaker and Oxford University published
data from an earlier trial with two different efficacy readings as a
result of a dosing error.
Then this month, more than a dozen countries temporarily suspended
giving out the vaccine after reports linked it to a rare blood
clotting disorder in a very small number of people.
The European Union's drug regulator said last week the vaccine was
clearly safe, but Europeans remain sceptical about its safety.
Canada on Wednesday said it was safe but added a warning to the
vaccine's label about rare blood clots.
Its rollout has also been marred by production glitches and export
curbs imposed by India and the European Union, threatening to slow
global efforts to end the pandemic which has killed more than 2.8
million.
(Reporting by Rocky Swift in Tokyo, Swati Pandey in Sydney, Peter
Henderson in San Francisco and Shubham Kalia in Bengaluru; Writing
by Miyoung Kim; Editing by Edwina Gibbs)
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