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By Rocky Swift and Swati Pandey
March 25 (Reuters) - AstraZeneca said its COVID-19
vaccine was 76% effective in a new analysis of its U.S. trial -
only slightly lower than the level in an earlier report this
week criticised for using outdated data.
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.
VACCINE SEEN AS CRUCIAL
The updated 76% efficacy rate compares with rates of about
95% for vaccines from Pfizer/BioNTech and
Moderna in their trial data.
"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.
Mene Pangalos, an AstraZeneca executive vice-president, said
earlier this week the trial data was encouraging as there were
undoubtedly variants of concern in circulation during the study.
AstraZeneca's vaccine is seen as crucial in tackling the
spread of COVID-19 around the world, not just because of 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.
"What counts will be the FDA assessment and that will be
done based on scrutiny of the full data and not press releases,"
said Stephen Evans, Professor of Pharmacoepidemiology, London
School of Hygiene & Tropical Medicine.
"With completion of the adjudication of events it is
possible, even likely, given the public statement from the DSMB
(Data and Safety Monitoring Board), that the ‘headline’ value
could move slightly further downwards but such variation is not
unexpected."
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 said on Wednesday 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 EU, 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)
