AstraZeneca says vaccine 76% effective in updated US trial data

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WASHINGTON, March 25, 2021 (BSS/AFP) – British-Swedish drugmaker
AstraZeneca on Wednesday revised down by three percentage points the
effectiveness of its Covid vaccine after American authorities raised concerns
that results reported from its US trial were outdated.

The company now says its vaccine is 76 rather than 79 percent effective at
preventing any kind of symptomatic Covid.

It remains 100 percent effective against severe Covid, it added.

The move came after an independent panel of experts appointed to supervise
the trial expressed concern that AstraZeneca had failed to include updated
data in its initially released figure.

The US National Institutes of Health then issued a highly unusual
statement asking AstraZeneca to work with the panel and issue a new press
release.

“We look forward to filing our regulatory submission for Emergency Use
Authorization in the US and preparing for the rollout of millions of doses
across America,” said Mene Pangalos executive vice president of
biopharmaceuticals research and development.

The new figure is based on 190 people who fell sick among 32,449 trial
participants, two-thirds of whom received the vaccine while the rest received
a placebo.

The previous figure was based on 141 cases, with a cut-off in mid-
February.

The company added there are 14 additional or probable Covid cases left to
be adjudicated.

– Bumpy rollout –

Depending on whether these occurred in the vaccine or placebo group, the
final efficacy figure could go up or down a few percentage points.

The company added the vaccine efficacy in people 65-years-old and over was
85 percent, but the statistical range for this figure — anywhere between 58
and 95 percent — make it less meaningful and the sample size was not
mentioned.

Eight cases of severe Covid occurred — all in the placebo group.

AstraZeneca was an early frontrunner in the global race to develop a Covid
vaccine, and was heavily favored by the United States, which ordered 300
million doses — more than its first orders for Moderna’s and Pfizer’s shots.

But a series of communications blunders eroded US agencies’ confidence.

The US now has three authorized vaccines — Moderna, Pfizer and Johnson &
Johnson — and should have enough supply to more than cover the adult
population by the end of May.

However, authorization by the Food and Drug Administration — considered
the gold standard regulator — would go a long way to calm global doubts over
the AstraZeneca vaccine.

Several European countries paused rollout of the shot over potential blood
clot risks before later resuming its use.

The European Medicines Agency deemed the vaccine safe and said it was not
associated with blood clotting generally — but added it could not rule out a
link to two highly rare forms of clotting, and suggested these risks be
mentioned on a warning label.

The AstraZeneca vaccine is still seen as vital to vaccinating the world
because of its low price and the fact it can be stored long term at fridge
temperatures.

It uses an adenovirus that causes colds in chimpanzees, modified so it
can’t replicate, to carry the gene for a key protein of the coronavirus into
human cells.

The cells then produce that protein on their surface, training the immune
system should it encounter the real virus.