New Study Finds Slightly Elevated Risk of Bleeding Disorders After AstraZeneca Vaccine -- Update
June 09 2021 - 5:12PM
Dow Jones News
By Jenny Strasburg
Researchers studying records of 1.7 million adults who received
the AstraZeneca PLC Covid-19 vaccine in Scotland found a small
increased risk of bleeding conditions also sometimes associated
with several vaccines routinely given to children, and usually
treatable.
The blood disorders are different from a very rare but sometimes
deadly blood-clotting condition that -- coupled with low platelet
levels -- researchers in Europe have already linked to the
AstraZeneca vaccine. That possible side effect has been the focus
of regulatory and government scrutiny in recent months.
In the new paper, published Wednesday in the journal Nature
Medicine, researchers from the U.K. and New Zealand said their
findings shouldn't change policies in the U.K. and elsewhere to
continue deploying the AstraZeneca shot as a generally safe and
effective tool against Covid-19. AstraZeneca and regulators have
said they are studying the blood-clotting matter further and that
the benefits of the shot outweigh risks for most people.
AstraZeneca said Wednesday that more than 500 million doses of the
vaccine have helped save more than 100,000 lives, and that its
safety is paramount.
The new analysis concludes that the benefits of the AstraZeneca
vaccine, along with heightened risks of internal bleeding and blood
clots from Covid-19 itself, far outweighed any increased risks from
the shot for most people. Because incidents of blood clotting have
occurred more often in younger adults, some health officials have
said that they should be offered an alternative to the AstraZeneca
shot.
The vaccine was developed with the University of Oxford. The new
paper, which hasn't been peer reviewed, provides a deeper dive into
a large number of vaccine recipients in a single country. Because
these bleeding conditions have been associated with other,
long-used vaccines, researchers decided to study potential
occurrences in Covid-19 vaccines.
Researchers said the findings show the need for countries to
closely monitor vaccine rollouts to help standardize definitions of
possible side effects and flag problems that might take months or
years to surface.
The study also examined records of around 800,000 people who
received the Pfizer Inc. vaccine, and found no additional risk of
blood clotting or hemorrhaging.
The bleeding risks highlighted in the findings are caused by low
platelet levels brought on by a condition called immune-induced
thrombocytopenia, or ITP. Platelets are blood cells that promote
clotting and prevent bleeding. ITP is rare but has been seen for
years after other common vaccines, including for hepatitis B,
measles, mumps and rubella, the researchers said. They and other
scientists not involved in the study said the condition often goes
undiagnosed and rarely causes death.
Normally the U.K. sees ITP in roughly six to nine people out of
100,000, researchers said Wednesday. Covid-19 has increased that
incidence, making a baseline number difficult to pinpoint in the
pandemic, they said. In the study sample, an additional estimated
1.13 people out of 100,000 experienced the low-platelet condition
after one dose of the AstraZeneca shot.
In total, the Nature study examined records of 2.5 million
people who received their first of two scheduled Covid-19 vaccine
doses in Scotland between Dec. 8 and April 14.
In an accompanying Nature editorial, scientists not involved in
the study said immune-induced thrombocytopenia is often difficult
to diagnose. It is also challenging to separate pre-existing
conditions from the effects of vaccines, they said. "The risk of
vaccination-induced ITP at the rate proposed seems to be far lower
than the many risks associated with Covid-19 itself," they
wrote.
Write to Jenny Strasburg at jenny.strasburg@wsj.com
(END) Dow Jones Newswires
June 09, 2021 17:07 ET (21:07 GMT)
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