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ROME, April 6 (Reuters) - There is a link between
AstraZeneca's COVID-19 vaccine and very rare blood clots
in the brain but the possible causes are still unknown, a senior
official for the European Medicines Agency (EMA) said in an
interview published on Tuesday.
"In my opinion we can now say it, it is clear that there is
an association with the vaccine. However, we still do not know
what causes this reaction," Marco Cavaleri, chair of the vaccine
evaluation team at the EMA, told Italian daily Il Messaggero
when asked about the possible relation between the AstraZeneca
shot and cases of brain blood clots.
Cavaleri added that the EMA would say there is a link
although the regulator would not likely be in a position this
week to give an indication regarding the age of individuals to
whom the AstraZeneca shot should be given.
He did not provide evidence to support his comments.
AstraZeneca was not immediately available for comment. It
has said previously its studies have found no higher risk of
clots because of the vaccine.
The regulator has consistently said the benefits outweigh
the risks as it investigates 44 reports of an extremely rare
brain clotting ailment known as cerebral venous sinus thrombosis
(CVST) out of 9.2 million people in the European Economic Area
who have received the AstraZeneca vaccine.
The World Health Organization has also backed the vaccine.
The EMA said last week that its review had at present not
identified any specific risk factors, such as age, gender or a
previous medical history of clotting disorders, for these very
rare events. A causal link with the vaccine is not proven, but
is possible and further analysis is continuing, the agency said.
A high proportion among the reported cases affected young
and middle-aged women but that did not lead EMA to conclude this
cohort was particularly at risk from AstraZeneca's shot.
The EMA is expected to give an update of its investigation
on Wednesday.
Some countries, including France, Germany and the
Netherlands, have suspending the use of the vaccine in younger
people while the investigations continue.
Scientists are exploring several possibilities that might
explain the extremely rare brain blood clots that occurred in
individuals in the days and weeks after receiving the
AstraZeneca vaccine.
European investigators have put forward one theory that the
vaccine triggers an unusual antibody in some rare cases; others
are trying to understand whether the cases are linked with birth
control pills.
But many scientists say there is no definitive evidence and
it is not clear whether or why AstraZeneca's vaccine would cause
an issue not shared by other vaccines that target a similar part
of the coronavirus.
In a separate interview, Armando Genazzani, a member of the
EMA's Committee for Medicinal Products for Human Use (CHMP),
told La Stampa daily that it was "plausible" that the blood
clots were correlated to the AstraZeneca vaccine.
(Reporting by Giulia Segreti; Editing by Giles Elgood)
