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By Ludwig Burger and Matthias Blamont
FRANKFURT/PARIS, March 18 (Reuters) - Europe's medicines
watchdog concluded on Thursday that AstraZeneca's
coronavirus vaccine still far outweighed any risks after
investigating reports of rare blood clotting disorders but said
it would add a warning to the product leaflet.
"A causal link with the vaccine is not proven, but is
possible and deserves further analysis," the European Medicines
Agency (EMA) said.
The World Health Organization has previously also said there
was no proven link and that the benefits far outweighed any
risks.
At least 13 EU member states including Germany, France and
Italy have suspended use of the shot pending the outcome of
EMA's probe.
Here's what we know so far:
WHAT HAS HAPPENED?
More than 45 million shots by various manufacturers have
been administered across the EU and the European Economic Area
since vaccinations started almost three months ago. The
AstraZeneca vaccine was given to 5 million people in the EU.
EMA said it had reviewed seven cases of blood clots in
multiple blood vessels, called disseminated intravascular
coagulation (DIC) and 18 cases of cerebral venous sinus
thrombosis (CVST) in people who had received the AstraZeneca
shot, most of whom were women.
In Germany, eight people have been diagnosed with CVST
within about two weeks of vaccination among the 1.6 million
recipients of the shot as of Wednesday, according to the health
ministry. Normally 1 to 1.4 cases would have been expected
during that time, the ministry added.
Germany's vaccine authority Paul Ehrlich Institute (PEI) has
said the majority of the cases were young to middle-aged women
and that there had been three deaths.
WHAT HAVE OTHER COUNTRIES AND ASTRAZENECA SAID?
In Britain, where more than 11 million doses of the
AstraZeneca vaccine have been administered, the medicines
regulator said on Thursday it was investigating five cases of
CVST among recipients but it reiterated that the benefits of the
shot far outweighed any possible risks.
Canada has said health experts are sure all COVID-19
vaccines being administered in the country are safe, including
AstraZeneca's.
AstraZeneca said on Sunday a review of safety data of more
than 17 million people vaccinated in the United Kingdom and
European Union with its vaccine had shown no evidence of an
increased risk of blood clots.
?
WHAT WAS THE EMA INVESTIGATING?
EMA investigators checked if the frequency of incidences was
higher in the vaccinated population than normal background
rates.
The normal frequency is drawn from public health statistics
or insurance records. This would be combined with a medical
analysis of each case and insight from scientific literature.
EMA's head of safety monitoring, Peter Arlett, said on
Tuesday the rarity of CVST meant the watchdog would have to rely
more heavily on case-by-case analysis rather than on statistical
data.
A spokeswomen for Germany's vaccine authority, which is part
of the investigation, said prior to the safety review that EMA
would not rule on causality.
Instead, EMA would assess the likelihood of an increased
risk of the condition and weigh that against the benefits of
fighting COVID-19.
For example, the vaccines developed by Pfizer and
Moderna have been linked with increased risk of
anaphylaxis, but they are still recommended because benefits
outweigh the risks of the side effect, which can be treated.
WHAT DID THE CLINICAL TRIALS SHOW?
AstraZeneca and European regulators have said that concerns
about blood coagulation disorders did not emerge during human
trials.
Safety monitoring after approval is key because extremely
rare side-effects, or those affecting only a small subset of the
population, are near impossible to identify during clinical
trials, according to Germany's PEI.
ARE THERE PRECEDENTS OF VACCINE SAFETY SCARES?
In Japan, a governmental recommendation for use of human
papillomavirus (HPV) vaccine to prevent cervical cancer has been
suspended since June 2013, due to media reports of an alleged
pain syndrome. This has drawn criticism from the WHO.
A study published in The Lancet Public Health last year
concluded a continued suspension would lead to thousands of
cancer deaths over the next decades.
In Ukraine, deep mistrust of vaccines has allowed measles to
grow into an epidemic. Vaccine hesitancy there is rooted in
corruption and mistrust of authority but also in a temporary
government suspension in 2008, when a 17-year-old boy died
shortly after receiving a measles-rubella vaccine.
(Reporting by Ludwig Burger and Matthias Blamont
Additional reporting by Kate Kelland in London and Julie
Steenhuysen in Chicago
Editing by Josephine Mason, Nick Macfie, Elaine Hardcastle and
Frances Kerry)
