EUROPE’s medical regulators, European Medicines Agency (EMA) today (Wednesday, April 7, 2021) said that rare but sometimes deadly blood clots are a potential side effect of AstraZeneca’s coronavirus vaccine, reports Washington Post.
The regulators however held that the vaccine’s benefits continue to outweigh its risks.
EMA said it is reminding health-care professionals and people receiving the vaccine to “remain aware” of the possibility of very rare cases of blood clots combined with low levels of blood platelets occurring within two weeks of vaccination.
The Washington Post quoted EMA as stating that so far, most of the cases reported have occurred in women under 60 years of age, although it said it still has been unable to work out if particular groups were more at risk than others.
The agency urges authorities within the European Union to make their own decisions as to whether to use the data to restrict vaccine usage in certain parts of their populations.
The vaccine produced by AstraZeneca and Oxford University has been under intense scientific scrutiny since early last month, when a 49-year-old nurse died of complications due to blood clots following her vaccination in Austria. Other cases followed across Europe, leading some countries to suspend their use of the vaccine until scientific reviews were done.
Concerns center on a rare condition called cerebral venous sinus thrombosis, or CVST, a clot that stops blood from draining from the brain. Regulators have said it is occurring among those vaccinated at a rate above what they’d expect to see in the normal population.
Wednesday’s announcement is the latest blow for the vaccine that was touted as a key tool in leading the world out of the pandemic. Cheap and easier to store than others on the market, there are plans to roll it out in more than 140 countries through a program designed to ensure equitable distribution.
Cases of concern are small in number. Britain has documented the serious clots in about 1 in 500,000 shots. But higher rates in countries that began using AstraZeneca’s vaccine only among younger people have spurred debate as to whether the risks might be higher for certain age groups or for women. The EMA has estimated the risk to those under 60 to be about 1 in 100,000.
In Germany, 29 out of 31 patients with the brain clots have been women. But the European regulator has said that may be because countries like Germany began by vaccinating communities like health-care workers, which include more women.
Scientific teams in both Germany and Norway that have studied patients and blood samples have said the unusual clots are caused by an overactive immune response, and they can see no other likely trigger for that reaction in the patients other than the vaccine.
New guidelines for diagnosis by testing for the antibodies have already been circulated in countries including Germany and Britain.