Blood Clots & AstraZeneca: Regulator Confirms Vaccine Link

Further complicating Europe’s struggles to vaccinate its populations, the EU Medicines Agency has linked the AstraZeneca vaccine to very rare blood clots but said vaccination benefits still outweigh the risks.

B cells release antibodies to bind to the virus that creates Covid-19. (Image courtesy of AstraZeneca via Courthouse News)

(CN) — Insisting that the risk is one far outweighed by the benefits of Covid-19 vaccination, European regulators determined Wednesday that the Oxford-AstraZeneca coronavirus vaccine likely causes a small number of people to develop potentially deadly blood clots.

The European Medicines Agency’s warning about the blood clot risk further complicates Europe’s efforts to vaccinate its populations and gain control of a pandemic killing about 2,000 people a day in the European Union. The EU has fallen behind the United States and the United Kingdom in its vaccination drive, leaving it vulnerable to the virus and exacerbating the economic damage by prolonging lockdowns and restrictions.

“It’s very important that we use the vaccines that we have available to us, we need to beat this pandemic,” Emer Cooke, the agency’s executive director, said during a news briefing on Wednesday. “These are very rare side effects.”

Dr. Sabine Straus, the head of a panel of experts investigating the blood clots, said there was a “strong association” that the vaccine caused blood clots in a few people who received the AstraZeneca shot. Nonetheless, she said the vaccine is safe and effective and that side effects were to be expected in such a mass vaccination drive.

The panel of experts examined 86 cases of blood clots, which led to 18 deaths among 25 million people who received the vaccine by March 22 in the U.K. and the EU. Straus said 169 reports of blood clots were reported as of April 4 in the EU and U.K., where about 34 million AstraZeneca vaccinations have been administered.

Scientists believe the vaccine may kick start an immune response that can lead to blood clots with low blood platelets in venous sinuses that drain blood from the brain and in the veins of a person’s body. The EMA said a warning about the possible blood clot risk needs to be added to the vaccine.

The EMA said it couldn’t determine whether certain groups of people may be at more risk, though the majority of blood clots occurred in women under the age of 60 receiving the AstraZeneca shot.

Regulators in the EU and the U.K. were taking steps to adjust their recommendations. Britain’s Medicines and Healthcare Products Regulatory Agency also found a possible link with blood clots on Wednesday.

British authorities said people under the age of 30 will be offered a choice other than the AstraZeneca vaccine. Belgium said it will restrict the vaccine for those over 55. Other countries were likely to follow suit. EU health ministers met Wednesday to discuss their options.

This still from promotional video shows the assembly line at a plant manufacturing a vaccine against the coronavirus that causes Covid-19. (Image courtesy of AstraZeneca via Courthouse News)

For weeks, Europeans have been given conflicting information about the vaccine, with some countries opting to administer it only to older people. In March, as the blood clot risk emerged, several European countries suspended its use altogether.

The suspensions in Europe were lifted after the EMA declared the vaccine safe and effective on March 18, though at the time the agency said it could not rule out a link to blood clots.

Making the vaccine even more problematic, the EU accused AstraZeneca, a British-Swedish pharmaceutical company, of breaking its contract with the EU by favoring the U.K. and falling short of its promised deliveries.

The EMA’s new findings will cast new doubts on the vaccine, especially for younger people who are at much lesser risk from the coronavirus. Many Europeans, particularly in France, have expressed wariness over vaccines.

AstraZeneca developed the vaccine with scientists at the University of Oxford and support from the U.K. government. The manufacturers pledged to not profit from its sale, making it an early favorite candidate in the race to develop vaccines. The antidote uses a common vaccine technique that takes a bioengineered version of a harmless common-cold virus found in chimpanzees to tell human cells to make antigens.

Close up of adenovirus vector. (Image courtesy of AstraZeneca via Courthouse News)

The low-cost vaccine, which AstraZeneca renamed Vaxzevria after it was linked to possible blood clots, is central to the World Health Organization’s global vaccination drive. The United Nations health agency says the blood clot risk has not been confirmed and that the vaccine’s benefits far outweigh its possible risks.

“It is important to note that whilst concerning, the events under assessment are very rare, with low numbers reported among the almost 200 million individuals who have received the AstraZeneca Covid-19 vaccine around the world,” the WHO said in a statement.

For its part, AstraZeneca has said there is no evidence the vaccine increases the risk of blood clots. On Wednesday, the company said it was working with regulators to add the risk of blood clots to its product information. The EMA said it asked the company to do additional safety studies.

The EMA said it was evaluating whether Johnson & Johnson, another vaccine based on a similar method to the AstraZeneca product, may also carry a blood clot risk. Of about 4.5 million so far vaccinated with the Johnson & Johnson vaccine around the world, it said three cases of blood clots have been reported.

The EU’s doubts about the AstraZeneca vaccine drew a lot of criticism from both within the bloc and outside, with many commentators blasting EU bureaucrats and politicians as unnecessarily fomenting suspicions about the vaccine. Unlike the United States and the U.K., the EU chose not to approve vaccines on an emergency basis.

“The AstraZeneca experience shows that our pharmacovigilance system works,” Stella Kyriakides, the EU’s health commissioner, said Wednesday on Twitter. “But it is essential that we follow a coordinated approach across the EU.”


Courthouse News reporter Cain Burdeau is based in the European Union.

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