Vaccine ‘linked’ to clots
EUROPEAN and British medicine regulators said yesterday they had found possible links between AstraZeneca’s coronavirus vaccine and reports of very rare cases of brain blood clots, in a setback for inoculation campaigns.
A British government advisory group said the vaccine should not be given to the under-30s where possible, though an official said this was “really out of the utmost caution, rather than because we have any serious safety concerns”.
More than a dozen countries have suspended use of the vaccine, which has been given to tens of millions of people in Europe, after reports linking it to blood clotting in a few dozen recipients.
The European Medicines Agency (EMA) said it was “reminding healthcare 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”.
“So far, most of the cases reported have occurred in women under 60 years of age within two weeks of vaccination,” it added. “Based on the currently available evidence, specific risk factors have not been confirmed.”
The EMA received reports of 169 cases of the rare brain blood clot by early April, after 34 million doses had been administered in the European Economic Area, according to Sabine Straus, chair of the EMA’s safety committee. In comparison, four women out of 10 000 would get a blood clot from taking oral contraception.
“We know that we are rolling out vaccines on a very large scale. We will see events occurring … Some of them by chance,” Straus said.
EU health ministers were told in a letter from the EMA that the announcement on the safety of the vaccine would have immediate implications for vaccination plans and require a co-ordinated response.
The chief executive of Britain’s health regulator, June Raine, said the benefits of the vaccine outweighed the risks for the vast majority of people. She said those risks were more finely balanced for younger people – for whom the risks from coronavirus infection are, on average, lower.
Wei Shen Lim, Covid-19 chairperson for Britain’s advisory Joint Committee on Vaccines and Immunisation, said it was preferable for adults under 30 with no underlying health conditions to be offered another vaccine.
The letter to the EU health ministers was sent by the Portuguese presidency of the EU on Tuesday to invite them to an extraordinary virtual meeting yesterday, to be held immediately after the decision by the EU drugs regulator.
The AstraZeneca vaccine is sold at cost, and is by far the cheapest and most high-volume launched so far, and has none of the extreme refrigeration requirements of some other vaccines.
After extensive use in Britain and mainland Europe, it is set to be the mainstay of vaccination programmes in much of the developing world.
Experts say that, even if a causal link between the vaccine and blood clots is proved, the risks to the general population of getting a serious clot are vanishingly small compared to the risks from possible Covid-19 infection, which can also cause similar clots, or from many other widely used drugs such as the birth control pill.
“The risk of mortality from Covid is much greater than the risk of mortality from these rare side-effects,” EMA’s executive director Emer Cooke said yesterday.
AstraZeneca has said previously its studies have found no higher risk of blood clots in those vaccinated than in the general population.
Scientists are exploring several possibilities that might explain the rare brain blood clots. One theory suggests the vaccine triggers an unusual antibody in some rare cases; other investigators are looking into a possible link with birth control pills.
While many countries have resumed using the shot, some have imposed age restrictions, with younger women perceived to be more vulnerable.