Unusual blood clots should be listed as “very rare” side effects of the Oxford-AstraZeneca Covid-19 vaccine, Europe’s premier drug agency said on Wednesday.
Emer Cooke, the executive director of the European Medicines Agency, said that “the overall benefits of AstraZeneca outweigh the risks of side effects”.
The vaccine was “shown to be highly effective,” she said at a press conference, adding that it “prevents and saves lives from serious illness and hospitalization.”
Cooke added, however, that after a “very thorough analysis” the regulator concluded that reported cases of unusual blood clotting following vaccination with the AstraZeneca vaccine should be listed as possible side effects of the vaccine.
Due to very low numbers of blood clots in younger people reported in the UK, the Joint Vaccination and Immunization Committee, the UK’s vaccine advisory body, said on Wednesday it was recommending an alternative Covid-19 vaccine to those under 30 Oxford-AstraZeneca vaccine, if one is available.
More than 20 million doses of the Oxford-AstraZeneca vaccine have been administered in the UK to date, according to the separate Medicines and Health Products Regulatory Authority (MHRA).
In a separate statement, the EMA said blood clots should be listed “as a very rare side effect of Vaxzevria,” the official name of the AstraZeneca vaccine.
“So far, most reported cases in women under 60 have occurred within two weeks of being vaccinated,” the statement added. “Based on currently available data, specific risk factors have not been confirmed.”
The announcement comes less than a month after the EMA said the Oxford-AstraZeneca vaccine was “safe and effective”. This statement was prompted after a number of countries including Germany, France and Italy suspended the AstraZeneca vaccine because of concerns about blood clots in some recipients.
Most European countries that had postponed the vaccine resumed administration after European regulators said it was safe. However, according to The Associated Press, Danish officials said last month they would extend the vaccine suspension while they continue to investigate a possible link to blood clots.
In the UK, which has dispensed more doses of the AstraZeneca vaccine than any other country, the Medicines Agency also reported Wednesday that 79 people in the UK had suffered from rare blood clots and 19 of them died following vaccination.
June Raine, the executive director of MHRA, said the agency’s review revealed that more work is needed to determine beyond any doubt that the vaccine caused the side effects.
In any case, the rare suspected side effects occurred in an “extremely” small number of people, she added.
Raine said, based on current evidence, the benefits of the AstraZeneca Covid-19 vaccine against the disease and the associated risks of hospitalization and death continue to outweigh the risks for the vast majority of cases.
She said the risk of these types of rare blood clots is about 4 in a million people who receive the vaccine.
Meanwhile, Dr. Sabine Straus, Chair of the EMA’s Pharmacovigilance Risk Assessment Committee, told Wednesday that the data currently available “did not allow us to identify a clear cause of these complications”.
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She added that “no specific risk factors have been identified on the basis of the current data” and therefore the Committee “cannot recommend any specific risk reduction measures”.
“Most of the cases have occurred in people under the age of 60 and in women,” she said. “However, because of the different ways the vaccine is used in different countries, the committee did not conclude that age and gender are factors.”
More research would be done, she said.
Cooke added that the data available did not allow the EMA to establish a causal relationship with age groups or with men or women. “There is much more use in younger age groups in the UK than in the European Union and we will take this into account in our further assessments,” she said.
Also on Wednesday, South Korea announced that it would temporarily cease making AstraZeneca’s vaccine available to anyone under 60 as part of the European review. It also cleared the Johnson & Johnson shot to expedite the introduction of vaccination.