EMA stops short of imposing age restriction on AstraZeneca COVID vaccine despite thrombosis risk

A European Medicines Agency evaluation of blood clotting incidents linked to the AstraZeneca COVID-19 vaccine is unable to identify common risk factors but cases are predominantly in people under 60 and women

Several European countries have restricted the use of the AstraZeneca COVID-19 vaccine to elderly age groups
Several European countries have restricted the use of the AstraZeneca COVID-19 vaccine to elderly age groups

Cases of thrombosis from the AstraZeneca coronavirus vaccine have been predominantly reported in people under 60 and women, the European Medicines Agency said.

However, EMA has stopped short of issuing any guidelines or age restrictions since a study of 62 cases of vaccine-induced thrombosis across Europe has been unable to identify common risk factors.

Emer Cooke, EMA executive director, said the risk of thrombosis was a “very rare and unusual event” during a press conference after an evaluation by the agency's pharmacovigilance committee.

She said the AstraZeneca COVID-19 vaccine product literature should be updated to include thrombosis as a “possible side effect”.

“The evidence available on the incidences studied did not allow us to draw any causal link between gender and age groups,” she said.

EMA will be discussing on Wednesday evening with national competent authorities the outcome of the evaluations presented today.

Various national authorities have taken decisions to limit the use of the AstraZeneca vaccine in certain young age groups. Germany has recommended the AstraZeneca vaccine for those aged over 60.

The thrombosis link to age was probably the result of the manner in which the vaccine was being administered in different countries – in most cases the AstraZeneca vaccine was initially not given to elderly people.

Cooke said patients have to be aware of these risks but insisted the benefit of the vaccine in reducing the mortality from COVID-19 was much higher than the risk it posed.

Out of 39 million people vaccinated in Europe with AstraZeneca, there were 62 cases of cerebral thrombosis, 18 of which were fatal.

On Wednesday, Health Minister Chris Fearne said there have been no reported cases of thrombosis linked to the AstraZeneca vaccine in Malta.

Data given by EMA shows that there were 35 worldwide cases of thrombosis from the Pfizer vaccine and five cases from the Moderna. In Europe alone, 54 million doses of the Pfizer vaccine and four million doses of Moderna have been administered.

Sabine Straus, the chair of the pharmacovigilance committee, said a plausible explanation was an immune response to the vaccine leading to a condition similar to that seen in some patients treated with heparin.

However, she said further studies were being done to better understand the effect of the vaccine on thrombosis.
Peter Arlett, EMA’s head of data analytics, said the risk of thrombosis was similar to that of oral contraceptives, which can cause blood clots in some women.

Symptoms of thrombosis normally emerged some two weeks after the vaccine is administered.

EMA said patients must be made aware to look out for any signs of thrombosis side effects and report these immediately.