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Possible link between Astrazeneca vaccine and blood clots, says EU health regulator

European Medicines Authority executive director Emer Cooke. (Source: Keystone).

The European Medicines Agency (EMA) on Wednesday said blood clots should be listed as a “very rare” effect of the Oxford-AstraZeneca Covid vaccine, but emphasised the benefits far outweighs the risks.

Following an investigation looking at the 86 cases of blood clots in the EU, the European Medicines Agency (EMA) concluded that unusual blood clots with low blood platelets should be listed as very rare side effects of the AstraZeneca vaccine.

So far, most of the cases reported have occurred in women under 60 years of age within two weeks of vaccination. Based on the currently available evidence, specific risk factors have not been confirmed, the EMA said in a statement.

In a televised press conference the EMA executive director Emer Cooke added that “a plausible explanation for these rare side events is an immune response to the vaccine similar to one seen in patients treated with heparin.”

During the same press conference Dr Sabine Straus, in charge of the EMA’s safety committee said possible symptoms of the vaccine could include “ for example shortness of breath, chest pain, swelling in the leg, persistent abdominal pain, neurological symptoms including severe or persistent headache or blurred vision and skin bruising beyond the site of injection,” adding that these side effects will be listed as possible adverse drug reaction on the vaccines product information.

As a result of this the medicine’s regulator said it is of “great importance” that all those receiving the shot and health care professionals are aware of the risks, whilst also looking out for potential symptoms which usually show up two weeks following the injection.

After “intensive discussions” based on scientific evidence, Cooke maintained that the vaccine should be used as “Covid-19 is a very serious disease with high hospitalisation and death rates, ” and that “this vaccine has proved to be highly effective and it is saving lives.”

EMA said it had received reports of 169 cases of rare brain blood clots in people who had the AstraZeneca dose, compared to the 34 million shots administered in the European Economic Area.

Joining the EMA and other health regulators, the WHO's director for regulation and pre-qualification, Rogerio Pinto de Sa Gaspar said “there is no link for the moment between the vaccine and thrombotic events with thrombocytopenia,” repeating once again that the vaccine is safe for use.

On Wednesday, the World Health Organization ’Global Advisory Committee on Vaccine Safety, released an interim statement explaining that the current evidence points towards a causal relationship between the vaccine and blood clots, although this is not yet confirmed. As such “specialised studies are needed to fully understand the potential relationship between vaccination and possible risk factors.”

Read also: More countries suspend Oxford-AstraZeneca vaccine as health experts urge continued use

In recent weeks AstraZeneca shot has been dodged by several European countries over safety concerns, briefly suspending the use of the vaccine last month. Most restated have now resumed the rollout of the vaccine, although many with age restrictions, including the UK’s own medicines regulator which on Wednesday said the vaccine should now only be given to over 30s.

France, Germany and Italy have all restarted using the AstraZeneca shots again, and in the case of Germany and France they have applied special guidelines limiting the age it should be used for, with France not currently administering to under 55s or over 75s.

The EMA and WHO stresses the continued use of the potentially lifesaving vaccine, as the ”large benefits outweigh the risks of side effects.”