There is a “possible link” between Johnson & Johnson’s Covid-19 vaccine and very rare blood clots, the European medicines regulator has said.
The European Medicines Agency (EMA) said that a warning should be added to the product information for the Janssen jab.
However, it said that the "overall benefits of Covid-19 Vaccine Janssen in preventing Covid-19 outweigh the risks of side effects".
The EMA said in a statement on Tuesday that it found a "possible link to very rare cases of unusual blood clots with low blood platelets" with the vaccine.
The Pharmacovigilance Risk Assessment Committee (PRAC) – the regulator's safety committee – said that these events should be listed as very rare side effects of the vaccine.
The safety committee “concluded that a warning about unusual blood clots with low blood platelets should be added to the product information for Covid-19 Vaccine Janssen.”
Ursula von der Leyen, President of the European Commission, welcomed the decision and described it as good news for the roll-out of vaccination campaigns across the EU.
A statement revealed that the safety committee “took into consideration all currently available evidence including eight reports from the United States of serious cases of unusual blood clots associated with low levels of blood platelets, one of which had a fatal outcome.”
The Health Products Regulatory Authority (HPRA) says it is engaging with the National Immunisation Advisory Committee (Niac) and the Department of Health on the matter and will continue to participate in the EMA’s coordinated safety monitoring of Covid-19 vaccines.
In a statement the HPRA said vaccinated with the "The overall benefit of vaccination in preventing Covid-19 disease outweighs the risks of known side effects."
More than seven million people had received the J&J vaccine in the US.
The EMA said that all cases occurred in people between the ages of 18 and 49 and occurredwithin three weeks after vaccination, the majority in women.
"Based on the currently available evidence, specific risk factors have not been confirmed," a statement added.
The EMA said that the blood clots occurred mostly “at unusual sites such as in veins in the brain (cerebral venous sinus thrombosis, CVST) and the abdomen (splanchnic vein thrombosis) and in arteries, together with low levels of blood platelets and sometimes bleeding”.
Dr Sabine Straus, the PRAC Chair, said today at a press briefing that "at this moment it is not possible to identify clear risk factors such as gender or age.”
Dr Strauss said that in one of the cases, a woman was using a contraceptive pill, which she said carries a risk of CVST.
The EMA said that people taking the jab and health workers should be made aware of the potential very rare side effect, adding that prompt specialist medical treatment can help aid recovery and avoid complications.
Dr Straus said that symptoms to look out for included shortness of breath, chest pain, swelling in the legs, persistent abdominal pain and skin bruising beyond the site of injection.
She said people should also look out for neurological symptoms including severe or persistent headache and blurred vision.
“Those are the most telling symptoms that we have been able to identify based on the careful review of the cases,” she said.
Emer Cooke, the EMA’s executive director, said that it was important to make sure that people have the “facts and information” to take action if they get any of the "very rare" side effects of the vaccine.
The EMA said in a statement that "one plausible explanation for the combination of blood clots and low blood platelets is an immune response, leading to a condition similar to one seen sometimes in patients treated with heparin called heparin induced thrombocytopenia, HIT."
They said these cases were “were very similar to the cases that occurred with the Covid-19 vaccine developed by AstraZeneca”.
Ms Cooke said there has been no cases of blood clots in Europe with the J&J jab and that it has asked Janssen to carry out additional studies.
"When vaccines are rolled-out to large numbers of people, very rare events can occur that were not identified in the clinical trials," said Ms Cooke.
The EMA said that it will continue to monitor the vaccine’s safety and effectiveness and provide the public with the latest information.
Around 600,000 doses of the vaccines are due for delivery to Ireland between April and June this year.
The EMA originally approved the J&J vaccine for use in Europe last March.
The company said earlier this month that it is delaying the rollout of its coronavirus vaccine in Europe amid a US probe into reports of rare blood clots in some recipients.
“We have been reviewing these cases with European health authorities,” Johnson & Johnson said.
“We have made the decision to proactively delay the rollout of our vaccine in Europe.”
US regulators recommended a pause to give time to investigate reports of a rare blood-clotting side effect.
The move was made out of an “abundance of caution”, the US Food and Drugs Administration and the Centres for Disease Control and Prevention said in a joint statement.