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EU regulator says unusual blood clots should be listed as 'very rare side effect' of J&J vaccine

The European Medicines Agency said that the “overall benefits” of the vaccine in preventing Covid-19 outweigh the risks of side effects.

Image: DPA/PA Images

THE SAFETY COMMITTEE of the EU’s medicines regulator has concluded that unusual blood clots should be listed as “very rare side effects” of the Johnson & Johnson Covid-19 vaccine – but that the “overall benefits” of the vaccine in preventing Covid-19 outweigh the risks of side effects.

Ireland’s Health Products Regulatory Authority (HPRA) liaised with the EMA safety committee over this safety issue, and is to revise the Janssen Covid-19 vaccine product information to include this rare side effect.

In a statement released this afternoon, the European Medicines Agency (EMA) said that the cases it reviewed were very similar to the cases that occurred with the Oxford-AstraZeneca Covid-19 vaccine.

In a press briefing following the announcement, EMA executive director Emer Cooke said that there had been no cases in Europe, but that the vaccine had not been rolled out to the same extent in Europe as it had in the US.

“Early intervention of a specialist can change the outcome,” she said of the rare events, adding that it was important to know the signs of these unusual thrombosis events.

The EMA safety committee PRAC noted that the blood clots occurred mostly at unusual sites such as in veins in the brain (CVST) and the abdomen (splanchnic vein thrombosis) and in arteries, together with low levels of blood platelets and sometimes bleeding.

Cooke said vaccines play an “immensely important role” in combating Covid-19, stressing the toll the disease was having on people worldwide. 

Emer Cooke Emer Cooke. Source: EMA

Dr Sabine Straus, chair of PRAC, said that after liaising with the US regulator the FDA, and after analysing “all currently available evidence”, they have concluded that there is a possible link between these rare events and the J&J vaccine, which has had a limited rollout in Europe so far.

In response to the similarities between the rare blood clot events in the AstraZeneca vaccine and J&J vaccine, Dr Straus said: “There are quite some similarities between the two vaccines, but there are also differences”, citing the different vectors used by both vaccines and a different spike protein.

“It’s too early to conclude on that yet.”

Sabine Straus Dr Sabine Straus. Source: EMA

The EMA conclusion follows a number of cases of rare blood clots in the United States in people who had received the vaccine, similar to what was recorded with AstraZeneca in Europe.

Eight rare blood clot events with low levels of blood platelets were recorded among over 7 million doses of the J&J vaccine administered in the US. 

One of the events occurred in the clinical trials, Dr Straus said. These eight cases are the total rare blood clotting events reported with the J&J vaccine worldwide.

All cases occurred in people under 60 years of age (the median age of the eight cases was 33) within three weeks after vaccination, the EMA said – with the majority in women. Based on the currently available evidence, specific risk factors – such as sex or age – have not been confirmed, Dr Straus added.

She said that in one case, a woman affected was using the contraceptive pill, which in itself carries a risk factor in developing CVST.

“At the moment, we don’t know” whether these rare events are happening more or less frequently with the J&J vaccine than with the AstraZeneca vaccine, Dr Straus said.

People in Europe are very aware of the AstraZeneca vaccine, she said, adding that this might mean reporting “might be more aligned with occurrence”.

As for cases in the US, these rare blood clot events can occur up to three weeks after the vaccination. Since the US recommendation to pause the rollout of the J&J vaccine began on 13 April, the EMA is waiting to see if more cases are reported in this timeframe.

“There is still no way of telling whether it is occurring more frequently or less frequently than AstraZeneca at this moment in time,” Dr Straus said.

Cooke stressed that the review of the rare side effects linked to the Oxford-AstraZeneca vaccine is ongoing, and the EMA will provide an update on this before the end of this week.

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What this means for Ireland

This vaccine is a key component of Ireland’s vaccine rollout, with enough doses to fully vaccinate more than 600,000 people due to arrive this quarter. The plan had been to primarily target these vaccines for particular settings, such as those living in crowded accommodation.

Irish authorities have been waiting for the EMA decision on the one-shot J&J vaccine before they decided whether to increase the timeframe between administering the first and second dose of mRNA vaccines in Ireland.

Currently, the gap is four weeks for Pfizer and Moderna vaccines – but NPHET has been weighing up whether to increase this timeframe to eight or 12 weeks, to give the population a greater level of protection against Covid-19 quicker than under the four-week gap.

In the case of the AstraZeneca vaccine, after the EMA made a similar decision, Ireland’s vaccine expert group National Immunisation Advisory Committee (NIAC) decided out of an “abundance of caution” to limit the use of AstraZeneca to those aged over 60.

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