US pharmaceuticals group Johnson & Johnson is halting the roll-out of its Leiden-developed vaccine to Europe because of possible thrombosis-related side effects.

The decision was taken after officials in the US started an investigation into six cases in which young women developed a rare form of thrombosis after being vaccinated. So far 6.8 million people in the US have had the jab.

‘We are aware of an extremely rare disorder involving people with blood clots in combination with low platelets in a small number of individuals who have received our COVID-19 vaccine,’ the company said.

‘In addition, we have been reviewing these cases with European health authorities. We have made the decision to proactively to delay the rollout of our vaccine in Europe,’ the statement said. ‘We have been working closely with medical experts and health authorities, and we strongly support the open communication of this information to healthcare professionals and the public.’

The Netherlands received its first delivery of 79,000 doses of the vaccine on Monday which has been earmarked for front line healthcare workers, and was due to receive a further shipment of 90,000 doses next week. In total, the Netherlands has three million Janssen doses on order up to June 3.

As yet it is unclear what the impact of the decision to halt distribution will be on the Dutch vaccination strategy.

The Dutch medical assessment agency CBG said that the advantages attached to using the single-dose jab currently outweigh any risks.  If the European research indicates action should be taken, such as changing the product information, then we will inform everyone involved, the CBG said in a statement.

AstraZeneca

The Netherlands has already stopped using the AstraZeneca vaccine on the under 60s because of the risk of developing rare types of blood clots. Thrombosis-related complaints have  been reported in connection with the Pfizer and Moderna vaccines as well.

Immunology professor Marjolein van Egmond told NOS at the weekend that rare side effects were only to be expected, adding that some Covid-19 patients have also developed thrombosis.

‘You can never eliminate all risks,’ she said. ‘You have to make sure that you weigh up the advantages against the disadvantages. And in this case, the risk is very small.’

According to the Dutch thrombosis foundation, 11 people in the Netherlands are diagnosed with the disease every hour and 40 people a day die as a result.