Monday 08 August 2022

Blood clots, low platelet count are possible Janssen vaccine side effects, EMA says

The European Medicines Agency has brought hundreds of new jobs. Photo: Odi Busman

The Amsterdam-based European Medicines Agency has acknowledged that thrombosis and a lower number of blood platelets may be a very rare side effect of the Janssen coronavirus vaccine and say they should be mentioned in the official product information.

However, the EMA said at a news conference on Tuesday, the advantages offered by the vaccine, which is single dose, outweigh the disadvantages. ‘The benefits of the vaccine continue to outweigh the risks for people who receive it,’ the EMA said. ‘The vaccine is effective at preventing COVID-19 and reducing hospitalisations and deaths.’

The agency examined eight cases of blood clots in the US, one of which was fatal. In total, some seven million people have been given the Janssen vaccine.

All cases occurred in people under 60 years of age within three weeks after vaccination, the majority in women. Based on the currently available evidence, specific risk factors have not been confirmed, the EMA said. ‘The cases reviewed were very similar to the cases that occurred with the COVID-19 vaccine developed by AstraZeneca, Vaxzevria.’

As yet the health ministry has not commented on the findings. ‘It is now up to health minister Hugo de Jonge to decide what the consequences of this are for the Dutch vaccination campaign’ Ton de Boer, chairman of the Dutch medicines agency CBG, told broadcaster NOS.

Johnson & Johnson halted deliveries of the Leiden-developed vaccine to Europe pending the EMA’s verdict and De Jonge stopped its use in the Netherlands temporarily.

The Netherlands has also stopped using the AstraZeneca vaccine on the under-60s because of the possible risk. This decision went against the EMA’s recommendations and has also been widely criticized in the Netherlands

The Janssen vaccine is the fourth to be approved by the EMA and is supposed to form the backbone of the Dutch vaccination programme. De Jonge has ordered 11.3 million doses.

Currently around 100,000 people a day are being vaccinated in the Netherlands, taking the total shots placed to 4.6 million

Thank you for donating to

The team would like to thank all the generous readers who have made a donation in recent weeks. Your financial support has helped us to expand our coverage of the coronavirus crisis into the evenings and weekends and make sure you are kept up to date with the latest developments. has been free for 14 years, but without the financial backing of our readers, we would not be able to provide you with fair and accurate news and features about all things Dutch. Your contributions make this possible.

If you have not yet made a donation, but would like to, you can do so via Ideal, credit card or Paypal.