Guillain-Barré syndrome: a risk with certain anti-Covid vaccines, except with those with messenger RNA

Certain anti-Covid vaccines increase the risk of developing Guillain-Barré syndrome, but not that of Pfizer, now almost exclusively used in France, according to a study relayed Wednesday October 11 by the French health authorities. “Messenger RNA vaccines do not increase the risk of Guillain-Barré syndrome, unlike adenoviral vector vaccines,” the National Medicines Safety Agency (ANSM) and Insurance announced in a joint press release. disease.

Under their aegis, researchers carried out a study published at the beginning of October in the journal Neurology and which attests that vaccination by messenger RNA – which includes the Moderna and Pfizer vaccines – is not associated with a risk of Guillain-Barré syndrome.

“Guillain-Barré syndrome is a rare disease in which the immune system attacks peripheral nerves, which can lead to pain, numbness, muscle weakness, or difficulty walking,” the agencies remind. “In rare cases, the disease can cause serious neurological sequelae, respiratory failure and lead to death.” Isolated cases of this syndrome had been associated with having been vaccinated with AstraZeneca and Janssen vaccines, known as adenovirus vaccines and used for a time in French vaccination campaigns before being abandoned in favor of those with messenger RNA, i.e. Moderna and Pfizer.

The study relayed on Wednesday sought to assess this risk by retrospectively comparing the vaccination situation of some 2,000 people hospitalized for this syndrome between the end of 2020 and the beginning of 2022. It emerges that vaccination by AstraZeneca and Janssen is indeed associated with a more than doubled risk of developing Guillain-Barré syndrome. However, researchers point out that this risk is significantly higher in the event of coronavirus infection.

On the other hand, “there was no statistically significant increase in the risk of Guillain-Barré syndrome after the administration of messenger RNA vaccines,” the study concludes. “This is reassuring in a context where messenger RNA serves as the basis for booster vaccination, immediately and in the future,” she adds. In France, in particular, it is the Pfizer vaccine which is used almost exclusively in the campaign launched this fall by the health authorities. Other countries, particularly developing countries, however, continue to widely use adenovirus vaccines, in particular AstraZeneca.