If certain anti-Covid vaccines increase the risk of developing Guillain-Barré syndrome, this is not the case with that of Pfizer, now almost exclusively used in France, according to a study relayed this Wednesday, October 11 by the French health authorities . “Messenger RNA vaccines do not increase the risk of Guillain-Barré syndrome, unlike adenoviral vector vaccines,” announced in a joint press release the National Medicines Safety Agency (ANSM) and Health Insurance.
Known to be rare, Guillain-Barré syndrome is a disease of the immune system that attacks peripheral nerves, causing pain, numbness, muscle weakness, or even difficulty walking. “In rare cases, the disease can cause serious neurological sequelae, respiratory failure and lead to death,” explains the ANSM.
A “more than doubled” risk for AstraZeneca
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 the approximately 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 at 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,” concludes the study. “This is reassuring in a context where messenger RNA serves as the basis for booster vaccination, immediately and in the future,” she adds.
However, if France now favors the Pfizer vaccine, other countries, particularly developing countries, continue to use adenovirus vaccines, in particular AstraZeneca.