Fall of 2023 was the first time a vaccine for respiratory syncytial virus became available for those most at risk, but now data shows the shots may have caused a few cases of Guillain-Barré syndrome, The New York Times reported March 1.
"At this point, due to the uncertainties and limitations, these early data cannot establish if there is an increased risk for GBS after vaccination in this age group," Thomas Shimabukuro, MD, the director of the CDC's Immunization Safety Office said during a Feb. 29 briefing.
The CDC's Vaccine Adverse Event Reporting system revealed 37 preliminary reports of adverse effects from RSV vaccines, 23 of which were verified by medical records. Pfizer's Abrysvo vaccine was linked to 15 of those reports and GSK's Arexvy vaccination was linked to eight, according to the Times.
Health officials acknowledged that while cases of Guillain-Barré syndrome caused by the vaccines are rare, ongoing surveillance and monitoring will be important to continue.
"I will say that these rates are higher than rates that we've observed for high-dose influenza and for Shingrix," Dr. Shimabukuro told the Times, adding that the data shows there were around three more cases of Guillain-Barré syndrome than anticipated per 1 million doses of Abrysvo.
"Due to the small number of GBS cases and size of the prelicensure studies, it is not known at this time whether these GBS cases or other neuroinflammatory events occurred due to random chance, or whether RSV vaccination might increase the risk of these events," a slide from the Feb. 29 meeting reads.
Overall, the benefits of vaccines still outweigh the adverse effects and risks, officials told The Times. For each 1 million doses of RSV vaccines given to adults over 65 years old, the vaccines help prevent an estimated 25,000 outpatient visits, 2,500 hospitalizations and around 130 deaths, the outlet reported in July.