FDA Mandates Updates to Prescribing Information for RSV Vaccines Abrysvo, Arexvy for Increased Guillain-Barré Syndrome Risk

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The FDA announced that it has mandated updates to the prescribing information for respiratory syncytial virus (RSV) vaccines Abrysvo (Pfizer) and Arexvy (GSK) to include a warning about a potential increased risk of Guillain-Barré Syndrome (GBS). According to the company, the decision follows a postmarketing observational study that evaluated Medicare data from May 2023 to July 2024, showing nine and seven cases of GBS per million doses for Abrysvo and Arexvy, respectively, within 42 days of vaccination.

However, the FDA stated that these findings don’t necessarily establish a definitive causal relationship. The regulatory body conducted a postmarketing observational study that assessed the risk of GBS following vaccination with either vaccine. An analysis of data from clinical trials, reports to the Vaccine Adverse Event Reporting System (VAERS), and the postmarketing study led the FDA to conclude that more evidence is needed to determine the connection between the vaccines and GBS.

The FDA evaluated the association between the vaccines and cases of GBS in Medicare beneficiaries over 65 years of age by using Medicare claims between May 2023 and July 2024 to identify vaccinations with Abrysvo and Arexvy via Current Procedural Terminology/Healthcare Common Procedure Coding System codes and National Drug Codes. Potential cases of hospitalized GBS among recipients of Abrysvo and Arexvy were identified through International Classification of Diseases codes.¹

According to the Centers for Disease Control and Prevention, it is estimated that around 3,000 to 6,000 people develop GBS each year in the United States. While anyone can develop it, GSB is more common in men and in people over 50 years of age.²

According to the National Organization for Rare Disorders, GBS affects about one to two people out of every 100,000 individuals each year, while the exact cause is unknown. Around half of all cases include a gastrointestinal or respiratory infection a few days before onset. In most cases, people recover completely or nearly completely. However, some have mild residual effects such as foot drop or abnormal feeling in the feet and hands for two or more years. Less than 15% of patients have substantial long-term disability severe enough to need a cane, walker, or wheelchair. In 5% of patients, death can occur and is less common in countries with intensive care facilities.³

The FDA first approved Abrysvo on May 31, 2023, for the prevention of lower respiratory tract disease (LRTD) caused by RSV in patients over 60 years of age. Since then, the regulatory body has also approved it for the prevention of LRTD caused by RSV in individuals 18 through 59 years of age with an increased risk of LRTD and immunization of pregnant individuals at 32 through 36 weeks gestational age for the prevention of LRTD and severe LRTD caused by RSV in infants from birth through six months of age.

Arexvy was first approved on May 3, 2023, for the prevention of LRTD caused by RSV in individuals 60 years of age and older. Since then, it has also been approved to treat individuals 50 through 59 years of age with an increased risk for LRTD caused by RSV.

Moving forward, the FDA has required and approved safety labeling changes to the prescribing information for Abrysvo and Arexvy based on the totality of data from clinical trials, reports to VAERS, and the results of self-controlled case series analyses in an observational study conducted by FDA that suggest increased risks of GBS with either vaccination.¹

References

1. FDA Requires Guillain-Barré Syndrome (GBS) Warning in the Prescribing Information for RSV Vaccines Abrysvo and Arexvy. FDA. Accessed January 9, 2025. https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/fda-requires-guillain-barre-syndrome-gbs-warning-prescribing-information-rsv-vaccines-abrysvo-and?utm_medium=email&utm_source=govdelivery

2. Guillain-Barré Syndrome. CDC. Accessed January 9, 2025. https://www.cdc.gov/campylobacter/signs-symptoms/guillain-barre-syndrome.html#:~:text=Number%20of%20people%20affected,of%20Campylobacter%20infections%20develops%20GBS.

3. Guillain-Barré Syndrome. NORD. May 6, 2024. Accessed January 9, 2025. https://rarediseases.org/rare-diseases/guillain-barre-syndrome/