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  4. FDA Requires Guillain-Barré Syndrome (GBS) Warning in the Prescribing Information for RSV Vaccines Abrysvo and Arexvy
  1. Safety & Availability (Biologics)

FDA Requires Guillain-Barré Syndrome (GBS) Warning in the Prescribing Information for RSV Vaccines Abrysvo and Arexvy

FDA Safety Communication

Purpose: To inform the public and healthcare providers that FDA has required and approved safety labeling changes to the Prescribing Information for Abrysvo (Respiratory Syncytial Virus Vaccine) manufactured by Pfizer Inc. and Arexvy (Respiratory Syncytial Virus Vaccine, Adjuvanted) manufactured by GlaxoSmithKline Biologicals. Respiratory Syncytial Virus (RSV) vaccine. The Prescribing Information for each vaccine has been revised to include the following language in the Warnings and Precautions section:

  • Abrysvo- The results of a postmarketing observational study suggest an increased risk of Guillain-Barré syndrome (GBS) during the 42 days following vaccination with Abrysvo.
  • Arexvy- The results of a postmarketing observational study suggest an increased risk of Guillain-Barré syndrome during the 42 days following vaccination with Arexvy.

GBS is a rare disorder in which the body’s immune system damages nerve cells, causing muscle weakness and sometimes paralysis.

New Warning about Risk for GBS Following Vaccination

FDA conducted a postmarketing observational study that assessed the risk of GBS following vaccination with Abrysvo and Arexvy. Based on FDA’s evaluation of data from clinical trials, reports to the Vaccine Adverse Event Reporting System (VAERS), and the postmarketing study, FDA has determined that the overall body of evidence suggests increased risks of GBS with Abrysvo and Arexvy, but that available evidence is insufficient to establish a causal relationship.

About the Study that Assessed the Risk of GBS Following Vaccination

The association between vaccination with Abrysvo and Arexvy and GBS was evaluated among Medicare beneficiaries 65 years of age and older. Using Medicare claims data, between May 2023 through July 2024, vaccinations with Abrysvo and Arexvy were identified through Current Procedural Terminology (CPT)/Healthcare Common Procedure Coding System (HCPCS) codes and National Drug Codes, and potential cases of hospitalized GBS among recipients of Abrysvo and Arexvy were identified through International Classification of Diseases (ICD) codes. GBS diagnoses in claims data were confirmed by medical record review when available.

The risks of GBS following vaccination with Abrysvo and Arexvy were assessed in self-controlled case series analyses using risk windows of 1 to 42 days post vaccination and control windows of 43 to 90 days post vaccination. The analyses of all GBS cases based on claims data suggest an increased risk of GBS during the 42 days following vaccination, with an estimated 9 excess cases of GBS per million doses of Abrysvo, and an estimated 7 excess cases of GBS per million doses of Arexvy administered to individuals 65 years of age and older. Background risks of GBS in study populations influence excess GBS case estimates and may differ between studies and analyses within a study, precluding direct comparisons of excess GBS case estimates from other vaccine studies or populations.

While the results from the self-controlled case series analyses of this observational study suggest increased risks of GBS with Abrysvo and Arexvy, available evidence is insufficient to establish a causal relationship.

About Abrysvo

Abrysvo was initially approved on May 31, 2023, for the prevention of lower respiratory tract disease (LRTD) caused by respiratory syncytial virus (RSV) in individuals 60 years of age and older. Subsequently, FDA has approved the vaccine for the following:

  • prevention of LRTD caused by RSV in individuals 18 through 59 years of age who are at increased risk for LRTD caused by RSV;
  • 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 6 months of age.

As part of FDA’s review to support the approval of Abrysvo, FDA evaluated safety data from clinical trials in which approximately 22,000 individuals received Abrysvo and approximately 22,000 individuals received placebo. Among study participants 60 years of age and older, one participant developed GBS 7 days following vaccination and one participant developed Miller-Fisher syndrome (a variant of GBS) 8 days following vaccination. The initial approval included a requirement by FDA for the manufacturer to conduct a study to evaluate the risk of GBS among approximately 1.5 million older adults vaccinated with Abrysvo in the United States. The approval of Abrysvo in individuals 18 through 59 years of age who are at increased risk for LRTD caused by RSV included a requirement by FDA for the manufacturer to conduct a study to evaluate GBS in this population. FDA has also required the manufacturer to conduct a study to assess the serious risk of GBS following administration of Abrysvo in pregnant individuals.

About Arexvy

Arexvy was initially approved on May 3, 2023, for the prevention of LRTD caused by RSV in individuals 60 years of age and older. Subsequently, FDA has approved the vaccine for use in individuals 50 through 59 years of age who are at increased risk for LRTD caused by RSV.

As part of FDA’s review to support the approval of Arexvy, FDA evaluated safety data from clinical trials in which approximately 16,000 individuals received Arexvy and approximately 13,000 individuals received placebo. One participant developed GBS nine days after receiving Arexvy. FDA has required the manufacturer to conduct a study to evaluate the risk of GBS among 1.9 million adults 50 years of age and older vaccinated with Arexvy in the United States.

FDA’s Determination of the Safety and Effectiveness of the Vaccines

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 Abrysvo and Arexvy.

FDA has further determined that the benefits of vaccination with Abrysvo and Arexvy continue to outweigh their risks.

Continuous monitoring and assessment of the safety of all vaccines remain an FDA priority and we are committed to informing the public when we learn new information about these vaccines.

How to Report a Suspected Adverse Event After Vaccination

Suspected adverse events may be reported to (VAERS), which is co-managed by the FDA and the Centers for Disease Control and Prevention (CDC).

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