Risk of Guillain-Barré Syndrome After RSV Vaccination
Current evidence does not provide clear, conclusive proof of an elevated risk for Guillain-Barré Syndrome (GBS) associated with RSV vaccination in older adults, but a potential risk cannot be ruled out. 1
Current Risk Assessment
According to the most recent 2024 Advisory Committee on Immunization Practices (ACIP) guidelines, postlicensure safety data from an FDA self-controlled case series analysis among Medicare beneficiaries aged ≥65 years showed:
- For GSK's Arexvy: GBS adjusted incidence rate ratio of 2.30 (95% CI = 0.39–13.72) 1
- For Pfizer's Abrysvo: GBS adjusted incidence rate ratio of 4.48 (95% CI = 0.88–22.90) 1
These findings suggest a possible increased risk, but the confidence intervals cross 1.0, indicating statistical uncertainty.
Risk Quantification
More specific risk estimates from post-marketing surveillance data (May 2023 to April 2024) indicate:
- Arexvy (RSVPreF3): Approximately 1.8 reports of GBS per million doses 1
- Abrysvo (RSVpreF): Approximately 4.4 reports of GBS per million doses 1
These rates appear higher than expected background rates in the general population.
Clinical Observations
Across clinical trials:
- RSVPreF3 (Arexvy): 3 inflammatory neurologic events reported in 17,922 participants within 42 days post-vaccination, including 1 case of GBS 1
- RSVpreF (Abrysvo): 3 inflammatory neurologic events reported in 20,255 participants within 42 days post-vaccination, including 1 case of GBS and 1 case of Miller Fisher syndrome (a GBS variant) 1
- mRNA RSV vaccine (mResvia): No cases of GBS or other inflammatory neurologic events were recorded within 42 days after vaccination 1
Risk-Benefit Analysis
Despite the potential GBS risk, the ACIP has determined that the benefits of RSV vaccination outweigh the risks. A modeling study estimated that per 1 million RSV vaccine doses administered over two consecutive RSV seasons:
- Prevented outcomes: 3,817-4,283 RSV-associated hospitalizations, 561-630 ICU admissions, and 539-605 deaths 1, 2
- Potential risk: Approximately 3-16 cases of GBS per million doses 1
Important Considerations for Clinicians
- Timing of risk: Most vaccine-associated GBS cases occur within 42 days of vaccination, with the highest risk in the first 21 days 3, 4
- Patient history: A history of GBS is not an absolute contraindication to RSV vaccination, as recurrence risk appears low 5
- Monitoring: Patients should be informed about early symptoms of GBS (progressive weakness, numbness/tingling in extremities, difficulty walking)
- Vaccine selection: Consider that different RSV vaccines may have different risk profiles for GBS 1
Special Populations
The ACIP recommends a single dose of any FDA-approved RSV vaccine for:
- All adults aged ≥75 years
- Adults aged 60–74 years who are at increased risk for severe RSV disease (chronic medical conditions, moderate/severe immune compromise, nursing home residents) 1
Clinical Vigilance
Healthcare providers should:
- Be aware that GBS surveillance is ongoing, with additional analyses underway 1
- Report any suspected cases of GBS following vaccination to appropriate surveillance systems
- Recognize that the risk-benefit assessment strongly favors vaccination, particularly in high-risk groups 1, 2
While the potential risk of GBS exists, it remains rare, and the benefits of RSV vaccination in preventing severe RSV disease, hospitalization, and death substantially outweigh this potential risk for recommended populations.