Evaluation of Guillain-Barre syndrome following Respiratory Syncytial Virus Vaccination among Medicare Beneficiaries 65 Years and Older

ImportanceThe United States Food and Drug Administration conducts routine post-market surveillance of approved vaccines to identify and characterize health outcomes risk associated with vaccination. Pre-licensure clinical trials of RSVPreF3+AS01 and RSVPreF vaccines identified a small number of Guillain-Barre syndrome cases, a serious acute demyelinating disease, following vaccination. ObjectiveTo use Centers for Medicare & Medicaid Services Medicare Fee-for-Service administrative claims and Medicare Part D data to evaluate risk of Guillain-Barre syndrome following respiratory syncytial virus vaccination. Design, Settings, and ParticipantsWe studied vaccines administered between May 3, 2023, when vaccines were first approved, through January 28, 2024. This self-controlled case series study design compared the incidence of Guillain-Barre syndrome during risk intervals of 1-42 days following vaccination to the incidence in subsequent control intervals (43-90 days) among Medicare beneficiaries, aged 65 years and older, enrolled in Fee-for-Service and Medicare Part D. ExposuresReceipt of a single dose of RSVPreF3+AS01 or RSVPreF vaccines. OutcomesGuillain-Barre syndrome was identified using diagnosis code G61.0 in the primary diagnosis position on hospital inpatient claims; returned cases were confirmed via medical record review using Brighton Collaborations case definition. ResultsWe captured approximately 3.23 million Medicare beneficiaries that received respiratory syncytial virus vaccination during the study period. A total of 95 incident Guillain-Barre syndrome cases were observed following respiratory syncytial virus vaccination. In our chart-confirmed self-controlled case series analysis, we observed an increased incidence of Guillain-Barre syndrome following RSVPreF3+AS01 (IRR: 2.46, [95% CI: 1.19, 5.08]) with an attributable risk of 6.5 cases per 1 million doses. We observed an increased, yet not statistically significant, incidence of Guillain-Barre syndrome following RSVPreF (IRR: 2.02, [95% CI: 0.93, 4.40]) with an attributable risk of 9 cases per 1 million doses. Conclusion and RelevanceFindings from this self-controlled case series study suggest an increased risk of Guillain-Barre syndrome during 1-42 days following respiratory syncytial virus vaccination, with fewer than 10 excess Guillain-Barre syndrome cases per 1 million vaccine doses among Medicare beneficiaries 65 years and older. The U.S. Food and Drug Administration maintains that the substantial benefits of RSV vaccination outweigh these identified risks associated with vaccines. Key PointsO_ST_ABSQuestionC_ST_ABSIs there an increased risk of developing Guillain-Barre syndrome (GBS) following vaccination with RSVPreF3+AS01 (AREXVY(R)) and RSVPreF (ABRYSVO(R)) among Medicare beneficiaries aged 65 years and older? FindingsIn a self-controlled case series analysis of Medicare beneficiaries with medical record review, we estimated the incidence rate ratio (IRR) comparing GBS in pre-specified risk and control intervals following vaccination with RSVPreF3+AS01 (IRR: 2.46, 95%CI: 1.19-5.08) or RSVPreF (IRR: 2.02, 95%CI: 0.93-4.40). RSV vaccines were associated with fewer than 10 excess GBS cases per 1 million vaccine doses. MeaningThese findings suggest an increased risk of GBS following RSV vaccination.