Respiratory syncytial virus (RSV) is a highly contagious virus that causes severe respiratory illness, leading to approximately 177,000 hospitalizations and 14,000 deaths annually among adults aged 65 and older [1]. Individuals with weakened immune systems are particularly at risk for severe complications from RSV [2]. RSV vaccines have proven to be highly effective in preventing severe illness, with clinical trials showing efficacy rates of 70-80%, including in immunocompromised individuals [3]. In January 2025, the FDA issued a warning about a potential link between Guillain-Barré syndrome (GBS) and RSV vaccines produced by Pfizer (Abrysvo) and GSK (Arexvy). The warning was based on data from a vaccine adverse event reporting system, which indicated 7-9 excess cases of GBS per million doses of Abrysvo or Arexvy given to individuals aged 65 and older. While this suggests a slight increased risk of GBS in the 42 days following vaccination, it is unclear whether RSV vaccination directly causes GBS. It is also worth noting that although rare, cases of GBS have been reported following RSV infections as well [4]. The GBS/CIDP Foundation recommends discussing the RSV vaccine with your doctor to assess its suitability for you. Despite the apparent very small risk of GBS, we believe that the benefits of the RSV vaccine—given the commonality of RSV infections and its proven effectiveness in preventing severe illness and complications—generally outweigh the potential risks and encourage vaccination especially in older and immunocompromised individuals.
[1] Centers for Disease Control and Prevention. Respiratory Syncytial Virus Infection (RSV). Updated 12/18/2020. Accessed 12/10/2021, https://www.cdc.gov/rsv/research/us-surveillance.html
[2]. Nowalk MP et al. Estimating the burden of adult hospitalized RSV infection including special populations. Vaccine. 2022 Jun 3;40(31):4121–4127. doi: 10.1016/j.vaccine.2022.05.077.
[3] Payne AB et al. Respiratory syncytial virus (RSV) vaccine effectiveness against RSV-associated hospitalisations and emergency department encounters among adults aged 60 years and older in the USA, October, 2023, t March, 2024: a test-negative design analysis. The Lancet. 2024;404, 1547-1559.
[4] Gupta M et al. A Case of Pediatric Guillain-Barré Syndrome After Respiratory Syncytial Virus Infection. Pediatr Neurol. 2023 Sep:146:129-131.