Can vaccines cause Guillain-Barré syndrome?
Here is what the checked sources say. Each title links to the original.
Association between Guillain-Barré syndrome and influenza A (H1N1) 2009 monovalent inactivated vaccines in the USA: a meta-analysis
Pooled data from six US safety monitoring systems covering about 23 million people vaccinated against 2009 H1N1 flu. The 2009 H1N1 vaccines were associated with a small increased risk of Guillain-Barré syndrome (GBS), a rare condition where the immune system damages nerves and causes weakness: incidence rate ratio 2.35 (95% CI 1.42 to 4.01), about 1.6 extra cases per million people vaccinated. The authors say this matches earlier seasonal flu vaccine estimates and, citing the pandemic's illness and deaths and the vaccine's effectiveness, that benefits greatly outweigh the risks. The abstract does not quantify the benefit.
Assessing the risk of Guillain-Barré syndrome in older adults after bivalent RSV pre-F vaccination in England
The UK Health Security Agency studied GBS after Pfizer's RSV vaccine (Abrysvo) in England's program for 2.5 million adults aged 75 to 79, which began in September 2024. Several methods found an increased rate of GBS in the 42 days after vaccination; the final self-controlled analysis estimated 3.34 times the usual rate (95% CI 2.12 to 5.28), about 23 extra cases per million doses (17 to 26). The authors call the risk small and far exceeded by the vaccine's benefits, which the abstract does not quantify. UKHSA charges vaccine makers a cost-recovery fee for required safety reports.
Vaccines and Guillain-Barré Syndrome
Plain-language overview from CHOP. The 1976 swine flu vaccine was estimated to cause GBS in about 1 per 100,000 recipients; flu vaccine risk since then has varied by season. An Ontario study (1993 to 2011) found about 1 GBS admission per million vaccinations versus 17 per million flu infections, which CHOP says suggests flu vaccine may, on balance, prevent GBS. Shingrix and the J&J COVID-19 vaccine have occasionally been linked to GBS. CHOP cites studies finding current routine MMR, HPV, meningococcal, polio, pneumococcal, chickenpox and hepatitis vaccines were not associated with increased GBS risk.
FDA Requires Guillain-Barré Syndrome (GBS) Warning in the Prescribing Information for RSV Vaccines Abrysvo and Arexvy: FDA Safety Communication
On January 7, 2025, the FDA required the two RSV vaccines named in this notice, Pfizer's Abrysvo and GSK's Arexvy, to add a Guillain-Barré syndrome warning to their prescribing information. For each, the new wording says results of a post-marketing observational study suggest an increased risk of GBS during the 42 days after vaccination. The notice describes a suggested increased risk and does not give a rate. It explains GBS as a rare disorder in which the immune system damages nerve cells, causing weakness and sometimes paralysis.