The benefits of influenza vaccines outweigh the insignificant risk for Guillain-Barré syndrome (GBS) following influenza vaccinations, according to a study published in the Journal of Infectious Diseases.
During the 2018 to 2019 influenza season, the Vaccine Safety Datalink (VSD), a collaborative project between the CDC and 8 integrated health organizations, identified a statistical signal for an increased risk of GBS on days 1 to 42 post-vaccination with the 2018-2019 high-dose influenza vaccine (IIV3-HD). Study authors conducted claims-based self-controlled risk interval analyses among Medicare patients 65 years of age and older to assess this signal.
In total, 7,453,690 patients who received a IIV3-HD vaccination in the early-season and 14,437,945 patients who received a IIV3-HD vaccination at the end-of-season were included and analyzed. Post-vaccination days 8 through 21 and days 1 through 42 were used as risk windows, and post-vaccination days 43 through 84 were used as a control window. Additionally, the VSD performed chart-confirmed analyses on 646,996 IIV3-HD vaccinations.
Results suggested that there are no statistically significant increases in GBS risk following IIV3-HD administration in the 2018-2019 influenza season. In the early-season analyses, there was no statistically significant increase in GBS risk observed in either 8 to 21 days post-vaccination (odds ratio [OR] 1.85; 95% CI, 0.99-3.44) or 1 to 42 days post-vaccination (OR, 1.31; 95% CI 0.78-2.18) risk windows. In the end-of-season analyses, there was no statistically significant increase in GBS risk observed in either 8 to 21 days post-vaccination (OR 1.64; 95% CI 0.92-2.91) or 1 to 42 days post-vaccination (OR, 1.12; 95% CI 0.70-1.79) risk windows.
A final chart review by the VSD identified 1 case of GBS in both the risk (onset, day 1) and control windows, a relative risk of 1.00 (95% CI, 0.06-15.99), and determined it to be statistically insignificant.
While the study does “not exclude an association between 2018-2019 IIV3-HD and GBS,” study authors “determined that, if such risk existed, it was low.” A chart-confirmed VSD result also did not confirm an increased risk of GBS.
Perex-Vilar S, Hu M, Weintraub E, et al. Guillan-barré syndrome after high-dose influenza vaccine administration in the United States, 2018-2019 Season. J Infect Dis. Published online November 2, 2020. doi: 10.1093/infdis/jiaa543.