Although COVID-19 vaccination was associated with a transient increase in the incidence of Guillain-Barre syndrome (GBS) and Bell palsy, it was unclear whether the association was causal, and outcomes of both conditions were sufficiently rare to encourage continued confidence in the safety of COVID-19 vaccination. These findings were published in Vaccine.
Investigators obtained data captured from the primary care records of approximately 40% of the adult population in England who received at least one dose of a COVID-19 vaccine. Eligible participants included those who experienced new-onset GBS, Bell Palsy, or transverse myelitis following vaccination with either the ChAdOx1, BNT162b2, or mRNA-1273 vaccine. The study start date was July 1, 2020, providing a 5-month prevaccination comparison period before the COVID-19 vaccination program began in December 2020; the study concluded on July 7, 2021. The primary outcomes were the incidence of GBS, transverse myelitis, or Bell palsy. Using unadjusted conditional Poisson regression, separate analyses were conducted for all 3 COVID-19 vaccines. A secondary analysis also was performed to assess outcomes following receipt of subsequent vaccine doses administered 21 days or more after the first dose.
Among a total 7,783,441 participants who received the ChAdOx1 vaccine, new-onset GBS, transverse myelitis, and Bell palsy occurred in 517, 199, and 5350 participants, respectively. Receipt of the first dose of the ChAdOx1 vaccine was associated with an increased risk for incident GBS (incidence rate ratio [IRR], 1.85; 95% CI, 2.33-3.47) and Bell palsy (IRR, 1.39; 95% CI, 1.27-1.53), with an attributable risk of 11.0 and 17.9 per 1 million participants, respectively. The occurrence of GBS and Bell palsy was increased among participants aged between 40 and 64 years compared with those older than 65 years. No clear associations were observed between ChAdOx1 vaccination and an increased risk for transverse myelitis. The secondary analysis performed following receipt of the second vaccine dose did not show a significant increase in the incidence of GBS or Bell palsy.
Among a total of 5,729,152 participants who received the BNT162b2 vaccine, new-onset GBS, transverse myelitis, and Bell palsy occurred in 283, 109, and 3609 participants, respectively. Of note, the incidence of each of these outcomes following vaccination was no different compared with the period prior to vaccination. There also was no significantly increased risk for these outcomes following receipt of the second BNT162b2 vaccine dose. Results of a ratio-of-ratios comparison showed that the rate of postvaccination GBS was twice as high among participants who received the ChAdOx1 vaccine compared with those who received the BNT162b2 vaccine (ratio of IRRs, 2.40; 95% CI, 1.57-3.66). Further analysis between participants who received these 2 vaccines showed that the rate of Bell palsy was approximately 50% higher among those who received the ChAdOx1 vaccine (ratio of IRRs, 1.48; 95% CI, 1.25-1.76).
Among a total of 255,446 participants who received the mRNA-1273 vaccine, Bell palsy occurred in 78. There were too few outcomes of GBS or transverse myelitis among the study population to warrant further investigation. There also was no evidence of an increase in the incidence of Bell palsy following receipt of the first mRNA-1273 vaccine dose.
This study was limited by potential ascertainment bias, and there was a small overlap in diagnoses of Bell palsy and GBS.
The investigators noted that outcomes of GBS, Bell Palsy, and transverse myelitis following COVID-19 vaccination were “sufficiently rare.” They concluded, “[these] findings should encourage continued confidence in [COVID-19] vaccination for policy-makers, [clinicians], and the public.”
Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures
Walker JL, Schultze A, Tazare J, et al. Safety of COVID-19 vaccination and acute neurological events: A self-controlled case series in England using the OpenSAFELY platform. Vaccine. Published online June 7, 2022. doi:10.1016/j.vaccine.2022.06.010