Rates of neurological events higher with SARS-CoV-2 infection than with COVID-19 vaccine

Incidence rates for Bell’s palsy, encephalomyelitis and Guillain-Barré syndrome were higher in unvaccinated people with SARS-CoV-2 infection compared with those vaccinated against COVID-19, researchers reported in BMJ.

“Immune-mediated neurological disorders have been identified as adverse events of special interest by regulators, such as the FDA in the U.S. and the EMA in Europe,” Xintong Li, MHS, a doctoral student at the Center for Statistics in Medicine at the University of Oxford, and colleagues wrote. “These adverse events of special interest have been closely monitored during immunization campaigns, and several severe neurological disorders were reported as rare adverse events during the first clinical trials of COVID-19 vaccines.”

Li and colleagues conducted a population-based, historical rate comparison study using primary care records from the United Kingdom and Spain to assess rates of neurological events in 8,330,497 individuals who received at least one dose of a COVID-19 vaccine and in 735,870 unvaccinated individuals who tested positive for SARS-CoV-2.

Investigators assessed incidence rates for Bell’s palsy, encephalomyelitis and Guillain- Barré syndrome for the vaccinated group 21 days after receiving a vaccine dose and 90 days post-infection for those who were unvaccinated.

Among 3,776,803 participants who received a vaccine dose from AstraZeneca, there were 117 observed cases of Bell’s palsy, compared with 164.5 expected cases (standardized incidence ratio = 0.71; 95% CI, 0.59-0.85). Among 1,693,453 participants who received a dose from Pfizer, 46 cases of Bell’s palsy were observed compared with 116.4 expected cases (SIR = 0.40; 95% CI, 0.30-0.53). Participants who tested positive for SARS-CoV-2 infection had a reported 53 cases, higher than the 39.8 expected cases (SIR = 1.33; 95% CI, 1.02-1.74).

Post-vaccine rates of encephalomyelitis and Guillain-Barré syndrome were consistent with expected rates in both vaccination groups. However, higher rates for both conditions were reported in the SARS-CoV-2 group (encephalomyelitis: SIR = 6.89; 95% CI, 3.82-12.44 and Guillain-Barré syndrome: SIR = 3.53; 95% CI, 1.83-6.77).

“We found no safety signal for any of the studied immune-mediated neurological events after vaccination against COVID-19,” Li and colleagues wrote. “Infection with SARS-CoV-2 was, however, associated with an increased risk of Bell’s palsy, encephalomyelitis and Guillain-Barré syndrome.”