New-Onset Seizure After COVID Vaccine: Is There a Significant Risk?

There is no significant difference between the risk of developing new-onset seizures after receiving the COVID vaccine among vaccinated vs unvaccinated individuals, according to study results published in JAMA Neurology.

Researchers conducted a systematic review and meta-analysis to assess seizure incidence among individuals vaccinated against SARS-CoV-2 vs those who received placebo. The researchers included phase 3 randomized clinical trials reporting seizure incidence with SARS-CoV-2 vaccination that were conducted between December 2019 and July 2023 in the study. The primary outcome was new-onset seizure incidence among recipients of SARS-CoV-2 vaccine and placebo. Odds ratio (OR) and 95% CI were calculated for the measure of effect. Between-study heterogeneity was assessed by Cochran Q using I² index.

A total of 6 trials met the inclusion criteria. In 5 studies, participants received 2 injections of vaccine or placebo 28 days apart. In the remaining study, participants received only 1 injection.

The pooled study population comprised 63,521 vaccine recipients and 54,919 placebo recipients.

In the 28 days after each vaccine or placebo injection, 0.014% of vaccine recipients and 0.002% of placebo recipients had incident seizure, indicating no statistically significant difference between the 2 groups (OR, 2.70; 95% CI, 0.76-9.57; P =.12; I², 0%).

In a subgroup analysis, the incidence of seizure did not differ among adults receiving viral vector vaccines vs placebo (OR, 3.63; 95% CI, 0.60-22.00; P =.28; I², 14%) or children receiving mRNA vaccines vs placebo (OR, 1.00; 95% CI, 0.10-9.61; P >.99; I², 0%).

After pooling the 3 studies that reported the results of the entire double-blinded phase, no statistical difference was observed between the vaccine and placebo groups (OR, 2.31; 95% CI, 0.86-3.23; P >.99; I², 0%).

In a pooled analysis on other neurologic adverse events, there was no significant difference in the incidence of ischemic stroke (OR, 3.64; 95% CI, 0.60-22.11; P =.16; I², 0%), severe headache (OR, 1.16; 95% CI, 0.54-2.50; P =.70; I², 0%), or syncope (OR, 1.16; 95% CI, 0.54-2.50; P =.69; I², 0%) among recipients of vaccine vs placebo.

Study limitations included the lack of patient-level data, missing data regarding additional risk factors for the development of seizures, and reporting bias.

“Regarding new-onset seizures in the general population, there was no statistically significant difference in risk of seizure incidence among vaccinated individuals vs placebo recipients, according to our meta-analysis,” the researchers concluded.