There is no association between the SARS-CoV-2 vaccine and the risk for new-onset seizure, data from a new meta-analysis of six randomized, placebo-controlled clinical trials (RCTs) showed.
Results of the pooled analysis that included 63,500 individuals vaccinated with SARS-CoV-2 and 55,000 who received a placebo vaccine showed there was no significant difference between the two groups with respect to new-onset seizures at 28- or 43-day follow-up.
Regarding new-onset seizures in the general population, there was no statistically significant difference in risk for seizure incidence among vaccinated individuals vs placebo recipients, according to our meta-analysis, wrote the investigators, led by Ali Rafati, MD, MPH, Iran University of Medical Sciences in Tehran.
The findings were published online in JAMA Neurology.
Mixed Results
Results from previous research have been mixed regarding the link between the SARS-CoV-2 vaccination and new-onset seizures, with some showing an association.
To learn more about the possible association between the vaccines and new-onset seizures, the researchers conducted a literature review and identified six RCTs that measured adverse events following SARS-CoV-2 vaccinations (including messenger RNA, viral vector, and inactivated virus) vs placebo or other vaccines.
While five of the studies defined new-onset seizures according to the Medical Dictionary for Regulatory Activities, trial investigators in the sixth RCT assessed and determined new-onset seizures in participants.
Participants received two vaccinations 28 days apart in five RCTs and only one vaccine in the sixth trial.
The research team searched the data for new-onset seizure in the 28 days following one or both COVID vaccinations.
No Link Found
After comparing the incidence of new-onset seizure between the 63,500 vaccine (nine new-onset seizures, 0.014%) and 55,000 placebo recipients (one new-onset seizure, 0.002%), investigators found no significant difference between the two groups (odds ratio [OR], 2.70; 95% CI, 0.76-9.57; P = .12)
Investigators also sliced the data several ways to see if it would yield different results. When they analyzed data by vaccine platform (viral vector) and age group (children), they didn’t observe significant differences in new-onset data.
The researchers also searched for data beyond the month following the injection to encompass the entire blinded phase, so they analyzed the results of three RCTs that reported adverse events up to 162 days after the vaccine.
After pooling the results from the three studies, investigators found no statistical difference between the vaccine and placebo groups in terms of the new-onset seizure (OR, 2.31; 95% CI, 0.86%-3.23; P > .99)
Study limitations included the missing information on vaccine doses or risk factors for the development of seizures. Also, the RCTs included in the meta-analysis were conducted at different times, so the SARS-CoV-2 vaccines may have differed in their composition and efficacy.
“The global vaccination drive against SARS-CoV-2 has been a monumental effort in combating the pandemic. SARS-CoV-2 vaccinations that are now available appear safe and appropriate,” the authors wrote.
There were no study funding sources or disclosures reported.
A version of this article appeared on Medscape.com.