A postlicensure safety study of a meningococcal conjugate vaccine in Southern California has shown that the vaccine may be associated with an increase in the risk of Bell’s palsy, but only if the vaccine is taken concomitantly with another vaccine.
Researchers set out to evaluate the safety of one quadrivalent meningococcal conjugate vaccine, MenACWY-CRM. Two MenACWY vaccines are currently licensed in the United States; MenACWY-D is the other. The vaccines underwent studies on the road to approval, but researchers saw an absence of data about how the vaccine was faring in routine clinical use.
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Researchers looked through the electronic health records of the study population for “26 prespecified events of interest (EOIs) under investigation, including neurologic, rheumatologic, hematologic, endocrine, renal, pediatric, and pediatric infectious disease EOIs. Occurrence of incident episodes of these EOIs was identified during a 1-year observation period after the index vaccination for each individual.”
They identified 4,240 EOIs, but dismissed 3,000 of them as probable preexisting conditions. With what was left, some of the EOIs did not occur at all (such as Guillain-Barré syndrome, myasthenia gravis, or systemic lupus erythematosus). Of transverse myelitis and autoimmune hemolytic anemia, among others, there was only 1 case.
Seizure, iridocyclitis, Hashimoto’s disease, and anaphylaxis initially showed statistically significant risk incidence, but were all ruled out (of the hypothesis of possible cause by vaccination) by further review from a physician investigator.
But in the case of Bell’s palsy, the independent case review committee did not rule out the possibility that the MenACWY-CRM vaccine increased the risk incidence of the condition.
However, the increased risk was present only for subjects who received a concomitant vaccine along with the MenACWY-CRM, such as Tdap, influenza, or human papillomavirus vaccine. “Stratified analyses demonstrated an increased risk for Bell’s palsy in subjects receiving concomitant vaccines (risk incidence, 5.0; 95% confidence interval, 1.4-17.8), and no increased risk for those without concomitant vaccine (RI, 1.1; 95% CI, 0.2-5.5),” Dr. Tseng and his coauthors wrote. All eight cases of Bell’s palsy resolved completely.
They concluded, “we observed a temporal association between occurrence of Bell’s palsy and receipt of MenACWY-CRM concomitantly with other vaccines. The association needs further investigation because it could be due to chance, concomitant vaccination, or underlying medical history predisposing to Bell’s palsy.”
Dr. Tseng and numerous coauthors reported receiving research support from Novartis Vaccines, the sponsor of the study. Three coauthors were employees of Novartis at the time of the study.