No Detectable Association Between mRNA COVID-19 Vaccines and Facial Paralysis

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While several cases of facial paralysis were observed during the phase 3 clinical trials of the mRNA COVID-19 vaccine, a causal relationship could not be established. With the US Food and Drug Administration recommending monitoring of vaccine recipients, the researchers looked at a disproportionality analysis using the WHO’s pharmacovigilance database, VigiBase.

Compared with other viral vaccines, the mRNA COVID-19 vaccines do not display a signal for facial paralysis. And, if there is an association, the risk is likely low according to a research letter published in JAMA Internal Medicine.

After facial paralysis was observed during phase 3 trials of mRNA COVID-19 vaccines, investigators used the hypothesis-generating method of disproportionality analysis to investigate a putative association between the vaccines and facial paralysis.

Using data from the World Health Organization’s pharmacovigilance database, VigiBase, a total of 844 (0.6%) facial paralysis-related events were identified among the 133,883 cases of adverse drug reactions reported with mRNA COVID-19 vaccines. This included 683 cases of facial paralysis, 168 cases of facial paresis, 25 cases of facial spasms, and 13 cases of facial nerve disorders.

A total of 749 and 95 cases were reported with the Pfizer-BioNTech and Moderna vaccines, respectively. The number of facial paralysis cases reported among 1,265,182 adverse drug reactions with other viral vaccines, or 314,980 influenza vaccines was 5734 (0.5%) and 2087 (0.7%), respectively.

No signal of disproportionality of facial paralysis for broad and narrow definitions versus other viral vaccines (IC025 = −0.01 and IC025 = −0.06) or influenza vaccines alone (IC025 = −1.36 and IC025 = −0.32) was detectable.

Investigators acknowledge that despite adjusting for sex and age, the results may be influenced by residual confounding and reporting bias. However, “despite

selective reporting and a potential delay in reporting and transferring cases among pharmacovigilance databases, the reporting rate of facial paralysis after mRNA COVID-19 vaccination found in the present study is not higher than that observed with other viral vaccines.” They conclude that if any association between facial paralysis and mRNA vaccination does exist, the risk is likely very low.


Renoud L, Khouri C, Revol B, et al. Association of facial paralysis with mRNA COVID-19 vaccines a disproportionality analysis using the world health organization pharmacovigilance database. JAMA Intern Med. Published online April 27, 2021. doi:10.1001/jamainternmed.2021.2219