Bell's Palsy in COVID-19 Vaccine Trials: Why You Shouldn't Worry

Reports released from Pfizer and Moderna show that seven COVID-19 vaccine trial participants experienced a type of facial paralysis, called Bell's palsy, in the weeks after vaccination. This rare side effect, in tandem with three reports of severe allergic reactions, has raised some alarm about the safety of the new vaccines.

An analysis of the number of Bell's palsy incidents reported so far, however, shows the rate is no higher than the number of people who experience Bell's palsy in the general population. 

 According to the National Institutes of Health, Bell's palsy affects about 40,000 people in the United States every year, which is 0.01% of Americans. 

In the Pfizer-BioNTech clinical trial, which included 44,000 participants, 4 people reported experiencing Bell's palsy, which is 0.0091% of participants. The incidents were reported 3,9, 37, and 48 days after vaccination. No cases of Bell's palsy were reported in the placebo group.

In the Moderna clinical trial, which included 30,400 participants, 3 people reported experiencing Bell's palsy, which is 0.099% of participants. One person was in the placebo group. Among the three not in the placebo group, the Bell's palsy incidents were reported 32, 28, and 22 days after vaccination. 

While the U.S. Food and Drug Administration (FDA) briefing documents provided by Pfizer and Moderna indicate these rates of Bell's palsy "do not represent a frequency above that expected in the general population," the FDA recommends surveillance for Bell's palsy as the vaccines are distributed among the general population.  

For anyone who does experience Bell's palsy, the condition is treatable. Oral steroids, especially if administered within 72 hours of symptom onset, are highly effective at restoring nerve function.