The Pfizer Covid-19 vaccine is now being given and it looks like the Moderna vaccine will be given Emergency Use Authorization by the FDA this week. Today's news reports four cases of Bells Palsy during the vaccine trials for Pfizer and three for people who received the Moderna vaccine. (one Bells Palsy happened in a person who received placebo). The CDC says it will be looking out for any reports of Bells Palsy going forward.
What is Bells Palsy? It is a sudden drooping of 1/2 of the face and it is thought to be from inflammation of the facial nerve. We don't know what causes it but we think it is a result of a virus. It is seen with herpes, shingles, mono, mumps, and even influenza. The paralysis resolves within a few weeks in 85% of people. Some take longer to resolve and less than 5% have any permanent damage. People who receive corticosteroids early in the course of Bells Palsy seem to recover faster. A number of famous people have had Bells Pals, including Angelina Jolie, Pierce Brosnon, George Clooney and Katie Holmes.
The usual background rate in the general population for getting Bells Palsy is 12-25 per 100,000 people. The Pfizer rate was 9.3/100,000; less than the rate without the vaccine.
Pfizer had 4 cases of Bells Palsy out of 43K people vaccinated. Moderna had 4 cases out of 30K people and one of them received placebo
It is important to monitor any side effect from a vaccine, especially a new one. But in this case we do not know if it was a cause/effect or just a normal event that would have occurred anyway. We will be watching closely as the vaccines roll out and I am not aware of any medical professional who considers this a problem. The side effects we are seeing with the vaccine are extremely minor - slight fever, headache and maybe arm pain.