Question: Is there an increase in risk of Bell’s Palsy in recipients of the recently-approved mRNA vaccines by Moderna and by Pfizer?
Answer: This article argues that the data from two vaccine trials indicate the possibility of such an increased risk. Across two studies, one of each vaccine, there were 7 cases of Bell’s Palsy in the vaccine groups, but only 1 case in the placebo groups. The number of persons receiving the vaccine were about equal to the number of persons receiving the placebo. But the number of cases of Bell’s Palsy was higher for those receiving the vaccine instead of the placebo. Now the FDA has said that these cases were is due to the background rate of cases. But the FDA also recommended further surveillance, as the vaccines are distributed.
Question: Should people refuse these mRNA types of vaccines?
Answer: No. You should still receive the vaccine. The risk of Bell’s Palsy from these vaccinations is still small, even though the rate seems to be higher than the background rate of occurrence of Bell’s Palsy. By comparison, the risk from Covid-19 is very grave and much more likely. Also, Bell’s Palsy is treatable and most persons fully recover.
What Is Bell’s Palsy?
National Institutes of Health: “The cause of Bell’s palsy is unknown. Swelling and inflammation of the cranial nerve VII is seen in individuals with Bell’s palsy. Most scientists believe that reactivation of an existing (dormant) viral infection may cause the disorder. Impaired immunity from stress, sleep deprivation, physical trauma, minor illness or autoimmune syndromes are suggested as the most likely triggers. As the facial nerve swells and becomes inflamed in reaction to the infection, it causes pressure within the Fallopian canal (a bony canal through which the nerve travels to the side of the face), leading to the restriction of blood and oxygen to the nerve cells. In some mild cases where recovery is rapid, there is damage only to the myelin sheath (the fatty covering that acts as insulation of nerve fibers).” [National Institutes of Health: Bell’s Palsy Fact Sheet]
Mayo Clinic online: “The symptoms of Bell’s palsy include sudden weakness in your facial muscles. In most cases, the weakness is temporary and significantly improves over weeks. The weakness makes half of your face appear to droop. Your smile is one-sided, and your eye on that side resists closing.” [Mayo Clinic online]
The Covid-19 Vaccination Trials
The Moderna and Pfizer vaccines were each tested in tens of thousands of participants, each in its own Phase 3 trial. With each trial, there were more cases of Bell’s Palsy in the persons receiving the vaccine as compared to the persons receiving the placebo. (In this article, BP stands for Bell’s Palsy.)
Moderna: 3 cases in the vaccine group, one case in the placebo group.
Pfizer: 4 cases in vaccine group, zero cases in placebo group.
Combining the data, there were 7 cases of BP in the vaccination groups, and 1 in the placebo groups.
Is it possible that the vaccinations caused Bell’s Palsy by causing an inflammation of the facial nerve? Perhaps. A vaccination stimulates the immune system which can result in inflammation.
A Closer Look
In a document on the Pfizer vaccine, the FDA has said “Observed frequency consistent with background rate in general population” [FDA on Pfizer Vaccine]. In other words, they are saying that the rate of occurrence of Bell’s Palsy in each trial was about the same as in the general population. This means that they think these cases of BP may have occurred by random chance, and these persons would have contracted BP, even if they had not been vaccinated. However, the same FDA document also stated that there was “Higher frequency in vaccine group vs. placebo” and that they recommend “further surveillance”.
Media articles have generally repeated the claim that the number of cases of BP was the same as would be expected from the background rate of this illness in the general population. That assertion is false, as this article will show. The number of cases in the vaccine groups were higher than the background rate for Bell’s Palsy.
First of all, when we combine the two studies, the ratio of those contracting BP is 7 to 1. Of those vaccinated, 7 came down with BP, and of those receiving the placebo, only one did. If you were going to do a study of whether the vaccinations with mRNA increase the likelihood of Bell’s Palsy, you would take tens of thousands of persons, give half the vaccine and the other half a placebo, and then look for an imbalance in the rate of BP. But we already have that data. A ratio of 7 to 1 indicates that it is possible, even probable, that these mRNA vaccinations increase the likelihood of BP.
In addition to the imbalance between the vaccine and placebo groups, the claim that cases of BP occurred by random chance does not take into account the length of time of each trial. The rate of occurrence of Bell’s Palsy in the general population is based on number of cases per 100,000 of the population per year (12 months). “In the United States, the annual incidence of Bell palsy is approximately 23 cases per 100,000 persons.” [Medscape.com]
Moderna vaccine: “Throughout the same period*, there were three reports of Bell’s palsy in the Moderna COVID-19 Vaccine group (one of which was a serious adverse event), which occurred 22, 28, and 32 days after vaccination, and one in the placebo group which occurred 17 days after vaccination. Currently available information on Bell’s palsy is insufficient to determine a causal relationship with the vaccine.” [Source: FDA]
* The “same period” is 28 days after each vaccination shot, and the on-going monitoring after the second shot.
Pfizer vaccine: “Throughout the safety follow-up period to date, Bell’s palsy (facial paralysis) was reported by four participants in the Pfizer-BioNTech COVID-19 Vaccine group. Onset of facial paralysis was Day 37 after Dose 1 (participant did not receive Dose 2) and Days 3, 9, and 48 after Dose 2. No cases of Bell’s palsy were reported in the placebo group. Currently available information is insufficient to determine a causal relationship with the vaccine.” [Source: FDA]
For Pfizer, all of the BP cases occurred within a 48-day period of time. And for both Moderna and Pfizer, the BP cases occurred 3 weeks or more after the first dose. The placebo group from Pfizer had zero BP cases; the Moderna placebo group had only one, 17 days after the placebo shot was given. The fact that all BP cases, except for one in the placebo group, occurred 3 weeks or more after vaccination suggests a connection to the vaccination shot.
The time period of the cases of BP across both trials is the period starting from when the patients were monitored for adverse reactions to the vaccine or placebo. The latest occurrence of BP was 48 days after dose 2 of the Pfizer vaccine, and dose 2 occurs 21 days after dose 1. So that is a period of 59 days, or about 2 months.
But the rate of occurrence of BP as 23 cases per 100,000 in the U.S. is per 12 months. That rate applied to a 2-month period is 3.83 cases per 100,000 persons every two months. And then the number of persons receiving both vaccines was as follows. And the number per every 37,000 persons in the population is lower still: 1.4 cases of Bell’s Palsy per 37,000 persons in the general population.
Moderna: “The safety of Moderna COVID-19 Vaccine was evaluated in an ongoing Phase 3 randomized, placebo-controlled, observer-blind clinical trial conducted in the United States involving 30,351 participants 18 years of age and older who received at least one dose of Moderna COVID-19 Vaccine (n=15,185) or placebo (n=15,166) (NCT04470427).” [Source: FDA]
Pfizer: “43,448 participants (21,720 Pfizer-BioNTech COVID-19 Vaccine; 21,728 placebo) in Phase 2/3” [Source: FDA]
Total vaccinated: 15,185 plus 21,720 equals 36,905.
Total placebo: 15,166 plus 21,728 equals 36,894.
The background rate of 23 cases of Bell’s Palsy per 100,000 per year (12 months) translates into 1.4 cases of Bell’s Palsy per 37,000 persons in the population per two-months. (Reducing the value for 36,905 or 36,894 persons still gives us a value rounded to 1.4, specifically 1.415 or 1.414).
So we should expect 1.4 cases of Bell’s Palsy in the placebo group (both trials combined), which has 36,894 persons and covered a two-month period. And the actual number of cases was one. So that value agrees with the background rate of occurrence of Bell’s Palsy.
But the value for both vaccination groups combined, Pfizer and Moderna, is 7 cases in a population of 36,905 persons. The actual value should have been 1 or 2, specifically, there should have been one case, with a 41% chance of a second case. Instead, there were 7 cases. So 7 cases instead of 1.4 cases is 5 times too many cases. And that is outside of statistically likelihood.
The actual rate for those receiving the placebo was one case per 36,894 persons per two months, which is 6 cases expected per 36,894 persons per year, which is a rate of 16.26 cases of Bell’s Palsy per 100,00 persons per year. This is within the range of rates of occurrence (see above) in various studies (15 to 30 or 11 to 53).
If 7 cases per 36,905 in two months were the background rate of occurrence, there would be 42 cases per 12 months, and 113.8 cases of Bell’s Palsy per 100,000 persons per year. But the real background rate is only 23 cases, not 113.8 cases. So 7 cases per 36,905 persons is far above the background rate.
HOWEVER,** this does not mean that we can expect 113.8 cases of Bell’s Palsy per 100,000 vaccinated persons. The risk is only across 2 months, not 12 months. So the risk of BP among vaccinated persons (Moderna or Pfizer mRNA vaccines) is 7 per 36,905 or 1 in every 5272. Which is 19.00 cases of BP in every 100,000 persons vaccinated. But subtract from those 19 cases the 3.833 cases from the background rate per 2 months per 100,000 persons. So then 15.167 of those 19.00 cases of BP within 2 months after vaccination are from the vaccine, and the other 3.833 cases are background risk.
For every million persons vaccinated, we can expect 190 cases of BP (151.67 of which are from the vaccine; 38.33 of which are background risk cases).
So that is the problem with the common explanation: the rate of occurrence used to explain away the cases of BP is per person per year. And when we change the rate to the time period in question and the number of persons in question, the number of cases in the placebo group, one, is the correct usual rate. That case occurred by random chance in a group that size. But the number of cases in the vaccine group is about 5 times too high. At least 5 or 6 of those cases were due to the vaccination.
Why Would This Vaccine Cause BP?
“The cause of Bell’s palsy is unknown. Swelling and inflammation of the cranial nerve VII is seen in individuals with Bell’s palsy. Most scientists believe that reactivation of an existing (dormant) viral infection may cause the disorder.” [National Institutes of Health: Bell’s Palsy Fact Sheet]
Both mRNA vaccines can cause headaches, muscle and joint pain, chills, fever, and fatigue. These symptoms can be caused by inflammation in the brain, muscles, and joints. Vaccines also commonly cause inflammation in the site of the injection. And inflammation is an indication of the immune system working, which of course has to occur after a vaccination. So it makes sense that a vaccine might have the side effect of inflammation of a cranial nerve, in this case Bell’s Palsy.
What Did The FDA Say About Bell’s Palsy?
On the Moderna vaccine: “Causality assessment is confounded by predisposing factors in these participants. However, considering the temporal association and biological plausibility, a potential contribution of the vaccine to the manifestations of these events of facial palsy cannot be ruled out. FDA will recommend surveillance for cases of Bell’s palsy with deployment of the vaccine into larger populations.” [FDA.gov, with my emphasis]
On the Pfizer Vaccine: “Bell’s palsy
“Vaccine n=4, placebo n=0
“Observed frequency consistent with background rate in general population
“No clear basis upon which to conclude a causal relationship at this time
“Higher frequency in vaccine group vs. placebo ” [FDA.gov
The claim of consistency with background rate in general population is clearly not correct, when we take into account the period of time and the number of participants receiving the vaccine.
However, about the Pfizer vaccine, the same FDA document also states: “As of data the cutoff, 4 cases of Bell’s palsy were reported in vaccine recipients, and none in placebo recipients. Although there is no clear basis upon which to conclude a causal relationship at this time, FDA recommends further surveillance if vaccine is authorized for widespread use.” [FDA.gov
The FDA is claiming this is due to the background rate of occurrence, but also recommending further surveillance. They also state that a causality between the vaccine and these cases of Bell’s Palsy cannot be ruled out.
What Is The Expected Rate of Bell’s Palsy from the Vaccine?
The background rate in the general population in the U.S. is 23 per 100,000 per year.
But if the vaccine is causing additional cases, then the combined rate (background rate plus cases caused by vaccine) would be 19.00 cases per 100,000 vaccinated. That is one or two (most likely 2) cases of Bell’s Palsy per 1000 persons vaccinated.
Now if that is the case, it will take more than 3 weeks from the start of the vaccinations to begin to see cases of Bell’s Palsy. Since healthcare workers are first to receive, and nursing home residents right after them, these are the populations that are at risk of Bell’s Palsy in the next month or so. We should watch those recipients, and see how many cases of Bell’s Palsy occur.
Update: as of Dec. 24th just over 1 million U.S. residents have received one or the other of the mRNA vaccines. If the math above is correct, then within a month or two, there will be about 190.0 cases of Bell’s Palsy in vaccine recipients, And the U.S. is aiming for 100 million vaccinations by the end of 2021’s first quarter, which, again if the math is correct, could result in as many as 19,000 cases of Bell’s Palsy before the end of the second quarter, 2021.
Please note that Pfizer and Moderna combined are planning on making billions of doses of these mRNA vaccines. This could potentially result in many cases of Bell’s Palsy. But it is too soon to tell. I agree with this FDA statement: “FDA will recommend surveillance for cases of Bell’s palsy with deployment of the vaccine into larger populations.”
Should You Still Receive These Vaccines?
Yes. The vaccines are still relatively safe. However, if you have ever had Bell’s Palsy, ask your physician before receiving either of the mRNA vaccines. Bell’s Palsy is more likely to recur in persons who have had it before. [See Medscape.com]
** This article was corrected on 12/26/2020 so that the expected cases of BP in 100,000 vaccinated persons is 19 cases, not 113.8 cases. That is still 190 cases per million vaccinated.
Ronald L. Conte Jr.
“an author, not a doctor”