Covid-19: Vaccine Carries Low Risk for Bell Palsy, Studies Suggest

Facial nerve palsy has been identified as a possible adverse effect of vaccination against Covid-19 with mRNA vaccines, but no such association was found in a newly published case-control study involving Bell palsy patients treated in emergency departments.

In the study from Israel, patients treated for Bell palsy in hospital emergency departments were matched to patients treated in the EDs for other reasons. The two groups had similar rates of vaccination against Covid-19.

In a separate review involving close to 350,000 patients with Covid-19 enrolled in a large, health research network database, having Covid-19 was linked to a greater risk for facial nerve palsy, but vaccination against the disease was not.

Findings from the two studies, both published online June 24 in JAMA Otolarygology-Head & Neck Surgery, add to the real-world data suggesting that Covid-19 vaccination does not significantly increase the risk for Bell palsy.

Data from the CDC’s Vaccine Safety Datalink involving more than 600,000 vaccinated individuals identified 21 cases of facial nerve palsy as of mid-February, which was comparable to the expected incidence among unvaccinated comparators.

A report from mid-May identified 1,743 cases of Bell palsy among 156 million vaccine recipients (270 million doses).

The newly published case-control study was conducted in January and February of this year at a single tertiary referral center in central Israel, and it included all patients admitted for facial nerve palsy during the period, matched by age, sex, and date of admission with control patients admitted for other reasons.

A total of 37 patients were admitted for facial nerve palsy during the two-month period (59.5% male, mean age 50.9 years).

The analysis revealed:

• Among recently vaccinated patients (21 [56.7%]), the mean (SD) time from vaccination to occurrence of palsy was 9.3 (4.2 [range, 3-14]) days from the first dose and 14.0 (12.6 [range, 1-23]) days from the second dose.
• Among 74 matched controls (2:1 ratio) with identical age, sex, and admittance date, a similar proportion were vaccinated recently (44 [59.5%]).
• The adjusted odds ratio for exposure was 0.84 (95% CI, 0.37-1.90; P=0.67). Analysis of the number of admissions for facial nerve palsy during the same period in preceding years (2015-2020) revealed a relatively stable trend (mean [SD], 26.8 [5.8]; median, 27.5 [range, 17-35]).

“No association between acute facial nerve palsy and recent vaccination with the BNT162b2 vaccine was observed,” wrote researcher Asaf Shemer, MD, of Shamir Medical Center, Tzrifin, Israel, and colleagues. “In addition, despite rapid and extensive vaccination of the population, a similar volume of admissions for facial palsy was seen compared with the same period in preceding years.”

The separate health network data review included a total of 348,088 patients with Covid-19, including 284 diagnosed with Bell palsy within 8 weeks of receiving an initial Covid diagnosis. A total of 153 (53.9%) had no history of Bell palsy, and 131 (46%) did have a history of the nerve disorder.

Among all patients with Covid-19, 1,525 (0.44%) had a history of Bell palsy before their Covid-19 diagnosis, which “translates to an 8.6% Bell palsy recurrence rate within 8 weeks of Covid-19 diagnosis,” wrote researcher Akina Tamaki, MD, of Cleveland Medical Center, and colleagues.

When the researchers matched patients with Covid-19 to people vaccinated against the disease (n=63,551), patients with active disease had a greater than 6-fold increased risk for Bell palsy compared to vaccinated individuals (relative risk, 6.8; 95% CI, 3.5-13.206; P<0.001).

The researchers noted that the annual incidence of Bell palsy is 15 to 30 cases per 100,000 people, with the recurrence rate among those with 1 prior episode of the disorder estimated to be around 8%.

“The present analysis found a higher incidence of Bell palsy in patients with Covid-19 (0.08%). This translates to approximately 82 per 100,000 patients with Covid-19,” they wrote. “The rate of recurrent Bell palsy in patients with previous history of Bell palsy at the time of Covid-19 diagnosis was 8.6%. This analysis found a statistically significant higher risk of Bell palsy in patients with Covid-19 compared with those who were vaccinated against the disease.”

In commentary published with the two studies, C.W. David Chang, MD, of the University of Missouri School of Medicine, wrote that the unavoidable short data collection window in both studies (3 months in the study by Tamaki et al and 2 months in the Shemer et al study) could have led to an under-reporting of Bell palsy.

“Not all patients likely would have 8 weeks of post-vaccination observation before data were analyzed for the studies,” Chang wrote. “Future analysis during a longer period of observation will be valuable.”

Chang wrote that while it will take time to collect the data and reduce confounding variables, the as yet unclear risk for Bell palsy pales in comparison with the case rate and death rate from Covid-19.

“While ascertaining the adverse event rate is important in seeking medical knowledge, socially our minds become confused by methodologic quibbling and statistical calculation regarding Bell palsy, sometimes distracting us from the real consequences of an uncontrolled pandemic,” Chang wrote.

“The already present danger of the ’known knowns’ of Covid-19 is overcome by the perseveration and anxiety of the ’known unknowns’ of the vaccines. Socially, our ability to appreciate and act on risk is in small part influenced by intellect and rationality, but in large part enacted by instinct and emotion. I hope that patients will continue to see their physicians as trusted sources. Our role as physicians is to distill these academic exercises into actionable guidance for patients.”

1. In a case-control study, patients treated for Bell palsy in hospital emergency departments were matched to patients treated in the EDs for other reasons. The two groups had similar rates of vaccination against Covid-19.

2. In a data review involving close to 350,000 patients with Covid-19 enrolled in a large, health research network database, having Covid-19 was linked to a greater risk for facial nerve palsy, but vaccination against the disease was not.

Salynn Boyles, Contributing Writer, BreakingMED™

Cat ID: 190

Topic ID: 79,190,730,933,190,926,192,927,151,928,925,934