Bell Palsy Risk May Be Higher in Individuals With COVID-19 History

Compared with individuals who completed their COVID-19 vaccination, the risk for COVID-19-related Bell’s palsy was higher among those who did not complete the primary series of the vaccine.

Regardless of vaccination status, patients who contract COVID-19 may have an increased risk of developing Bell’s palsy, according to study findings published in the journal Clinical Microbiology and Infection.

Previous research has shown that viral infections can contribute to the development of Bell’s palsy, which manifests as paralysis on one side. Researchers conducted a cohort study to assess the relationship between SARS-CoV-2 infection and the development of Bell’s palsy. 

The researchers collected data from the Korea Disease Control and Prevention Agency (KDCA) and the Korea National Health Insurance Service (NHIS). A total of 52,883,804 participants with and without COVID-19 were included in this study, with an average Bell’s palsy onset of 109.8 days.

After exclusion, a total of 36,565,099 participants without COVID-19 and 11,593,365 participants with COVID-19 remained for the analysis. The health screening included 12,972,906 participants without COVID-19 and 4,001,332 participants with COVID-19.

Future biological experiments are needed to elucidate the underlying mechanisms and provide a comprehensive understanding of the relationship between COVID-19 and BP.

Bell’s palsy was diagnosed according the International Classification of Diseases 10th revision (ICD-10) codes and based on glucocorticoid use. 

The researchers classified participants younger than age 60 with no comorbidities and immune suppression as mild-low risk. Those who were age 60 and older with comorbidities or with COVID-19 medications without additional ventilation assistance were in the mild-high risk group. 

Patients were considered at serious risk if they were prescribed COVID-19 medications and did not require ventilation assistance. Hospitalized patients in the intensive care unit, in isolation, or prescribed COVID-19 medications and required ventilation assistance were defined as the severely serious group.

Among patients in the health screening cohort, participants with COVID-19 had a greater likelihood of being younger, being women, having a lower household income, and were less likely to have their COVID-19 vaccination.

The researchers reported an increased risk for incident Bell’s palsy among patients with COVID-19 who received a vaccine (adjusted subdistribution hazard ratio [aSHR], 1.20; 95% CI, 1.15-1.25) and those who were unvaccinated (aSHR, 1.84; 95% CI, 1.59-2.12). 

While both groups had an increased risk for Bell’s palsy, unvaccinated individuals had a higher risk of developing Bell’s palsy compared with those who completed 1 dose of the COVID-19 vaccine (P <.001). Additionally, unvaccinated individuals had an increased risk for incident Bell’s palsy following SARS-CoV-2 (aSHR, 1.47; 95% CI, 1.11-1.94; P =.015)

There was an increasing risk for Bell’s palsy based on COVID-19 severity (P =.001), with the highest risk for incident Bell’s palsy observed among unvaccinated patients with serious to severely serious COVID-19 (aSHR, 2.40; 95% CI, 1.37-4.21). 

“Future biological experiments are needed to elucidate the underlying mechanisms and provide a comprehensive understanding of the relationship between COVID-19 and BP [Bell’s palsy],” the researchers noted.

Study limitations are the potential delay in COVID-19 diagnoses in South Korea, the exclusion of participants with Bell’s palsy-related conditions, and data representing pre-omicron variant COVID-19 phases. 

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

This article originally appeared on Neurology Advisor


Kim HJ, Jeong S, Song J, et al. Risk of Bell’s palsy following SARS-CoV-2 infection: a nationwide cohort study. Clin Microbiol Infect. Published online August 21, 2023. doi:10.1016/j.cmi.2023.08.014