Impact of the COVID-19 Pandemic and Vaccination on Bell's Palsy: A Retrospective Comprehensive Analysis Using TriNetX Data.

Background: Bell's palsy (BP), a sudden onset of facial paralysis, has been reported in patients with COVID-19. The relationship between COVID-19 infection and BP remains unclear, as does the impact of COVID-19 vaccination on its incidence. This study aims to assess the occurrence of BP before and after the COVID-19 pandemic and to explore any potential effects of COVID-19 vaccination on BP cases.

Methods: This study utilized data from the TriNetX global health research network, specifically the US Collaborative Network of 68 healthcare organizations, encompassing 99,852,106 patients with ICD codes from 2016 to 2024. BP cases were identified using ICD-10 code G51.0, while COVID-19 vaccinations and infections were identified using CPT codes and TNX Curated 9088, respectively. We conducted an incidence and prevalence analysis of BP cases annually over the 8-year period to detect trends and compared BP rates between prepandemic (2016-2020) and postpandemic (2020-2024) periods using odds ratios. Additionally, we assessed BP incidence among COVID-19 patients and performed a subgroup analysis on vaccinated individuals to evaluate the impact of vaccination on BP incidence. To reduce potential confounding, we employed propensity score matching using the greedy nearest neighbor method available in the TriNetX platform, matching patients on age, sex, race, type 2 diabetes mellitus, and vascular commodities. Statistical analyses were executed within the TriNetX platform and supplemented by online AI tools using Python.

Results: The analysis of BP cases from 2016 to 2024 revealed an upward trend in both incidence and prevalence. The incidence proportion rose from 48 cases per 100,000 people in 2016-2017 to 69 cases per 100,000 by 2023-2024, with a significant increase noted from 2021 onwards. Similarly, the incidence rate increased from 0.00000155 to 0.00000333 over the same period. Prevalence also showed a steady rise, from 228 to 434 cases per 100,000 people. Trend analyses confirmed these increases as statistically significant, with p-values indicating upward trends in incidence and prevalence. Comparing prepandemic (2016-2020) to postpandemic (2020-2024) periods, there was a significant rise in incidence proportions (p-value ≈ 0.0074) and prevalence rates (p-value = 0.0180). Among COVID-positive patients, the incidence proportion remained stable, while prevalence increased, indicating a higher burden compared to the general population. After propensity score matching, vaccinated individuals exhibited a significantly lower risk of BP compared to unvaccinated individuals (hazard ratio: 0.723, 95% CI: 0.618-0.84, p < 0.001).

Conclusion: This highlights a significant increase in the incidence and prevalence of BP during the COVID-19 pandemic years compared to prepandemic levels. While the incidence of BP among vaccinated individuals showed a gradual increase, when mitigating for confounding influences using propensity score-matched analyses, it is revealed that these rates remained significantly lower than in unvaccinated populations, indicating a potentially protective association with vaccination. Changes in lifestyle, stress, and distribution of environmental viral loads and potentials during the pandemic may have contributed to a higher susceptibility to BP in the general population.