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. 2021 Jul 6;9(7):746.
doi: 10.3390/vaccines9070746.

Association between Influenza Vaccination and the Risk of Bell's Palsy in the Korean Elderly

Nayoung Jeong  1 , Yejee Kim  2 , Chungjong Kim  3 , Sangmin Park  4   5 , Joongyub Lee  6 , Namkyong Choi  1
Affiliations

Association between Influenza Vaccination and the Risk of Bell's Palsy in the Korean Elderly

Nayoung Jeong et al. Vaccines (Basel). .

Abstract

Previous studies have shown controversial results on the risk of Bell's palsy after influenza vaccination. Since the antigenic components of influenza vaccine can vary from season to season, continuous safety monitoring is required. The aim of the present study was to determine whether there was an increased risk of Bell's palsy in the elderly after influenza vaccination between the 2015/2016 and 2017/2018 flu seasons. This study included the elderly who received influenza vaccinations for three flu seasons using a large-linked database of vaccination registration data from the Korea Disease Control and Prevention Agency and the National Health Insurance Service claims data. We used a self-controlled risk interval design with a risk interval of 1 to 42 days and a control interval of 57 to 98 days postvaccination and calculated the incidence rate ratio. To ensure the robustness of the results, sensitivity analyses were also carried out with different risk and control intervals. Of 4,653,440 elderly people who received the influenza vaccine, there was no statistically significant increase in the risk of Bell's palsy (IRR: 0.99, 95% CI: 0.92-1.07). Similar results were found in analysis results for each season and the results of the sensitivity analyses excluding the 2017/2018 season. In conclusion, we found no evidence of an increased risk of Bell's palsy after influenza vaccination. The results of our study provide reassurance about the safety of the influenza vaccine NIP program. However, it is necessary to continuously monitor the risk of Bell's palsy during future flu seasons.

Keywords: Bell’s palsy; adverse events; elderly people; influenza vaccine; large-linked database; self-controlled risk interval design.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Illustration of risk and control intervals for self-controlled risk interval analysis.
Figure 2
Figure 2
Distribution of influenza vaccination in the elderly during three flu seasons, 2015/2016 season through 2017/2018 season.
Figure 3
Figure 3
Distribution of the occurrence of Bell’s palsy 1–98 days following influenza vaccination, 2015/2016 season through 2017/2018 season. The graphs illustrate timing during (A) the 2015/2016 through 2017/2018 seasons, (B) the 2015/2016 season, (C) the 2016/2017 season, (D) the 2017/2018 season.
Figure 4
Figure 4
Subgroup analysis for the risk of Bell’s palsy after influenza vaccination.
See this image and copyright information in PMC

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