Impact of the COVID-19 pandemic on telogen effluvium: a nationwide multicentre interrupted time series study.

Background: There is ongoing debate regarding the association between telogen effluvium (TE) and COVID-19, as well as COVID-19 vaccines.

Objectives: To investigate the impact of the COVID-19 pandemic and vaccination on the development of TE among patients visiting dermatology clinics in South Korea.

Methods: Between 2017 and 2022, data regarding patients with TE and other types of hair loss were collected from 22 hospitals in South Korea. An interrupted time series analysis was conducted, dividing the time into periods before and after the COVID-19 pandemic, as well as before and after the COVID-19 vaccination.

Results: There was a significant slope change in the percentage of cases of TE during the postpandemic period (slope change 0.011, 95% confidence interval 0.005-0.017, P < 0.001), but no significant changes were observed after vaccination. The percentage of patients with other types of hair loss was not associated with COVID-19 or vaccination. The retrospective nature of the study may have limited the ability to establish causation.

Conclusions: This multicentre study provides insights into the epidemiology of TE, showing a significant increase in cases of TE following the COVID-19 pandemic. However, there was no association between the occurrence of TE and COVID-19 vaccines.