Effect of universal varicella vaccination and behavioral changes against coronavirus disease 2019 pandemic on the incidence of herpes zoster.

BACKGROUND: Since 2014, universal varicella vaccination has reduced the varicella and herpes zoster (HZ) incidence in vaccine recipients and increased the incidence in the child-rearing generation until 2017. OBJECTIVE: This study aimed to understand the future epidemiologic trends of HZ after the disappearance of varicella epidemics and during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: The Miyazaki Dermatologist Society has been monitoring and analyzing the incidence of HZ patients after universal vaccination since 1997. RESULTS: The HZ incidence in Oka varicella vaccine recipients aged 0-4 years decreased with the reduction in chickenpox incidence. The HZ incidence among those aged 5-9 years increased between 2015 and 2017 and decreased thereafter. From 2014-2020, the HZ incidence continued to increase to 36.6%, 51.3%, 70.2%, 56.7%, and 27.3% among those aged 10-19, 20-29, 30-39, 40-49, and 50-59 years, respectively. The HZ incidence in patients aged ≥ 60 years increased by 2.3% annually from 2014 to 2020, corresponding to an annual 2% increase since 1997, and was unaffected by varicella epidemics. COVID-19 infection control measures, lifestyle changes and the resulting stress did not affect the HZ incidence in 2020. CONCLUSION: Universal varicella vaccination eliminated varicella epidemics, and HZ was reduced in vaccine recipients. The HZ incidence for those aged 10-59 years increased from 2014 to 2020, in contrast to those aged ≥ 60 years, which is attributable to booster immunity expiration due to varicella contact in this age group.