Trend of immunity against measles and varicella zoster virus in healthcare workers in Korea.

• A seroprevalence study and survey in healthcare workers (HCWs) were conducted in a tertiary care hospital from 2017 to 2022. • Measles seropositivity declined gradually from >90 % in the HCWs born in the 1960s to <80 % in those born in the 1990s. • The seropositivity for VZV was stable at >90 %. • The self-reported history was not sufficiently reliable for screening HCWs. To examine the seroprevalence of measles and varicella zoster virus (VZV) among healthcare workers (HCW) and evaluate the concordance between self-reported history of previous disease or vaccination and seropositivity. A seroprevalence study and survey. A university-affiliated tertiary care hospital. All HCWs working in high-risk services in 2017 underwent serologic tests and survey; all new HCWs employed in the subsequent years, serologic tests only. A serologic study was conducted using chemiluminescence immunoassay (2017) or enzyme immunoassays (2018 and later). HCWs who underwent serological testing in 2017 completed a self-administered questionnaire on their history of infection and vaccination. A total of 10,278 and 9607 HCWs underwent serologic tests for measles and VZV IgG, respectively, from 2017 to 2022. The overall seropositivity rates for measles and VZV were 78.1 % and 92.8 %, respectively. Measles seropositivity declined gradually from >90 % in the HCWs born in the 1960s to <80 % in those born in the 1990s. There was a significant difference in measles seropositivity between the birth cohorts (BCs) 1967–1984 and 1985–1999 (P < 0.001; odds ratio, 1.16; 95 % confidence interval, 1.14–1.18). The seropositivity for VZV was stable, at >90 % in all BCs. The self-reported vaccination history was not independently associated with seropositivity, and the negative predictive value of the survey was very low (9.6 % and 13.1 %, respectively). Measles seropositivity showed a substantial decline among HCWs born in 1985 or later, while varicella seropositivity remained high. The self-reported vaccination history was not sufficiently reliable for screening HCWs. [ABSTRACT FROM AUTHOR]