Seroprevalence of measles and varicella in healthcare workers in Chonburi province, Thailand between October 2022 and January 2023

Introduction Health care workers (HCWs) face the risk of contracting and transmitting vaccine-preventable infectious diseases (VPDs). Therefore, it is crucial to evaluate the immune status of HCWs against certain VPDs, such as measles and varicella zoster virus (VZV). This study aimed to determine age-specific seropositivity rates of anti-measles and anti-VZV IgG in HCWs working in Chonburi province, Thailand, and to develop a measles and varicella vaccination policy for Thai HCWs. Methods A total of 266 HCWs in Chonburi Province, Thailand, were enrolled in this study between October 2022 and January 2023. Participants were divided into six age groups: 21-30, 31-40, 41-50, 51-60, 61-70, and >70 years. Anti-measles and anti-VZV IgG levels were evaluated using commercial ELISA kits (EUROIMMUN, Lübeck, Germany). Results The overall seropositivity rates for measles and varicella were 85.0% and 81.2%, respectively. The lowest seropositivity rates for both measles and varicella were found among the 21-30-year-old group. Furthermore, seropositivity rates increased with age, reaching 100% among people over the age of 60 years. Conclusions To prevent measles and VZV outbreaks in HCWs, it is crucial to implement catch-up measles and varicella vaccination programs, particularly among HCWs younger than 30 years of age. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was financially supported by the Health Systems Research Institute (HSRI), the National Research Council of Thailand (NRCT), the Research Chair Grant from the National Science and Technology Development Agency (P-15-50004), the Center of Excellence in Clinical Virology, Chulalongkorn University, and King Chulalongkorn Memorial Hospital and the Second Century Fund (C2F) of Jira Chansaenroj, Chulalongkorn University. The funders had no role in study design, data collection, analysis, publication decision, or manuscript preparation. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Institutional Review Board (IRB), Faculty of Medicine, Chulalongkorn University (IRB No.0706/65) and The Institutional Review Board of Chonburi Provincial Public Health Office, Ministry of Public Health (IRB No. 0024-2565), Thailand gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The authors confirm that all data supporting the findings of this study are available within the article.