Seroepidemiological study of Japanese encephalitis virus in Chiang Mai: Immunity and susceptibility 28 years after introduction of a vaccination programme

Tavitiya Sudjaritruk; Quanhathai Kaewpoowat; Chanidapa Prasarakee; Saowalak Sarachai; Anne-Frieda Taurel; Natthanidnan Sricharoen; Phatraporn Assawawongprom; Jutamad Saheng; Rebecca Harris; Joshua Nealon; Sutee Yoksan

doi:10.1371/journal.pntd.0010674

Seroepidemiological study of Japanese encephalitis virus in Chiang Mai: Immunity and susceptibility 28 years after introduction of a vaccination programme

PLoS Negl Trop Dis. 2022 Aug 1;16(8):e0010674. doi: 10.1371/journal.pntd.0010674. eCollection 2022 Aug.

Authors

Affiliations

¹ Department of Pediatrics, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
² Clinical and Molecular Epidemiology of Emerging and Re-emerging Infectious Diseases Research Cluster, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
³ Research Institute for Health Sciences, Chiang Mai University, Chiang Mai, Thailand.
⁴ Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
⁵ Vaccine Epidemiology and Modeling Department, Sanofi, Singapore.
⁶ Medical Department, Sanofi, Bangkok, Thailand.
⁷ Center for Vaccine Development, Institute of Molecular Biosciences, Mahidol University, Bangkok, Thailand.
⁸ Chulabhorn Research Institute, Bangkok, Thailand.

Abstract

Background: Thailand has introduced a nationwide vaccination against Japanese encephalitis virus (JEV) into National Immunization Programme since the 1990's. To improve the understanding of immunity and susceptibility of the population after 28 years of a vaccination programme, we conducted a JEV seroepidemiological study in a JEV-endemic area of Thailand.

Methods: An age-stratified, population-based, seroepidemiological study was conducted in Chiang Mai, Thailand-a northern Thai province where is an endemic area of Japanese encephalitis. Nine districts were chosen based on administrative definition: rural (n = 3); urban (n = 3); and peri-urban (n = 3). Within each district, eligible participants were randomly selected from 3 age groups: adolescents (10-20 years); adults (21-50 years); and older adults/elderly (≥51 years) by computer randomization. Plaque reduction neutralization tests (PRNT50 and PRNT90) were performed to measure neutralizing antibodies to JEV. To account for the cross-reactivity of JEV and other flaviviruses, JEV seroprotection was defined according to age, previous history of JEV vaccination, and PRNT50/PRNT90 levels of study participants.

Results: Overall, 279 adolescents, 297 adults, and 297 older adults/elderly were enrolled from nine districts. Age-stratified, protocol-defined, cluster-adjusted JEV seroprotection rates were 61% (95% CI: 48-73%), 43% (95% CI: 31-57%), and 52% (95% CI: 37-67%) for adolescents, adults, and older adults/elderly, respectively. Living in peri-urban districts, having a history of prior dengue virus infection, and previously receiving mouse brain-derived JEV vaccine were significantly associated with seroprotection to JEV in adolescents. Older age and male sex were associated with seroprotection for adults; and only male sex was the associated factor for older adults/elderly (P <0.05).

Conclusions: Approximately half of population living in a JEV-endemic area demonstrated seroprotection to JEV. Ongoing nationwide surveillance on JEV seropepidemiology is an important strategy to understand the evolving population-level immunity to JEV, and to help formulating the appropriate recommendations on JE immunization.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antibodies, Neutralizing
Antibodies, Viral
Encephalitis Virus, Japanese*
Encephalitis, Japanese* / epidemiology
Encephalitis, Japanese* / prevention & control
Humans
Japanese Encephalitis Vaccines*
Male
Mice
Seroepidemiologic Studies
Vaccination

Substances

Antibodies, Neutralizing
Antibodies, Viral
Japanese Encephalitis Vaccines

Grants and funding

This collaborative study was supported by Sanofi [Grant number: JEC00030]. T.S. is an author who received the fund. Sanofi authors contributed to development of the study protocol, analysis plan and the final manuscript. Sanofi authors had no role in data collection, analysis, and interpretation. Final decisions on study conduct, manuscript content, and journal submission were made by the Principal Investigator (T.S.). Sanofi URL: https://www.sanofi.com/en/your-health/vaccines.