Dataset Information

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

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.

SUBMITTER: Sudjaritruk T

PROVIDER: S-EPMC9371339 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature

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Publications

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

Sudjaritruk Tavitiya T Kaewpoowat Quanhathai Q Prasarakee Chanidapa C Sarachai Saowalak S Taurel Anne-Frieda AF Sricharoen Natthanidnan N Assawawongprom Phatraporn P Saheng Jutamad J Harris Rebecca R Nealon Joshua J Yoksan Sutee S

PLoS neglected tropical diseases 20220801 8

<h4>Background</h4>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.<h4>Methods</h4>An age-stratified, population-based, seroepidemiological study was conducted in Chiang Mai, Thailand-a northern Thai pr ...[more]

PMID: 35913983

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Project description:BackgroundJapanese encephalitis (JE) virus is the leading cause of vaccine-preventable encephalitis and a significant cause of disability in Asia and the western Pacific. Many countries have introduced JE vaccination programs, including several low resource countries following WHO's prioritization of JE vaccination in 2006. We sought to characterize the public health impact of JE vaccination programs.Methodology/principal findingsJE case data and vaccination coverage rates, were requested from country health officials in 23 JE endemic countries and Chinese Taipei. Additional data were extracted from meeting presentations and published literature. JE incidence was compared before and after vaccination using a minimum three year period pre and post program introduction or expansion. Data suitable for analysis were available for 13 JE-endemic countries and Chinese Taipei, for either all age groups or for children aged under 15 years only. Five countries and Chinese Taipei introduced vaccine prior to 2006 and the all-age JE incidence was reduced by 73-100% in about 5-20 years following introduction. Six countries have introduced JE vaccine since 2006, and JE incidence in children aged younger than 15 years has been reduced by 14-79% as of 2015-2021. JE-specific data were unavailable before introduction in Thailand and Vietnam, but vaccination programs reduced acute encephalitis incidence by 80% and 74%, respectively. Even in the programs with greatest impact, it took several years to achieve their results.Conclusions/significanceJE vaccination has greatly reduced JE in 13 JE-endemic countries and Chinese Taipei. Highest impact has been observed in countries that introduced prior to 2006, but it often took roughly two decades and substantial resources to achieve that level of success. For greatest possible impact, more recently introducing countries and funding agencies should commit to continuous improvements in delivery systems to sustain coverage after initial vaccine introduction.

Dataset Information

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

Background

Methods

Results

Conclusions

Publications

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

Similar Datasets

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