Seroprevalence of EV-A71 neutralizing antibodies following the 2011 epidemic in HCMC, Vietnam

Abstract

Enterovirus-A71 (EV-A71) cyclically causes hand-foot-mouth disease (HFMD) epidemics in Asian children. An EV-A71 epidemic occurred in Southern Vietnam in 2011, but its scale is not clear. We collected residual sera from non-HFMD Vietnamese inpatients in 2012-2013 to determine seroprevalence of EV-A71 neutralizing antibodies, and measured cross-reactive neutralizing antibody titers against three EV-A71 genogroups. About 23.5% of 1-yearold children in Southern Vietnam has been infected by EV-A71, and the median age of infection was estimated to be 3 years. No significant antigenic variation could be detected among the three EV-A71 genogroups. The high seroprevalence of EV-A71 neutralizing antibody in children living in southern Vietnam indicates the necessity of introducing EV-A71 vaccines in southern Vietnam, particularly for children under 6 months of age. Moreover, it is critical to understand EV-A71 disease burden for formulating national vaccination policy. Author summaryEnterovirus-A71 (EV-A71), a member of the enterovirus genus, is a virulent pathogen causing neurological complications. EV-A71 mainly spreads through oral-fecal or oraloral transmission, as well as respiratory droplets. EV-A71 outbreaks have cyclically occurred throughout some Asian countries since 1997, with millions of people affected. The presence of serum neutralizing antibodies to EV-A71 can represent the prevalence of previous EV-A71 infections and seroprevalence studies are widely used to understand prevalence of infectious diseases. The results of our study demonstrate that about 50% of young children under 3 years of age were infected during the 2011 epidemic in southern Vietnam. The high seroprevalence of EV-A71 neutralizing antibody in children living in southern Vietnam indicates the necessity of introducing EV-A71 vaccines, particularly for children under 6 months of age. Moreover, it is critical to understand EV-A71 disease burden for formulating national vaccination policy in the future. PLOS NEGLECTED TROPICAL DISEASESPLOS Neglected Tropical Diseases | https://doi.

Age-time-specific transmission of hand-foot-and-mouth disease enterovirus serotypes in Vietnam: A catalytic model with maternal immunity

“…In recent years, HFMD case data in Vietnam has been used to analyse HFMD symptom variation across different infected serotypes, the phylogenic patterns of emerging cases, frequency of cases infected by different virus serotypes, and the association between disease outbreaks and climate factors ( Van Hoang et al, 2019 , Thanh Nhan et al, 2020 , Hoa-Tran et al, 2020 , Nguyen et al, 2020 ). Serological survey data of HFMD in Vietnam has been used to analyse seroprevalence of EV-A71 and maternal immunity ( Nguyen Tran et al, 2011 , Kuo et al, 2020 ). Despite the differences between case data and serological survey data, both can provide information about the transmission patterns of HFMD viruses.…”