HAND, FOOT AND MOUTH DISEASE IN SOUTHERN VIETNAM DURING 2015 – 2021

Abstract

Intro: Hand, foot and mouth disease (HFMD) continues to challenge Asia with pandemic potential. In Vietnam, there have been two major outbreaks occurring during 2011–2012 (>200,000 hospitalizations and >200 deaths) and more recently in 2018 (>130,000 hospitalizations and 17 deaths). Given the high burden and the complex epidemic dynamics of HFMD, synthesizing its clinical and epidemiological data remains essential to develop appropriate interventions and apply public health measures. Methods: From 2015-2021, clinical samples were collected from patients enrolled in a HFMD study conducted at three referral hospitals in Ho Chi Minh City, Vietnam. Enterovirus diagnosis and serotypes determination was carried out using a combination of PCR and sequencing approaches. All EV-A71 positive cases were then subtyped by Sanger sequencing and/or whole-genome sequenced using next-generation based approach Findings: A total of 19 enterovirus serotypes were detected in 1660 HFMD patients enrolled in the study during 2015–2021. EV-A71 (26.2%, n=435) remains the leading cause of HFMD in Vietnam, followed by coxsackievirus A6 (CV-A6, 17.8%, n=296), CV-A16 (11%, n=184) and CV-A10 (7.1%, n=118). There are two main EV-A71 subgenogroups, C4 and B5, and their prevalence interchanges over the years. EV-A71 C4 displayed low activity during 2015 – early 2018 and then emerged in late 2018, early 2019 and late 2020. Compared with B5, C4 was more likely to be associated with severe HFMD. During the study period, the proportion of CV-A6 and CV-A16 increased in 2017 followed by a drop in 2018, and then went up again between 2019 and 2021 Conclusion: Our data have provided significant insights into important aspects of HFMD over seven years (2015–2021) in Vietnam, and emphasize active surveillance for pathogen circulation remains essential to inform the local public health authorities in the development of appropriate intervention strategies to reduce the burden of this disease. Multivalent vaccines are urgently needed to control HFMD