Key result
Vietnamese Coxsackievirus A16 strains belong to a single genogroup B1a that has been circulating in Southern Vietnam since 2011, displaying stable genetic diversity without frequent subgenogroup replacement.
Why the study?
There had been no report regarding the epidemiology and genetic diversity of CVA16 in Vietnam, which is critical to inform intervention strategies.
Observational (n=320)
Yes
CVA16 is an endemic HFMD pathogen in southern Vietnam with a single subgenogroup B1a circulating since 2011, highlighting the need for active viral surveillance to inform outbreak response and vaccine development.
Informs regional enterovirus surveillance; leaves open any cardiac complication implications.
Background: Hand, Foot and Mouth Disease (HFMD) is a major public health concern in the Asia-Pacific region. Most recent HFMD outbreaks have been caused by enterovirus A71 (EV-A71), coxsackievirus A16 (CVA16), CVA10, and CVA6. There has been no report regarding the epidemiology and genetic diversity of CVA16 in Vietnam. Such knowledge is critical to inform the development of intervention strategies. Materials and Methods: From 2011 to 2017, clinical samples were collected from in- and outpatients enrolled in a HFMD research program conducted at three referral hospitals in Ho Chi Minh City (HCMC), Vietnam. Throat or rectal swabs positive for CVA16 with sufficient viral load were selected for whole genome sequencing and evolutionary analysis. Results: Throughout the study period, 320 CVA16 positive samples were collected from 2808 HFMD patients (11.4%). 59.4% of patients were male. The median age was 20.8 months (IQR, 14.96–31.41). Patients resided in HCMC (55.3%), Mekong Delta (22.2%), and South East Vietnam (22.5%). 10% of CVA16 infected patients had moderately severe or severe HFMD. CVA16 positive samples from 153 patients were selected for whole genome sequencing, and 66 complete genomes were obtained. Phylogenetic analysis demonstrated that Vietnamese CVA16 strains belong to a single genogroup B1a that clusters together with isolates from China, Japan, Thailand, Malaysia, France and Australia. The CVA16 strains of the present study were circulating in Vietnam some 4 years prior to its detection in HFMD cases. Conclusion: We report for the first time on the molecular epidemiology of CVA16 in Vietnam. Unlike EV-A71, which showed frequent replacement between subgenogroups B5 and C4 every 2–3 years in Vietnam, CVA16 displays a less pronounced genetic alternation with only subgenogroup B1a circulating in Vietnam since 2011. Our collective findings emphasize the importance of active surveillance for viral circulation in HFMD endemic countries, critical to informing outbreak response and vaccine development.
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Nhu et al. (2021) conducted an observational in Hand, Foot and Mouth Disease (HFMD) (n=320). Coxsackievirus A16 infection was evaluated on Molecular epidemiology and genetic diversity of CVA16. Vietnamese Coxsackievirus A16 strains belong to a single genogroup B1a that has been circulating in Southern Vietnam since 2011, displaying stable genetic diversity without frequent subgenogroup replacement.
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