Abstract:

Objective To analyze the epidemiological characteristics of coxsackievirus A16 (CVA16)-associated hand, foot and mouth disease (HFMD) in China for evidences to inform targeted prevention and control strategies and measures. Methods Virological surveillance data on HFMD were retrieved from 31 provincial-level administrative divisions (provinces, autonomous regions, and municipalities) in China between 2010 and 2022. Descriptive epidemiology was used to analyze the epidemiological characteristics of CVA16-associated HFMD cases identified through the national surveillance network. Results From 2010 to 2022, virological surveillance of HFMD in China recorded 1 150 953 cases, in whom 755 660 were laboratory-confirmed positives, with an overall positivity rate being 65.66%. There were 71 748 severe (including fatal) cases, among which 54 304 were positive, with a positive detection rate of 75.69%. No significant trend was observed in the annual proportion of CVA16 among positive cases (χ²_trend=0.01, P>0.05). In contrast, EV-A71 showed a significant decline (χ²_trend=113 262.42, P<0.01), whereas other enteroviruses exhibited an upward trend (χ²_trend=81 714.46, P<0.01). The overall CVA16 detection rate was 17.05% (196 273/1 150 953), in which positive detection rate was 6.03% (4 324/71 748) for severe cases (including deaths). The positive rate of CVA16 was the lowest (4.47% on average yearly) in 2010-2015 in severe cases (including deaths), and increased to 11.56% on average between 2016 and 2022. By temporal distribution, CVA16-associated HFMD displayed a unimodal seasonal pattern, peaking annually from March to July, with southern regions experiencing earlier outbreaks than northern areas. By population distribution, males and females accounted for 61.21% (120 129/196 273) and 38.79% (76 144/196 273) of the CVA16 cases, with detection rates of 17.20% and 16.82%, respectively (χ²=29.29, P<0.01). The infection was dominated in children aged 0-5 years (91.63%, 179 837/196 273). Provincial variation in CVA16 detection was minimal among mild cases but substantial for severe/fatal cases. Conclusion In China, the proportional contribution of CVA16 and its overall positive detection rate among HFMD cases remained stable. However, a significant increase in positive detection rates was observed specifically in severe cases. These findings highlight the necessity for sustained virological surveillance of HFMD pathogens, continuous monitoring of CVA16 transmission dynamics, strengthened prevention and control measures in high-incidence regions and high-risk populations, and expedited development of multivalent vaccines incorporating CVA16.

Key words: Hand, foot and mouth disease, Coxsackievirus A16, Epidemiological characteristics, Pathogenic surveillance