The aim and design of this study
This study aims to explore the interlinks among the circulating EVs that demonstrate a long-term regular seasonality of prevalence. And whether the interactions are interfered by outer interventions such as NPIs of COVID-19. Therefore, seasonal ARIMA models were used to forecast the incidence of HFMD in order to analyze the potential impact of COVID-19 interventions on mitigating EV transmission. Spearman’s rank correlation was conducted for the major serotypes to figure out the potential VVIs.
Data collection
Nanchang, a city located at 115°27’-116°35’ E longitude and 28°10’-29°11’ N latitude (Figure 1). Nanchang had a population of 6.4 million as of 2022, accounting for 12.5% of the population of Jiangxi Province. Since June 2009, clinical specimens must be collected from all severe HFMD cases, and the first 5 mild cases reported per month in each county or district are tested for enteroviruses using real time RT-PCR by the local CDCs (1, 15).
During 2019-2022, a total of 2296 clinically diagnosed HFMD cases were collected from 9 hospitals in Nanchang, including Jiangxi Provincial Children’s Hospital and 8 county and district sentinel hospitals. A total of 2296 clinical specimens (1737 pharyngeal/throat swabs, 381 anal swabs and 178 stools) were collected.
The study was approved by the ethics committee of the Nanchang Center for Disease Control and Prevention, and the procedures were performed according to the approved guidelines (Approval No. NCCDC-20100701). Prior informed consent was obtained from patients or their parents for sample collection.