[Epidemiological characteristics and optimization of prevention and control strategies for norovirus gastroenteritis outbreaks in schools of Haidian District, Beijing, 2021-2023].

Objective

To analyze the epidemiological characteristics of norovirus gastroenteritis outbreaks in schools of Haidian District, Beijing, from 2021 to 2023, and providing a scientific basis for optimizing prevention and control strategies for future outbreaks.

Methods

The reported data on school norovirus gastroenteritis outbreaks were handled and collected by the Haidian District CDC of Beijing from January 2021 to December 2023. The outbreak scale is classified as clustered outbreaks and outbreak events. The norovirus RNA was detected by the RT-PCR method. Descriptive epidemiological methods were used to analyze the epidemiological characteristics of outbreaks of different scales. Univariate analysis was conducted using the χ2 test and/or Fisher's exact probability method, and multivariate analysis was performed using the Firth biased likelihood regression model to analyze the related factors of the school outbreak scale. Statistical analysis was carried out using SPSS 26.0 software and R 4.2.3 software.

Results

From 2021 to 2023, there were 57 outbreaks of norovirus gastroenteritis in schools in Haidian District, Beijing, involving 777 cases. Among them, there were seven outbreaks (12.28%, 7/57), with 359 cases (46.20%, 359/777). The scale of the outbreaks involved cases in the M (Q1, Q3) range of 34 (26, 64). The outbreaks showed a distinct seasonal distribution pattern, occurring only in March to April and September to October. March was the peak month, and the number of outbreaks and the peak number of cases (in March and September) occurred earlier than the peak of clustered outbreaks (in April and October). In the outbreaks, universities were the high-risk locations, with the number of outbreaks and cases accounting for 57.14% (4/7) and 79.39% (285/359), respectively. In clustered outbreaks, kindergartens were the high-risk locations, with the number of outbreaks and cases accounting for 58.00% (29/50) and 56.46% (236/418), respectively. The incidence rate of outbreaks in universities (10.81%) was higher than that in other types of schools. The results of the multivariate Firth likelihood regression model showed that the failure to early detect cases was a positive correlation factor for the occurrence risk of outbreaks, and the risk of occurrence was 9.09 times (95%CI: 1.02-108.76) higher than that of early case detection.

Conclusions

The high-risk locations for norovirus gastroenteritis outbreaks were universities in Haidian District, Beijing, from 2021 to 2023. The period from 1 to 2 months after the start of the school term was a critical juncture. The failure to detect cases early was a key factor leading to the delayed response and expansion of the outbreak. To further optimize prevention and control strategies, it is recommended to develop a university-specific plan tailored to the characteristics, establish and improve a multi-point monitoring and early warning system, and strengthen the hierarchical response mechanism, environmental disinfection, and precise suspension of classes/staffing measures.