The impact of COVID-19 pandemic on reported notifiable infectious diseases in China: An interrupted time series analysis.

Background: During major public health crises, the epidemiological characteristics of commonly reported infectious diseases may change. Based on routinely reported data on notifiable infectious diseases, we investigated whether the incidence and mortality of infectious diseases in China were affected by the coronavirus disease (COVID-19).

Methods: We analyzed monthly reported data on nationally notifiable infectious diseases from January 2013 to March 2024. Using an interrupted time series design, we performed Poisson regression to assess changes in the incidence and mortality rates of infectious diseases before, during, and after the COVID-19 pandemic.

Results: We found that during the COVID-19 outbreak, the reported incidence of nationally notifiable infectious diseases significantly and immediately decreased (relative risk [RR]= 0.6206; 95% confidence interval [CI]= 0.6201-0.6211), and so did the mortality rate (RR=0.7814; 95% CI=0.7696-0.7933). After the end of pandemic control measures, the reported incidence surged abruptly starting from January 2023, showing a sharp rise compared with the prepandemic period (RR=1.8608; 95% CI=1.8595-1.8621). The reported mortality increased, too (RR=1.081; 95% CI=1.0638-1.0984).

Conclusions: The overall incidence and mortality of infectious diseases decreased immediately after the outbreak of COVID-19. After the end of pandemic control measures, their incidence rate sharply increased, and their mortality rate also rose.