Abstract
BACKGROUND: The implementation of COVID-19 control and prevention measures has significantly influenced the incidence rates of multiple notifiable infectious diseases. We aimed to investigate the epidemiological trends of notifiable infectious diseases in mainland China from 2020 to 2024, a period spanning both stringent interventions and their subsequent relaxation. METHODS: We systematically analysed surveillance data from the National Center for Disease Control and Prevention (2020-2024). We excluded COVID-19, monkeypox, and neonatal tetanus to ensure methodological consistency and comparability. We classified the diseases into Class A, B, and C notifiable infectious diseases and further grouped them by transmission routes: intestinal, respiratory, sexually transmitted and blood-borne, vector-borne/zoonotic, and others. We focused on incidence rates, mortality rates, seasonal patterns, and trends to inform future prevention and control strategies. RESULTS: Between 2020 and 2024, mainland China recorded 38 notifiable infectious diseases (excluding COVID-19, monkeypox, and neonatal tetanus). The average incidence rate was 734.8945/100 000, showing an upward trend. Class A notifiable infectious diseases were extremely rare, Class B encompassed 25 types and showed a rising trend with minimal seasonal variation, and Class C included 11 types. Class C notifiable infectious diseases incidence remained relatively low from 2020 to 2022, but rose sharply in 2023 after the relaxation of COVID-19 restrictions, maintaining elevated levels in 2024, with pronounced winter/spring peaks observed, especially in 2023-2024. Respiratory infectious diseases (RIDs) exhibited the highest incidence, while blood-borne and sexually transmitted infectious diseases accounted for over 90.35% of the deaths. CONCLUSIONS: In mainland China, strict COVID-19 measures between 2020 and 2022 significantly reduced the incidence of RIDs. However, after COVID-19 management was downgraded and restrictions were relaxed in early 2023, these diseases resurged, demonstrating a 'suppression-rebound' effect.