JMIR Publications

ABSTRACT

Background:

Beyond the direct effect of COVID-19 infection in young people, the wider impact of the pandemic on other infectious diseases is unknown.

Objective:

This study aimed to assess changes in the incidence and mortality of 42 notifiable infectious diseases during the pandemic among children and adolescents in China, compared to pre-pandemic levels.

Methods:

China's Notifiable Infectious Disease Surveillance System was used to identify incident cases and deaths in 5-22-year-olds across 42 notifiable infectious diseases from 2018 to 2021. These infectious diseases were categorized into five groups: respiratory, gastrointestinal and enterovirus, sexually transmitted and blood-borne, zoonotic, and vectorborne diseases. Each year (2018-2021) was segmented into four phases: phase I (Jan 1-Jan 22), phase II (Jan 23-Apr 7), phase III (Apr 8-Aug 31), and phase IV (Sep 1-Dec 31) according to the varying intensities of pandemic restrictive measures in 2020. Generalized linear models were applied to assess the change in incidence and mortality within each disease category, using 2018 and 2019 as the reference.

Results:

A total of 4,898,260 incident cases and 3,701 deaths were included. The overall incidence of notifiable infectious diseases decreased sharply during the first year of the COVID-19 pandemic (2020) compared to pre-pandemic levels (2018, 2019), and then rebounded in 2021, particularly in South China. Across the past four years, the number of deaths steadily decreased. The incidence of diseases rebounded differentially by pandemic phase. For instance, although seasonal influenza dominated respiratory diseases in 2019, it showed a substantial decline during the pandemic (% change in phase Ⅱ 2020: 0.21 95%CI[0.09-0.50]), which persisted until 2021 (% change in phase IV 2021: 1.02 95%CI[0.74-1.41]). The incidence of gastrointestinal and enterovirus diseases decreased by 33.6% during 2020, but rebounded by 56.9% in 2021, mainly driven by hand-foot-mouth disease (% change in phase Ⅲ 2021: 1.28 95%CI[1.17-1.41]) and infectious diarrhea (% change in phase Ⅲ 2020: 1.22 95%CI[1.17-1.28]). Sexually transmitted and blood-borne diseases were restrained during the first year of 2021 but rebounded quickly in 2021, mainly driven by syphilis (% change in phase Ⅲ 2020: 1.31 95%CI[1.23-1.40]) and gonorrhea (% change in phase Ⅲ 2020: 1.10 95%CI[1.05-1.16]). Zoonotic diseases were not dampened by the pandemic but continued to increase across the study period, mainly due to brucellosis (% change in phase Ⅱ 2020: 0.94 95%CI[0.75-1.16]). Vectorborne diseases showed a significant continuous decline during 2020, dominated by hemorrhagic fever (% change in phase Ⅱ 2020: 0.68 95%CI[0.53-0.87]), but rebounded in 2021.

Conclusions:

The COVID-19 pandemic was associated with a marked decline in notifiable infectious diseases in Chinese children and adolescents. These effects were not sustained, with evidence of a rebound to pre-pandemic levels by late 2021. Maintaining disease surveillance and strengthening implementation of initiatives such as extended immunization programs, stronger prioritization of sexually transmitted infections, maintaining implementable of non-pharmaceutical intervention projects, and managing imported infections will be necessary to respond to the post-pandemic rebound in overall infectious diseases in children and adolescents.