Impact of the COVID-19 pandemic and COVID-19 downgrade on non-COVID-19 respiratory diseases in Japan

Objectives

A worldwide decrease in the incidence of respiratory diseases during the coronavirus disease (COVID-19) pandemic has been reported, largely due to non-pharmaceutical interventions (NPIs). However, the impact of lifting NPIs remains unclear. In Japan, NPIs were lifted rather drastically when COVID-19 was downgraded on May 8, 2023. This study aimed to evaluate the impact of the COVID-19 pandemic and its downgrade on non-COVID-19 respiratory diseases using nationwide databases.

Study design

Retrospective cohort study.

Methods

Monthly hospitalisation and prescription rates between January 2017 and October 2023 were collected from the JMDC insurance claims database covering 16,485,812 insured individuals. The monthly mortality rates in Japan were collected from an open data source published by Ministry of Health, Labour and Welfare of Japan. Interrupted time series analyses using seasonal autoregressive integrated moving average models were performed.

Results

While hospitalisation rates for diseases such as pneumonia, asthma, and aspiration pneumonia decreased during the pandemic, a step increase in hospitalisations for these diseases and prescriptions for anti-asthma drugs was observed following the COVID-19 downgrade. The pandemic impacted all age groups; however, the impact of COVID-19 downgrade was more pronounced in children aged 0–5 years. Although mortality from non-COVID-19 respiratory diseases decreased during the pandemic, no immediate step increase in mortality was observed following the downgrade.

Conclusions

Although hospitalisations for pneumonia and prescriptions for anti-asthma drugs increased immediately after downgrading COVID-19, no step increase in mortality was observed presumably because older people were less affected than children.