Two years of the pandemic suppressed deaths from non-COVID-19 respiratory infections: A nationwide surveillance in Japan.

Abstract

We, with a great interest, read the article by Dr. Ko et al. regarding how the coronavirus disease 2019 (COVID-19) pandemic affected respiratory admission.1 They revealed a decrease in influenza rate and pneumonia hospitalizations using the data in Hong Kong. We thought to quickly report 2-year result of respiratory deaths in Japan. The Japanese Ministry of Health, Labour and Welfare provided us death statistics derived from death certificates covering all residents in Japan. This dataset contains data from January 2009 to March 2022. The top 10 respiratory causes in the pre-pandemic era were selected. The number of deaths was recorded on a monthly basis. The observational period was divided into ‘pre-pandemic era’ and ‘pandemic era’. The ‘pandemic era’ was defined as April 2020 and thereafter because the national government declared the first state of emergency in April 2020. Interrupted time series analysis with a level change regression model assessed whether the pandemic affected the number of deaths after incorporating chronological trends irrelevant to the pandemic.2 Two explanatory variables were number of months since the January 2009 and ‘pandemic era’ compared to ‘pre-pandemic era’. The statistical significance threshold was set at p < 0.05 (Figure 1). Compared to the pre-pandemic period, monthly deaths from respiratory infections decreased as follows: pneumonia (−1848, 95% CI: −2587 to −1109, p < 0.001), seasonal influenza (−285, 95% CI: −43 to −14, p < 0.001), pulmonary tuberculosis (−16, 95% CI: −25 to −8, p < 0.001), acute bronchitis (−9, 95% CI: −14 to −4, p < 0.001) and invasive pneumococcal infections (−6, 95% CI: −8 to −4, p < 0.001). The pandemic also reduced deaths from chronic obstructive pulmonary disease (COPD) (−153, 95% CI: −229 to −76, p < 0.001) and bronchial asthma (−22, 95% CI: −38 to −7, p = 0.006). However, deaths from respiratory malignancies, aspiration pneumonia and interstitial pneumonia remained unchanged. We assume that infection control manoeuvres and policies to hamper severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread also prevent other respiratory infection-related deaths in these countries.1 Respiratory infection also cause COPD exacerbations and asthma attacks. However, deaths from cancers, aspiration pneumonia and interstitial pneumonia could not be suppressed by masking and physical distance. Recent mutations in SARS-CoV-2 have attenuated its lethality; thus, infection control policies are becoming less stringent. Appropriate infection protection manoeuvres should continue to suppress respiratory diseases, even after the pandemic.1, 3 None declared.