Decreased hospitalizations and deaths from community-acquired pneumonia coincided with rising public awareness of personal precautions before the governmental containment and closure policy: A nationwide observational study in Japan

BackgroundThe effectiveness of population-wide compliance to personal precautions (mask-wearing and hand hygiene) in preventing community-acquired pneumonia has been unknown. In Japan, different types of non-pharmaceutical interventions from personal precautions to containment and closure policies (CACPs, e.g. stay-at-home requests) were sequentially introduced from late January to April 2020, allowing for separate analysis of the effects of personal precautions from other more stringent interventions. We quantified the reduction in community-acquired pneumonia cases and deaths and assessed if it coincided with the timing of increased public awareness of personal precautions before CACPs were implemented. MethodsA quasi-experimental interrupted time series design was applied to non-COVID-19 pneumonia hospitalization and 30-day death data from April 2015 to August 2020 across Japan to identify any trend changes between February and April 2020. We also performed a comparative analysis of pyelonephritis and biliary tract infections to account for possible changes in the baseline medical attendance. These trend changes were then compared to multiple indicators of public awareness and behaviors related to personal precautions, including keyword usage in mass media coverage and sales of masks and hand hygiene products. FindingsHospitalizations and 30-day deaths from non-COVID-19 pneumonia dropped by 24.3% (95% CI 14.8 to 32.8, p < 0.001) and 16.1% (95% CI 5.5 to 25.5, p < 0.005) respectively in February 2020, before the implementation of CACPs, whereas pyelonephritis and biliary tract infections did not suggest a detectable change. These changes coincided with increases in indicators related to personal precautions rather than those related to contact behavior changes. InterpretationCommunity-acquired pneumonia could be reduced by population-wide compliance to moderate precautionary measures, such as wearing masks and hand hygiene. FundingJSPS KAKENHI Grant Number 22K17329 and JSPS Overseas Research Fellowships. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSThe impact of personal precautions on community-acquired respiratory disease has been studied mainly for influenza and coronavirus infections, but no studies have evaluated the number of hospitalizations or 30-day deaths from overall non-COVID-19 pneumonia. We searched PubMed and medRxiv until May 3, 2022, for studies on the impact of personal precautions on community-acquired pneumonia using the following terms in the title and abstract: ((personal precaution*) OR (mask*) OR (non-pharmac*) OR (nonpharmac*)) AND (pneumonia). Before November 2019, when COVID-19 first emerged, no study was found that evaluated the impact of personal precautions such as masks on all-cause community-acquired pneumonia. After the emergence of COVID-19, there have been several reports of the relationship between non-pharmaceutical interventions (NPIs) and a decrease in non-COVID-19 pneumonia, but all reports evaluated the impact of general NPIs that aggregated different types of interventions, including personal precautions, physical distancing, and movement restrictions, and no studies were found that evaluated the impact on overall non-COVID-19 pneumonia from personal precautions alone. Added value of this studyOur study found a reduction in hospitalizations and deaths from non-COVID-19 community-acquired pneumonia in Japan, especially those among the elderly population, had been detectable before the implementation of physical distancing policy and movement restrictions including stay-at-home requests. This reduction coincided with an increase in multiple indicators of public awareness of personal precautions, suggesting the potential benefit of population-level compliance to personal precautions (mask wearing and hand hygiene) against community-acquired pneumonia. Implications of all available evidenceMaintaining a certain level of personal precautions in the population, e.g. by mask recommendations, may provide a positive public health impact even in the post-COVID era via reduced incidence of a spectrum of infectious diseases: most importantly, pneumonia as a major cause of death in the elderly. Since personal precautions are more sustainable than stringent restrictions such as lockdowns and could largely coexist with normal economic activities, long-term recommendations for personal precautions, at least in certain parts of the society, may warrant further discussion.