Abstract
BackgroundDuring the COVID-19 pandemic, several illnesses were reduced. In Japan, heat-related illnesses were reduced by 22% compared to pre-pandemic period. However, it is uncertain as to what has led to this reduction. Here, we model the association of maximum temperature and heat-related illnesses in the 47 Japanese prefectures. We specifically examined how the exposure and lag associations varied before and during the pandemic.MethodsWe obtained the summer-specific, daily heat-related illness ambulance transport (HIAT), exposure variable (maximum temperature) and covariate data from relevant data sources. We utilized a stratified (pre-pandemic and pandemic), two-stage approach. In each stratified group, we estimated the 1) prefecture-level association using a quasi-Poisson regression coupled with a distributed lag non-linear model, which was 2) pooled using a random-effects meta-analysis. The difference between pooled pre-pandemic and pandemic associations was examined across the exposure and the lag dimensions.ResultsA total of 321,655 HIAT cases was recorded in Japan from 2016 to 2020. We found an overall reduction of heat-related risks for HIAT during the pandemic, with a wide range of reduction (10.85 to 57.47%) in the HIAT risk, across exposure levels ranging from 21.69 °C to 36.31 °C. On the contrary, we found an increment in the delayed heat-related risks during the pandemic at Lag 2 (16.33%; 95% CI: 1.00, 33.98%).ConclusionThis study provides evidence of the impact of COVID-19, particularly on the possible roles of physical interventions and behavioral changes, in modifying the temperature-health association. These findings would have implications on subsequent policies or heat-related warning strategies in light of ongoing or future pandemics.
Highlights
The novel coronavirus which was first reported in Wuhan, China last December 2019 [47], has been spreading globally at unprecedented rate, leading to the virus being declared as a global pandemic by WHO [44]) on12 March 2020
We observe a discernable gradient of summer-specific maximum temperature with northern locations experiencing milder summers compared to southern locations
In either pre-pandemic or pandemic periods, the highest recorded maximum temperature was in August, whereas for relative humidity it was recorded in July
Summary
The novel coronavirus which was first reported in Wuhan, China last December 2019 [47], has been spreading globally at unprecedented rate, leading to the virus being declared as a global pandemic by WHO [44]) on12 March 2020. In Japan, the government initially rolled out three main strategies; namely: a) early cluster detection and timely response, b) enhancement of Seposo et al Environmental Health (2021) 20:122 early diagnosis and intensive care for severely affected patients, and c) universal healthcare system strengthening alongside behavioral change of the general population [35] Anchored within these major strategies are policy adaptations and requests highlighted in the “avoidance of the3C’s:Closed space,Crowded place andClose-contact setting” strategy issued on February 2020, which encourages social distancing, mask donning and indoor space ventilation [18]. The main culprit for the increase in heat-related illnesses is the exposure to extreme heat [36], amplified by the changing climate In response to this looming threat in the time of the pandemic, the Ministry of Health, Labor and Welfare (MHLW) issued guidelines, dated 4 May 2020, which was entitled and loosely translated to “Heatstroke prevention in “a new lifestyle” during the COVID-19 pandemic”, elaborating on how to prevent heatstroke while maintaining the 3Cs [32]. We examined how the exposure and lag associations varied before and during the pandemic
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