Nagasaki University School of Tropical Medicine and Global Health, Nagasaki, Japan.
Department of Paediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
Environ Health. 2021 Dec 2;20(1):122. doi: 10.1186/s12940-021-00808-w.
During 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.
We 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.
A 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%).
This 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.
在 COVID-19 大流行期间，许多疾病的发病率有所下降。在日本，与热相关的疾病发病率与大流行前相比降低了 22%。然而，导致这种下降的原因尚不清楚。在这里，我们对日本 47 个县的最高温度与热相关疾病之间的关系进行建模。我们特别研究了大流行前后暴露和滞后关联的变化。
我们从相关数据来源获得了夏季特定的、每日与热相关的疾病救护车转运（HIAT）、暴露变量（最高温度）和协变量数据。我们采用了分层（大流行前和大流行期间）、两阶段的方法。在每个分层组中，我们使用准泊松回归结合分布式滞后非线性模型来估计 1）基于县的关联，然后使用随机效应荟萃分析对其进行汇总。在暴露和滞后维度上，我们检验了汇总的大流行前和大流行期间关联之间的差异。
2016 年至 2020 年期间，日本共记录了 321655 例 HIAT 病例。我们发现，在大流行期间，HIAT 的与热相关的风险总体上有所降低，在暴露水平从 21.69°C 到 36.31°C 的范围内，HIAT 风险的降低范围很广（10.85% 到 57.47%）。相反，我们发现大流行期间滞后 2 时（16.33%；95%CI：1.00，33.98%）的与热相关的风险增加。
本研究提供了 COVID-19 影响的证据，特别是在可能改变温度与健康关系的物理干预和行为变化方面。这些发现将对后续的政策或与热相关的警告策略产生影响，以应对当前或未来的大流行。
