Effect of cold spells and heatwaves on daily new cases of COVID-19 in the Western Pacific Region: A time series analysis.

OBJECTIVES

The relationship between extreme temperature events and COVID-19 transmission remains a subject of ongoing debate, particularly in the Western Pacific Region (WPR).

STUDY

DESIGN

An ecological study.

METHODS

A comprehensive analysis of daily confirmed COVID-19 cases and meteorological data from 18 WPR countries, covering the period from January 1, 2020, to December 31, 2022, was conducted. We developed a Distributed Lag Nonlinear Model (DLNM) that incorporated variables such as climate zones, population density, human development index, and government response stringency.

RESULTS

Our analysis of over 180.3 million confirmed cases revealed significant correlations between patterns of extreme temperature fluctuations and COVID-19 transmission in the WPR. Specifically, heatwaves (HWs) that exceeded the 95th percentile of daily mean temperature for more than four days were associated with a significant increase in COVID-19 transmission risk, with the highest susceptibility observed in the tropical zone (cumulative relative risk of 2.226). Similarly, cold spells (CSs) that fell below the 5th percentile for over three days also heightened the risk of COVID-19 transmission, particularly in temperate regions, with a cumulative RR of 4.148. Further analysis indicated that prolonged durations of HWs and CSs significantly amplify their respective impacts.

CONCLUSIONS

This study underscores the necessity of considering environmental factors in pandemic management and offers valuable insights for the development of targeted public health interventions and early warning systems tailored to specific climatic conditions.