Unraveling varying spatiotemporal patterns of dengue and associated exposure-response relationships with environmental variables in Southeast Asian countries before and during COVID-19.

Dengue fever is a typical tropical disease transmitted via mosquito bites. COVID-19 lockdowns have altered human-mosquito contact patterns that impacted dengue transmission. Additionally, lockdowns caused short-term environmental changes that affected dengue vector breeding. In fact, during the COVID-19 period, the normal prevention and treatment of dengue in many dengue-endemic countries was negatively affected due to the sweep of COVID-19, such as strained allocation of medical resources and misreporting of cases. Therefore, this offers a unique chance to study the impact of COVID-19 on dengue transmission, guiding targeted and reasonable prevention measures. We used a series of analytical approaches including time series analysis, space-time scan statistics, and distributed lag non-linear model to compare the differences in dengue transmission patterns and its exposure-response relationships with four environmental variables (average monthly precipitation, average monthly relative humidity, monthly maximum temperature, and monthly minimum temperature) before and during COVID-19 in three Southeast Asian countries: Malaysia, Singapore and Thailand at the province scale. We found that the dengue transmission pattern and its relationship with the environmental variables changed differently. For instance, seasonality and infections heightened in Singapore during COVID-19 and peak relative risk between max temperature and dengue has rose significantly in Northern Thailand.