Dengue outbreaks in the COVID-19 era: Alarm raised for Asia

Abstract

Havoc associated with the novel Coronavirus Disease 2019 (COVID-19) pandemic is placing unprecedented pressure on healthcare and public health system worldwide.With medical resources and personnel being directed to battle COVID-19 globally, the pandemic may have grave repercussions in the resurgence of other infectious diseases such as dengue fever, especially in resource-limited countries with both endemic dengue and intense COVID-19 transmission.During the COVID-19 pandemic, dengue cases spiked in Brazil, introducing an added burden on already fragile healthcare systems [1].The COVID-19 pandemic coincided with a resurgence of dengue in Brazil, raising concern for countries in Asia where dengue occurring across tropical and subtropical regions of Asia accounts for approximately 70% of the global disease burden [2].Considering the region's extremely high burden of dengue, its climate change vulnerability and-imminently-the beginning of the monsoon season, there needs to be concerted actions to prevent large dengue outbreaks during and beyond the COVID-19 pandemic.Preventing or reducing dengue virus transmission depends primarily on mosquito vector controls including interrupting human-vector contact.At a time of continuous lockdowns, when public health staff are diverted to control COVID-19 transmission and community engagement focused on the pandemic, routine mosquito vector surveillance and control programs are discontinued or paused in many countries [3], which will impair dengue control and prevention.A study of India found that the immature density of Aedes mosquito drastically increased during the COVID-19 lockdown due to paused vector control programs [4], and an increased density of vectors was also reported in Malaysia during the COVID-19 lockdown, which has led to increased dengue incidence [5].During the lockdowns, when human movement is limited to and around own homes, perversely, human-vector contact may be enhanced, resulting in an increased risk of exposure and virus transmission.This impact is likely to be even more pronounced in settings where dengue virus transmissions primarily occur in or between households, rather than an occupational setting.A study quantified the impact of lockdowns on dengue incidence and suggested that a rise in dengue cases associated with lockdowns in Thailand; however, no significant impact on dengue transmission was found in Singapore and Malaysia [6].A robust study in Thailand found that 60% of dengue cases living less than 200m apart came from the same transmission chain, providing strong evidence that residences play a primary role in dengue virus transmission [7].Conversely, in areas where mosquito density