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COVID-19 and the effect of extreme weather events

This post was written by Professor Piero Olliaro, Director of Science at ISARIC, University of Oxford; Dr. Lakshmi Manoharan, MBBS MSc Public Health, University of Oxford; and Josephine Bourner, Clinical Trial Manager, University of Oxford

 ‘Scientists ask: could summer heat help beat Covid-19?’

              -The Guardian, 5 April 2020[1]

At the beginning of the pandemic, the possibility that warmer weather could reduce the transmission of COVID-19 in the northern hemisphere was repeatedly raised by the public, media and the scientific community. [1-3] As weeks and months continue to pass, the global spread of COVID-19 has demonstrated it can have a catastrophic effect on populations living in a variety of temperatures. However, the true impact of COVID-19 seasonality remains uncertain.

The focus on weather and its ability to stem the transmission of COVID-19 simplifies what weather can be: hot or cold, wet or dry, summer or winter. Instead, the conversation should consider the complications. Disruptions in these weather patterns could be equally as disruptive to efforts to control the transmission of COVID-19: specifically, extreme weather events associated with warm, humid conditions, such as cyclones and hurricanes. The aftermath of these events often disproportionately affects low- and middle-income countries.4]

In addition to the devastation that cyclones and hurricanes can cause in communities, the risk of disease outbreaks is high. Malaria, cholera, diarrhoeal and respiratory diseases are commonly reported due to flooding, damaged sanitation infrastructure and, most significantly, population displacement – the mass movement of people from a disaster-hit area to an area of safety.[5] This will often lead to the large-scale congregation of people in organised relief shelters, informal shelters or in the homes of friends and family. Physical distancing, a key COVID-19 prevention measure, is often impossible in these situations.

Relief shelters are often densely populated spaces, requiring people share amenities and narrow passages with a large number of people. In these settings, the incidence of acute respiratory infections (ARI) increases. Following extreme weather events, ARI outbreaks often see their peak pushed months earlier and are reported in much higher numbers.[6] An increase in respiratory infections occurred at the community-level in Myanmar following Cyclone Nargis in 2008, and again in a shelter in Texas in 2017 following Hurricane Harvey.[6,7]  Cramped conditions increases risk of transmission of respiratory infections and these conditions are difficult to control in shelters with limited space.[8]

Population displacement and overcrowded housing may in turn make other COVID-19 prevention strategies difficult to implement. Aside from maintaining at least a 1-meter distance from others and avoiding crowded places, the WHO advises regular handwashing. In developing countries, poor access to clean water may be worsened by damage to critical sanitation infrastructure rendering regular hand washing difficult. Another tenet of COVID-19 prevention is to self-isolate if symptoms appear, which may not be an option if people need to seek healthcare, find food or queue for relief packages.

Despite this, informing people in disaster zones about the dangers of the virus and necessary precautions is essential. Emergency relief workers will be critical in stemming potential increases in transmission of COVID-19 in relief shelters and the general community. The greatest tool we could give to these key agents is COVID-19 specific training. Familiarity with COVID-19 presentations, effective PPE use and local medical referral pathways is essential. Additionally, cyclones and hurricanes are notorious for disrupting supply chains. Amid a pandemic where governments have placed restrictions on business and travel, working with local authorities will be critical to ensure that these measures do not inhibit the supply of essential items.

In the past following disastrous extreme weather events, governments and relief agencies have supported efforts to keep communities safe. The response now and in the future will need to be different. The emergency response will have to focus on the integration of COVID-19 prevention strategies in to existing structures. Local and national agencies will need to work together in emergency situations to prevent COVID-19 overwhelming vital support systems and reduce the burden of deaths from both extreme weather events and the virus.  


[1] McKie R. Scientists ask: could summer heat help beat Covid-19? The Guardian. Available from: [Accessed May 2020]

[2] Lipsitch M. Seasonality of SARS-CoV-2: Will COVID-19 go away on its own in warmer weather? Harvard T.H. Chan School of Public Health. Available from: [Accessed May 2020]

[3] Sajadi MM, Habibzadeh P, Vintzileos A, et al. Temperature, humidity, and latitude analysis to predict potential spread and seasonality for COVID-19. SSRN. 2020. Available from: [Accessed May 2020]

[4] Doocy S, Dick A, Daniels A, Kirsch TD. The human impact of tropical cyclones: a historical review of events 1980-2009 and systematic literature review. PLoS Curr. 2013;5. Available from: doi:10.1371/currents.dis.2664354a5571512063ed29d25ffbce74

[5] Watson JT, Gayer M, Connolly MA. Epidemics after natural disasters. Emerg Infect Dis. 2007;13(1):1‐5. doi:10.3201/eid1301.060779

 [7] Liu L, Haynie A, Jin S, et al. Influenza A (H3) Outbreak at a Hurricane Harvey Megashelter in Harris County, Texas: Successes and Challenges in Disease Identification and Control Measure Implementation. Disaster Med Public Health Prep. 2019;13(1):97‐101. doi:10.1017/dmp.2018.159

[8] Al-Khatib IA, Ju’ba A, Kamal N, et al. Impact of housing conditions on the health of the people at al-Ama’ri refugee camp in the West Bank of Palestine. International Journal of Environmental Health Research. 2003;13(4):315-326. doi:10.1080/09603120310001616092

[9] WHO. Coronavirus disease (COVID-19) advice for the public. Available from: [Accessed May 2020]

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