Effects of Hot Weather on the Spread of Covid-19

It was towards the beginning of 2020 that the news of a deadly strain of corona wreaking havoc in China and slowly spreading to the rest of the world began to seep into the Indian consciousness. The virus quickly spread to the other parts of the world and people in the West, as also in metro regions of India, were in deep dread. Otherwise known as Covid-19, a pandemic was declared by the World Health Organisation(WHO), on March 11, 2020. Several countries, including India, declared a lockdown. Movement was restricted within cities, across state and international borders. Life almost came to a standstill. Roads were deserted, shopping centres closed, transport networks came to a grinding halt; Treatment costs were exorbitant - far beyond the protection offered by health insurance. Hospitals and morgues overflowed. People suffered. The economy also came to a halt. People lost jobs and livelihoods. The elderly were perhaps the worst affected as lockdown imposed severe restrictions on socialising and movement. Schools were closed. There was hardly anyone who had not lost a close loved one.

Some countries were more affected than others. There have been several studies attempting to understand the virus, the manner of transmission, its life outside the human body and the conditions under which it thrives. As the mortality rate was noticeably far more in colder temperate countries in the initial stages, the question of whether summer slows the spread of coronavirus was also uppermost in the minds of the medical and scientific community.

What Do Research Papers Have to Say on Effects of Summer on Covid Spread?

Bukhari and Jameel in their paper entitled “Will coronavirus pandemic diminish by summer” published in the early stages of the pandemic stated that there was no conclusive evidence to support the theory that warm and humid temperatures would slow down the speed of transmission. They strongly recommended continued government intervention and personal precautions.

In a paper “Effects of Weather on Coronavirus Pandemic”, the weather patterns were analysed by the authors in different regions, on a global scale, where the virus had struck. Their results indicated that temperature had a major role to play on the effect of the virus on humans. They came to this conclusion after  comparing the death rates vis-a-vis temperatures of the region. More cases occurred in regions with temperatures below 17 degrees centigrade. This for most Indians, would be winter-like temperatures. Regions with temperatures outside the range of three to seventeen degrees accounted for only 15% of the case load till May 2020. However, their study also stated that while weather did seem to have a role to play, this role seemed to be limited in cities of Europe and North America above the 45 degree latitude. The study also pointed out that humidity appeared to have a role in the spread of the virus. They found a consistently increasing pattern in the number of cases in places where the humidity was greater than 9g per cubic meter. While interpreting the data available for the study, the researchers also stated that data from hot and humid countries may not have been holistic due to the underdeveloped or the poorly developed state of health infrastructure, as a result of which testing facilities may not have been available.

WebMD in a paper published in April, 2020, stated rather emphatically, that there was no clear evidence to support the theory that summer could slow the spread of the virus, even though there was some evidence in support of the fact that the Covid-19 virus did not survive well in heat. The virus has the capacity to rapidly mutate, thus making it difficult to say with any degree of certainty that summer does slow the spread of the virus. In Australia and Iran, they stated, even in the hot summer, at the beginning of the pandemic, the spread of the virus was extremely rapid. In fact, Australia was one the earliest countries to seal their borders in order to contain the spread of the virus.

Keiran Sharkey, a reader in the University of Liverpool, also studied data on the Covid-19 pandemic and published a paper entitled “Will Summer slow the spread of Covid-19? New Research sheds Light” in April 2021. Her research suggested that while there appeared to be some correlation between the summer and the spread of the virus, this could also be attributed to the fact that people tended to spend more time outdoors in summer, thus increasing their exposure to ultraviolet rays. She further stated that there was some evidence available that suggested that the ability of Covid-19 virus to survive on surfaces was adversely affected by ultraviolet rays.

Let’s Check Some WHO Stats

Globally, WHO reports that as of September 29, 2022, the number of confirmed cases of COVID-19 stood at 613,942,561 and included more than six million, five hundred deaths. In India, the case count was 44,583,360 with 528,611 deaths. Most of the corona pandemic related restrictions have been lifted in our country, except for mandatory masks while traveling on flight or in crowded places. While we hope that the pandemic is over, and the novel coronavirus has been reduced to the equivalent of a common flu, we need to remember the capacity of the virus to mutate. There does not appear to be any conclusive evidence to support the theory of summer slowing down the spread of the coronavirus. So, keep taking precautions and stay safe.