Coronavirus myth busted: COVID-19 cases may not decline in warm climate

Even if you are not constantly following coronavirus updates you might have heard about the common suggestion that the virus may just die off once the temperature rises. And how this would be good news for the northern hemisphere where summers are just around the corner.   [caption id=“attachment_7996191” align=“alignleft” width=“380”]  Representational image. Image source: Getty Images.[/caption] This belief is coming mostly from the fact that influenza or flu mostly shows up in winters. Also, SARS outbreak (that was caused due to a related coronavirus) had died out in summer months. SARS or Severe Acute Respiratory Syndrome is a respiratory illness caused by the SARS-CoV virus. It has almost similar symptoms to that of COVID-19 (caused by the SARS-CoV-2 virus) and had lead to a massive outbreak in the year 2002-03. However, Michael Ryan, Executive Director, WHO Health Emergencies Programme, said last Friday that it would be a false hope to believe that COVID-19 would disappear in summers like the flu.   Here is what we know so far on the temperature sensitivity of COVID-19 and why it is too early to make any claims.

The uncertainties

There is a lot that we don’t know about the novel coronavirus SARS-CoV-2 as it is still new and scientists are still trying to understand its behaviour.   In his article published on the online portal of the Center for Communicable Disease Dynamics, Marc Lipsitch, a professor of Epidemiology and Director, Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public Health, explained why the COVID-19 may not disappear in the summer months and why we can’t compare it to SARS and flu.   He said that what had contained SARS was not the warmer temperature but extensive public health measures. The disease had come back to Toronto the moment they had stopped taking some of their precautionary measures. We have no idea of the environmental factors that influence the spread of the novel coronavirus. Right now, the novel coronavirus seems to be spreading in a variety of environmental conditions. This is unlike the flu virus, which we know spreads more in cold and humid conditions. Some coronavirus strains, particularly those that cause the common cold, do spread more in winter months and if this new virus is like them, it may just keep coming back every winter. But right now speculations are all that we have.   Another thought is that in winter months people tend to stay indoors in closed spaces that can readily spread the virus. Also, school terms have a huge impact on spread on respiratory diseases but then again COVID-19 doesn’t seem to be affecting children that much, according to current statistics. It is also possible that children are getting a mild form of the disease. This is also unlike the flu since young children at considered highly at risk of contracting the flu.   In the Friday press release, Dr Ryan said something similar, pointing out the human behaviour in winters and how it may lead to an easier spread of the virus in colder months. And finally, there is a factor that SARS-CoV-2 is totally new to the human immune system. Those who have not yet developed immunity to the virus would get the disease no matter the season. “Even seasonal infections can happen “out of season” when they are new,” explained Lipsitch.  

May love colder temperatures

In a study done in China, researchers have found that COVID-19 spreads more readily at a temperature of 8.72 degrees Celcius and with every 1-degree rise in the minimum temperature, the total number of cases may go down a bit. Note the word ‘readily’ and the total number of cases. It means that 8.72 is maybe the best temperature for the virus to transmit and it is likely that more cases would show up in colder climates. Nowhere is it said that higher temperature would inactivate or kill the virus. The study is yet to be peer-reviewed and was based on the daily cases reported in China only.   So far, there is no concrete evidence to say that the virus would die off in summers. For more tips, read our article on   Coronavirus_._ Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.