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Scientists explain if whether or not heat and humidity can help reduce the spread of the infectious and deadly COVID-19 pandemic in a recently published health article.


The seasonality of the flu and other related respiratory diseases has been known for centuries. Akiko Iwasaki, a professor of immunobiology at the Yale University School of Medicine, said that there is a surge of respiratory infection and influenza viruses during winter months.  

Iwasaki said that the dry air during winter makes it possible for the viruses to become airborne. He even described this season as the "perfect setting" for the transmission of respiratory illnesses.  

She said: "When you cough or sneeze or even talk, you're generating these droplets that are coming out of your mouth. And some of them, if you're infected, will contain virus particles. In very arid conditions, those particles lose water vapor, and they become airborne." This means that the virus remains in the air for a more extended period in winter than in summer.


Iwasaki answers this question: "This novel coronavirus is a cousin of the coronaviruses that are circulating in humans and causing the cold. So the property of the virus is likely to be similar to the common cold version of the coronavirus. So I would expect that this [new] coronavirus can also stay in the air better at lower relative humidity, meaning the indoor conditions that you find in the winter months."

This means that Iwasaki believed that COVID-19 is more likely to spread during the winter season, but for this to happen, there should be an airborne transmission. 

However, the World Health Organization and the U.S. Centers for Disease Control and Prevention downplay the possible airborne spread of COVID-19 based on their guidance. They believed that the primary transmission of the new virus is through large respiratory droplets.

They said: "This debate - airborne vs. droplets - is a crucial divergence in thought when it comes to figuring out if COVID-19 is going to be seasonal. If the primary form of transmission is airborne, then the novel coronavirus could become a seasonal disease. If it mainly spreads through "large respiratory droplets."

If large respiratory droplets can spread the new virus, then this means that seasonality will not matter. Also, this means that COVID-19 is the same as with Severe Acute Respiratory Syndrome (SARS) that emerged in 2003, as it too can be spread through large droplets.

Meanwhile, the World Health Organization agrees that COVID-19 can be aerosolized, but the global health body firmly believed that this is not the primary transmission of the new virus.

However, some researchers gave cautioned of assuming that any virus, regardless of how it spreads, follows a seasonal pattern. 

Anice Lowen, an associate professor of microbiology and immunology at Emory University, said that everyone is susceptible to the virus, and it will continue to spread through the summer.

Another epidemiologist from the University of Hong Kong Ben Cowling supported the statement of Lowen. He said that higher temperature has not seemed to stop the spread of the virus. 

Cowling said: "What we've seen in Southeast Asia is that there was heavy seeding of infections [from China] into Thailand, into Malaysia, Indonesia, and some other places which are relatively hotter." He also added that the transmission of this new virus in these countries might drop by 10 percent, but it is not fair to say that summer will stop the pandemic.