Heat and humidity expected to reduce transmission of coronavirus, says new study
Scientists expect slowed growth of the virus in the coming few months
Dubai: Finally, there might be some good news on the coronavirus. And it’s coming out of China.
A scientific paper supported by a grant from the National Natural Science Foundation of China predicts Covid-19’s transmissibility to reduce a lot by the end of March in some countries. The reason – hot and humid weather.
While the discomfort of summer is usually not welcome, this time around it might prove to be one of the best weapons to combat the wildfire spread of the novel coronavirus.
The paper by Jingyuan Wang, Ke Tang, Kai Feng and Weifeng Lv, published on March 10 and revised on March 19, “investigates how air temperature and humidity influence the transmission of COVID-19”.
It is traditionally known that transmission of viruses are affected by “climate conditions (such as temperature and humidity), population density and medical care quality”. So, it has become imperative for the scientific community to understand the impact of temperature and relative humidity on the novel coronavirus, to be able to forecast in some measure the “intensity” and the end of the pandemic.
In fact, on March 06, 2020, Michael Ryan, the executive director of the WHO Health Emergencies Program, said that the transmissibility of the COVID-19 virus in different climatic conditions is still unknown.
The Chinese study on coronavirus
The results of this new study are based on the research of 100 Chinese cities with more than 40 cases in each, by the scientists.
The report states: “… high temperature and high relative humidity significantly reduce the transmission of COVID-19, respectively, even after controlling for population density and GDP per capita of cities.”
They found that “outbreaks of COVID-19 outside China show a noteworthy phenomenon. In the early dates of the outbreak, countries with relatively lower air temperature and lower humidity (e.g. Korea, Japan and Iran) see severe outbreaks than warmer and more humid countries (e.g. Singapore, Malaysia and Thailand) do.”
As part of the study, they also factored in elements such as social distancing and high quality healthcare availability. Because, if people stay at home, then it is not logically possible to study the transmissibility of the virus.
The behaviour
Some of the facts the paper said the scientists worked with were that the influenza virus, which is also a coronavirus, “is more stable in cold temperature, and respiratory droplets, as containers of viruses, remain airborne longer in dry air. … cold and dry weather can also weaken the hosts’ immunity and make them more susceptible to the virus. These mechanisms are also likely to apply to the COVID-19 transmission. Our result is also consistent with the evidence that high temperature and high relative humidity reduce the viability of SARS (Severe Acute Respiratory Syndrome) coronavirus.”
In fact, the study points out that an increase in temperature by a degree and in relative humidity by one per cent has a significant impact on the movement of the coronavirus.
“This result is consistent with the fact that the high temperature and high humidity significantly reduce the transmission of influenza. It indicates that the arrival of summer and rainy season in the northern hemisphere can effectively reduce the transmission of the COVID-19.”
So, how did they arrive at this conclusion?
They studied the transmission of the coronavirus in various Chinese cities, factored in expected weather changes including temperature and relative humidity by assuming that it would be similar to the patterns of March and July of 2019, and found a distinct pattern that varies for temperate and tropical countries.
In July, the arrival of summer and rainy season in the northern hemisphere can effectively reduce the transmission of the COVID-19; however, risks remain in some countries in the southern hemisphere (e.g. Australia and South Africa).
The paper stated: “In July, the arrival of summer and rainy season in the northern hemisphere can effectively reduce the transmission of the COVID-19; however, risks remain in some countries in the southern hemisphere (e.g. Australia and South Africa). If we plug the normal summer temperature and relative humidity of Tokyo (28C and 85%, respectively) … the transmission of the COVID-19 in Tokyo will be seriously reduced between March and the Olympics….”
Coronavirus recovery model
The study results tie in with conclusions being drawn by a Nobel Laureate in chemistry and biophysicist from the US, Michael Levitt. He was recognized for developing complex models of chemical systems.
As per a Los Angeles Times report, he had accurately predicted the curve of the coronavirus outbreak in China a while ago. Levitt had predicted that China would “end up around 80,000 [COVID-19 cases], with about 3,250 deaths”. As of March 16, China had 80,298 cases and 3245 deaths, with the virus on the wane in the country.
Levitt has “analysed 78 countries with more than 50 reported cases of COVID-19 every day and sees ‘signs of recovery’”. He sees clear signs of “slowed growth” and expects the world to come out of this crisis, but feels it is necessary “to control the panic”, practice social distancing and self-hygiene.