It’s one of the most important questions: how will the novel coronavirus react to rising temperatures? Initial hopes that the virus might simply be killed by high temperatures took a serious blow, as the coronavirus seemed to also spread in warm weather.

However, according to a newly published study, higher temperatures at least slow down the virus.

SARS-CoV-2, the virus causing the current pandemic, is not the most lethal virus we’ve seen. It’s not the most contagious one we’ve seen, either. However, it seems to have hit a “sweet spot” between how fast it can spread and how lethal it is.

It also seems to be surprisingly resilient to high temperatures. We were hoping that it will simply go away during the warm season (like the influenza) — but this seems very doubtful at the moment. The virus has managed to spread in Singapore and several other countries at temperatures of over 30 degrees Celsius (86 Fahrenheit), and it seems rather unlikely that warm weather will simply kill the virus.

But it might slow it down.

A team of data scientists and economists at Beijing schools Tsinghua University and Beihang University, using data from the Chinese Center for Disease Control and Prevention, analyzed how contagious the virus is depending on temperature.

Their analysis looked at 4,711 confirmed cases of the SARS-CoV-2 coronavirus in Chinese cities. They used refined statistical tools to model how the weather affects disease transmission, and eliminate other factors that might be at play.

It’s still preliminary data, it’s by no means conclusive, but here’s what the data says so far.

The more the temperature and humidity increase, the lower the R₀ of the virus. This R₀ parameter (called the basic reproductive ratio) is key in any outbreak. It essentially means “if a person is infected, to how many people will they pass it on” — for instance, if R₀ = 2, then infected people will, on average, pass it to 2 other people. A lower R₀ means the disease is likely to pass to fewer people. An R₀ below 1 means the disease will eventually disappear.

“One degree Celsius increase in temperature and one percent increase in
relative humidity lower R by 0.0266 and 0.0106, respectively. 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,” the Chinese researchers wrote.

This seems like little consolation — it’s a seemingly small drop; but it can make a world of a difference, especially since infection can be exponential.

In the context of “flattening the curve”, it could buy us valuable time, slowing the spread of the disease and ensuring that health care systems aren’t overburdened by a surge of COVID-19 cases.

What does this mean for the next season? It’s good news for the Northern Hemisphere and bad news for the Southern.

It means that for most of Asia, Europe, and North America, the situation might improve after a few months. But we still have a long way to go until then.

The paper can be accessed freely on the pre-print server arXiv.