Change of seasons may slow down coronavirus – study

THE novel coronavirus pandemic that’s killed thousands, sickened more than 350 000 and sent major economies into a tailspin may be slowed by the upcoming changing of the seasons, several preliminary studies suggest.

However, research on how the coronavirus behaves in various temperature and humidity levels is only just getting under way.

Multiple early studies provide evidence of statistical ties between temperature and humidity ranges and the geographic regions where this virus has thrived. While none of these studies has been peer-reviewed, they all point to the same general possibility: the pandemic could ease in parts of North America and Europe during the summer months, though it could then come roaring back in autumn.

The anecdotal evidence suggesting a possible connection between the rate of spread of Covid-19, the illness the novel coronavirus causes, and temperature emerged early on. One of the most puzzling things about the pandemic in Asia is why many countries and territories in the region have apparently been spared major, rapidly growing outbreaks, despite close contacts with China, where the outbreak began.

The success of places like Taiwan, Singapore and Hong Kong in tamping down the epidemic could be ascribed to quick and decisive action by their governments plus effective social distancing by local residents.

But that doesn’t fully explain why Cambodia, Thailand, Vietnam and the Philippines have largely been spared mass outbreaks, at least not on the scale seen in Western Europe and the US. All had huge numbers of Chinese visitors at the start of the year, have crowded cities and relatively simple health-care systems.

Cambodia was criticised early in the epidemic for failing to close its borders with China and even failing to promote the wearing of masks.

Nearly two months since its first case, the country has recorded only 86 cases of coronavirus, with almost all infections contracted abroad. Compare that to the US, which added 10 000 cases during the past three days.

In recent weeks, there has been a rise in cases in many hotter countries as testing has expanded, although many of the cases have been imported from Europe or the US. In the southern hemisphere, Australia has seen a sharp rise in cases, but most are thought to have been acquired abroad.

There are countless examples where the virus has been transmitted between people within warmer and more humid places, and several examples of infection clusters within hotter countries. One of the biggest clusters was a four-day religious gathering at a mosque in Malaysia from February 27 to March 1, with more than 800 people testing positive for the virus, and carrying the infection to at least a half-dozen other nations.

Hundreds of people in Thailand are thought to have contracted the virus at boxing events held in Bangkok, and others in bars. However, none of these tropical countries has seen the virus grow exponentially as it has in Italy, Spain, France and the US.

A new study on research site SSRN finds that 90% of the coronavirus transmissions so far have occurred within a specific temperature and humidity range. The best-case scenario, according to the study’s authors, is that the rate of spread in parts of the northern hemisphere will slow as temperatures warm and humidity increases.

However, the researchers caution that even in warm, humid regions, governments need to implement measures to slow the spread of the virus, since warm weather could inhibit but not eliminate the spread of the virus. Study co-author Yusuf Jameel says even tropical countries are seeing this virus spread, albeit at slower growth rates. In the southern hemisphere, where winter will soon set in, countries could see their temperature and humidity levels fall within the range associated with the most rapid growth rates.

David Heymann, a professor at the London School of Hygiene and Tropical Medicine, said: “If the virus has any characteristics that impede its transmission in hot and humid climates, it has not yet manifested them in the tropics.” | Washington Post