Will high temperatures help us contain COVID-19 coronavirus? We can’t count on it too much: that’s what science says.
Will spring and summer end the COVID-19 coronavirus ? Some experts speculate that it is possible, and some politicians – such as the President of the United States Donald Trump – are loudly proclaiming it. But the truth is, we simply don’t know ; viruses do not behave so predictably, and resting on false hopes could play our disadvantage.
In fact, some respiratory viruses have a seasonal pattern, and with the heat they spread less efficiently. It could depend on the interactions between pathogens and weather conditions: some studies show, for example, that flu epidemics in temperate climate areas emerge when absolute humidity levels drop(the density of water vapor in the air), i.e. with the arrival of winter air, dry and cold. But the prevalence of certain ailments in winter could also depend on a lower efficiency, this season, of our immune system, dry of vitamin D; or from the fact that, in the cold, we tend to frequent closed and crowded places for a long time, while in the summer we spend as much time as possible outdoors. In addition, schools are closed in the summer, and the risk of contagion among children is less.
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It is too early to understand whether the COVID-19 coronavirus is a seasonal virus. We have not had experience in the past, and SARS and MERS are not necessarily valid terms of comparison. As far as we know, the pathogen seems to be doing well in tropical areas, as its spread in Singapore shows. For many virologists it is unlikely that the heat will knock it down: the high temperatures could make the infection more difficult, but bring it back into vogue next winter, after a period of relative quiet, transforming it into an endemic threat. If the COVID-19 coronavirus preferred lower temperatures, the summer would entail an increased risk for the countries of the South of the world, which are heading towards the cold season. And there is the unknown air conditioning, which could distort the perceived temperatures indoors or facilitate the spread of the pathogen.
The arrival of summer may have helped in part to halt the SARS epidemic, which however was stopped mainly thanks to the intense containment efforts put in place globally. Basking on false hopes risks letting us drop our guard, diverting us from the only effective measures: those of prompt medical isolation of suspected cases and quarantine of the infected. Furthermore, the MERS coronavirus began in the summer in the scorching regions of the Gulf countries; and there are cases in which the flu does not respect the calendar, as happened for the pandemic of H1N1, which flourished in the spring-summer of 2009. In short, in order not to venture premature hypotheses it will be necessary to wait for April and see what happens. But without hoping too much.