Rise in temperatures unlikely to kill off coronavirus

No indication warm weather will have same effect on Covid-19 like it does on flu, says expert

Artist Gerard Byrne who normally paints outdoors and is known for his landscape and architectural paintings has set up his easel on the roof of his Ranelagh Fine Art Studio Gallery in Dublin. Photograph: Bryan O’Brien

As people prepare to bask in unseasonably warm weather over the Easter bank holiday weekend – with temperatures of up to 19 degrees in Ireland – there is nothing to indicate it will be killing off coronavirus to any great extent.

There is, however, strong evidence the flu virus goes into decline in warmer summer months, and it is mainly spread in the exact same way as coronavirus, also known as Covid-19, by way of small mucus droplets suspended in the air, according to immunologist Prof Kingston Mills of Trinity College Dublin.

When a person coughs or sneezes it generates aerosol droplets which are by far the most common route of infection, he explained. Where there are conditions of warmer temperatures and high humidity, those droplets are more likely to fall to the ground and not cause infection.

Exposure

This is one of the reasons why flu is seasonal and dominant in winter. The other is because exposure to the cold during winter coincides with immune systems being stressed, so going out in the cold and wet often leads to sniffles and a cold some days later.

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“There is no indication that any of this applies to Covid-19,” Prof Mills said. It may prove to be the case but caution had to be applied.

While Ireland is expecting temperatures of up to 19 degrees on Friday, "Spain will be a damn sight warmer, and look at what it's going through," he said – in reference to its Covid-19 cases.

Australia in its recent summer and parts of Africa had many cases, he added, while seasonal viruses like influenza and the viruses that cause the common cold do not completely disappear during summer.

There is a lot of ongoing research attempting to determine if Covid-19 will behave like flu.

Transmission

Communities living in warmer places appear to have a comparative advantage to slow the transmission of coronavirus infections, according to early analysis by scientists at the Massachusetts Institute of Technology.

They found most coronavirus transmissions had occurred in regions with low temperatures, between 3 and 17 degrees.

However, MIT computational scientist Dr Qasim Bukhari said the possible correlation between coronavirus cases and climate should not lead policymakers and the public to be complacent.

“We still need to take strong precautions. Warmer temperatures may make this virus less effective, but less effective transmission does not mean that there is no transmission.”

Met Éireann said highest temperatures on Saturday would be between 12 and 17 degrees. Easter Sunday is due to be bright but slightly cooler.

– Additional reporting: New York Times

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times