Rates of Long Covid fall if the virus is caught in warmer months, research suggests.
An article in the Mirror said that catching Covid-19 at a warmer time of year makes people less likely to develop long Covid. This is a misunderstanding of research by Imperial College, London.
The article said: “Researchers believe catching the virus in the colder winter months may be a factor in whether some symptoms persist.”
But Matthew Whitaker, one of the scientists behind the research, told Full Fact: “The article in the Mirror is wrong on an important point: the time of infection was not the relevant variable.”
In fact, research conducted in May 2021 showed a lower prevalence of long Covid than research conducted in autumn and winter 2020/21. But these fieldwork dates don’t refer to when people actually caught Covid in the first place.
This latest research has not yet been published, but Mr Whitaker told us by email that the people surveyed were asked about whether they had experienced persistent symptoms following a Covid infection at some point—not whether they were experiencing those symptoms at the time they responded. He also said that the people taking part in both rounds of the survey had mostly been infected around the same time.
The original online version of the article carried the headline: “More Brits could avoid long Covid if they catch virus in warmer months of year”. This has been changed in the latest version at the time of writing to say: ”Long Covid may impact Brits less during warmer months – being outside could help”. A correction note has also been added, explaining that this change took place.
However, the latest version of the article still wrongly claims that the research found that “catching Covid-19 in the colder winter months may be a factor in whether some people find their symptoms persisting”.
What the research says
The Mirror article was based on the latest results from the REACT-2 survey, which asked people whether they’d previously had Covid, and whether they had persistent symptoms 12 weeks after infection.
The third, fourth and fifth rounds of the survey took place between September 2020 and February 2021.
The Mirror reported that, among those reporting a previous Covid infection, “37% had at least one lasting symptom 12 weeks later”. (When these figures were weighted to represent the population of England, they suggested a prevalence of about 5.75%.)
A sixth round of the survey took place in May 2021, which the Mirror said “saw prevalence drop to 22%” (the unweighted figure, which is not representative).
However, this only means that the proportion of people reporting having had persistent symptoms at some point during the pandemic was lower in May 2021 than it was between September 2020 and February 2021. It doesn’t take any account of when the original Covid infection happened.
These figures therefore don’t tell us anything about whether catching Covid during warmer weather makes you more or less likely to develop long Covid.
Photo by Marco Verch