COVID-19 rates have spiked in the winter months in the Northern Hemisphere and in summer months in the Southern Hemisphere. A new study suggests that the current winter peaks result from relaxing control measures — not changing climatic conditions.
Scientists suggest that the rate of infections with SARS-CoV-2, the virus responsible for Covid-19, during the winter is more likely to be influenced by relaxed control measures than any climatic conditions, such as cold weather.
The research, published in the journal Nature Communications, may be valuable in understanding how best to protect against Covid-19 as the disease potentially shifts from pandemic to endemic status.
Study co-author Gabriel Vecchi, a professor of geosciences at the High Meadows Environmental Institute, at Princeton University, in New Jersey, says:
“The influence of climate and weather on infection rates should become more evident — and thus a potentially useful source of information for disease prediction — as growing immunity moves the disease into endemic phases from the present epidemic stage.”
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Many viruses are more active in winter than summer, particularly in temperate climates.
Scientists are beginning to understand why this might be, and the reasons are different for each virus.
In temperate climates, these reasons concern how well the virus survives at a particular temperature and humidity level, the capacity of the human viral defense system, which includes the nose and immune system, and how humans behave in cold temperatures.
The incidence of Covid-19 greatly increased during the winter months of 2020 to 2021 in the Northern Hemisphere. But it has been unclear whether this was due to the changing weather — as with seasonal viral illnesses such as influenza — or some other factor.
In the summer of 2020, the authors of the present study, a team from Princeton, simulated an outbreak of a coronavirus in New York during winter. With this simulation, they were able to predict the effects of climate on SARS-CoV-2.
