If Covid-19 is a seasonal virus, why is it spreading during the summer? | Francois Balloux

Understanding seasonality can help us to work out when the pandemic is likely to be over

There is a paradox at the heart of Sars-Cov-2 transmission that has yet to be fully explored. While it's firmly established that the virus transmits best in winter, in common with most other respiratory viruses, the UK is currently experiencing a summer surge. There have also been major Covid-19 epidemic waves in regions such as South America and India outside winter. Why is this?

From the beginning of the pandemic, one major question was to what extent Covid would display a seasonal behaviour with higher case numbers in winter. Most respiratory viruses in circulation, including the flu and the four endemic coronaviruses contributing to common colds", display strong seasonal patterns, with most infections happening in winter in each hemisphere.