4 May 2021:
Coronavirus is likely a seasonal virus, but will not vanish during summers, reveals a study.
A team of researchers from Harvard University in the US and Chinese Academy of Medical Sciences, Beijing, conducted a visual inspection of world maps and found that coronavirus disease 2019 is less prevalent in countries closer to the equator, where heat and humidity tend to be higher. The findings, published in the journal Scientific Reports, showed that countries are likely to see a decline in new Covid-19 cases during summer and a resurgence during winter.
Our results are consistent with the hypothesis that heat and sunlight reduce the spread of SARS-CoV-2 and the prevalence of Covid-19, which was also suggested by most of the previous studies examining the same hypothesis with different data and approaches,” said the team, including David E. Bloom, from Harvard’s T.H. Chan School of Public Health.
However, the results do not imply that the disease will vanish during summer or will not affect countries close to the equator. “Rather, the higher temperatures and more intense UV radiation in summer are likely to support public health measures to contain SARS-CoV-2,” the researchers said.
The team examined the relationship between the number of Covid cases in 117 different countries and the latitude of the country from the beginning of the pandemic until January 9, 2021. They found for every one degree increase in the latitude of a country, there was a 4.3 per cent increase in the Covid cases per one million people.
The results imply that a country, which is located 1,000 km closer to the equator, could expect 33 per cent fewer cases per million inhabitants. “Since the change in the earth’s angle towards the sun between equinox and solstice is about 23.5 degrees, one could expect a difference in cases per million inhabitants of 64 per cent between two hypothetical countries whose climates differ to a similar extent as two adjacent seasons,” the researchers said.