The new coronavirus is seasonal and spreads under certain climatic conditions, suggests a new study.
The researchers found that the areas affected at the start of the epidemic were in a similar band of north latitude, such as Wuhan and Daegu in Asia; Milan and Paris in Europe; and Seattle in the United States.
Among these cities, cold temperatures and relatively low humidity from January to March were also linked.
This seems to imply that the virus behaves similarly to seasonal respiratory viruses such as the flu.
The team, from the University of Maryland School of Medicine, says its maps can help scientists and policy makers predict where and when epidemics will occur so they can stop the deadly disease in its tracks before it’s too late.
From November 2019 to March 2020, eight cities that had a “substantial” spread of coronavirus were all in a narrow band of latitudes between 30 ° N and 50 ° N (in the green band and the black circles)
This combination of low temperatures exposes Central Asia, caucuses, Central and Eastern Europe, the United Kingdom, the northeast and west-central United States, and British Columbia (all in the green band ) at greatest risk of spread during fall and winter
For the study, published in JAMA Network Open, the team collected climate data from 50 cities around the world between January 2020 and March 2020.
Eight cities with “substantial” spread of the virus – Daegu, South Korea; Madrid, Spain; Milan, Italy; Paris, France; Qom, Iran; Seattle, United States; Tokyo, Japan; and Wuhan, China – were compared to 42 cities little or not affected by the virus.
“Substantial” transmission has been defined as a country reporting at least 10 deaths from COVID-19, the disease caused by the virus, as of March 10.
Climate data, such as temperature and humidity, comes from new analysis from the European Center for Medium-Term Weather Forecast ERA-5.
From November 2019 to March 2020, the eight cities that had grown considerably were all in a narrow band of latitudes between 30 ° N and 50 ° N.
However, COVID-19 has failed to spread as widely among cities north of this band, such as Moscow, Russia, which is located 56.0 ° N, and to the south as in Bangkok, Thailand, sitting at 13.7 ° N.
Cities with high diffusion also had low specific humidity levels, or the amount of water vapor in a unit of humid air in grams per kilogram (above)
The researchers then looked at the 2m temperature, which is the temperature near the Earth’s surface, where most human activity takes place.
The results showed that in January 2020 in Wuhan and in February 2020 in the other seven cities, the average temperature in airport weather stations was between 39F (4C) and 48F (9C).
Average temperatures 20 to 30 days before the first community death in each city were about the same, ranging from 37F (3C) to 48F (9C).
Cities also had similar amounts of specific humidity (Q), or the amount of water vapor in a unit of humid air in grams per kilogram.
“Having low average temperatures and a low Q tightly clustered cities with significant epidemics as of March 10, 2020, compared to cities that had no COVID-19 cases,” the authors wrote.
The team says the results show why the risk of community spread affected affected areas such as Central Asia, caucuses, Central and Eastern Europe, the United Kingdom, the northeast and the west center from the United States and British Columbia in winter.
It also shows that the coronavirus behaves similar to a seasonal respiratory virus, like the flu, peaking in cold weather and dying out in warmer weather.
In addition to prolonging the life of the virus, cold temperatures and low humidity can also affect the speed at which it reproduces in the nasal cavity and altered immunity, allowing the virus to spread and move throughout the body.
“All of this indicates a potential direct association between temperature and environmental survival and spread of SARS-CoV-2,” the authors concluded.
“Using weather modeling, it may be possible to estimate the regions most likely to be at higher risk of significant community spread of COVID-19 in the coming weeks, which will allow efforts to focus public health surveillance and containment. “
In the United States, there are more than two million confirmed cases of the virus and more than 112,000 deaths.