A group of researchers created a model by which it is possible to find out, according to the city or country in which you live.
If ten people gather around a table this Thursday in Paris, the risk that at least one of the guests has coronavirus is 32%. ANDn Washington, it is 18%.
In the American county of Walsh, in Dakota of the North, it is more than 99%. In Prague, 58%.
The calculation is simple and is based on real-time data on the pandemic of covid-19, clearly presented by a website that has grown in popularity since it went live in July.
Created by researchers at Georgia Tech University, its methodology was validated Monday with a publication in Nature Human Behavior, one of the prestigious Nature magazines.
The address is https://covid19risk.biosci.gatech.edu/ (in English), but it was a victim of its own success on Thursday, when it showed error messages in the face of the influx of connections.
Researchers calculate risk based on the official number of new cases reported each day in a given location (by county in the United States or by department in France).
The model also takes into account the fact that the actual number of infections is 5 to 10 times greater than the number of positive tests registered, and the user can calculate the risk according to these two hypotheses, 5 or 10.
The site allows estimating, in addition to the United States and France, Spain, the United Kingdom, Italy, Switzerland, Austria, the Czech Republic and Ireland.
In the United States, the director of the Centers for Disease Control and Prevention (CDC) said in the summer that the tests probably detect only one in 10 cases.
The figures cited at the beginning of this article are based on the estimate that the actual number of infections is 10 times higher than officially recorded. If we estimate that it was only five times higher, the risk of having a positive person at a Parisian dinner of 10 people drops to 18%, 10% in Washington and 94% in Walsh.
You can also select the size of the event you plan to participate in: 10, 25, 50, 100 or up to 5,000 people.
Today, in many places in the United States and Europe, se exceeds 50% probability to be in the presence of an infected person if you share space with 50 people.
With 50 people, at a wedding or in crowded bars – if they were open – the risk of at least one being contaminated it would be 86% in Paris and 99% in the Rhône, also in France.
The site takes a conservative approach: it assumes that a person stays positive for 10 days, its creator, Joshua Weitz, tells AFP.
Researchers estimate that a person is highly contagious for less time, on the order of 5 to 6 days, and that the rest of the time it is less so or not so at all, despite the residual presence of the virus.
The model also does not take into account that an infected person is more likely to stay home after symptoms appear.