This new online tool lets you calculate Covid-19 risk

If you were to find yourself in a group of ten people in the US capital Washington today, the risk that one person has Covid-19 would be 18 percent. The equivalent figure in Paris is 32 percent.

That's according to a dashboard developed by a team of US scientists that allows people to assess the risk of attending gatherings where they live using real-time infection data.

The tool, developed by a team at the Georgia Institute of Technology, provides district-level Covid-19 transmission rates for the United States and selected European countries and can be viewed here: https://covid19risk.biosci.gatech.edu/

The team behind it published a paper about their work in the journal Nature Human Behaviour this week, where they wrote it "provides data-driven information to help individuals and policymakers make prudent decisions (for example, increasing mask-wearing compliance and avoiding larger gatherings)."

It estimates the probability that at least one Covid-19 positive person will be present at a given event in a given district or county after the user inputs the size of the gathering using a slide tool.

Of course, the actual risk of transmission depends on the type of gathering -- outdoor versus indoor and whether masks are used -- but Joshua Weitz, who co-developed the dashboard, said they had side-stepped this issue.

"Precisely because of these factors, we have focused deliberately on the question: what is the risk that one (or more) individuals have Covid-19 in events of different sizes?"

Epidemiologists believe that for every confirmed case in the United States, there are about 10 times more that haven't been detected.

The tool, therefore, factors this in, but also allows the user to turn the dial down to a ratio of 5:1 since testing rates are increasing in some areas and this may give a more accurate answer in those places.

Weitz said the model assumed that a person remained positive for 10 days, and he and his colleagues plan to add more countries in the future.

It comes as US cases are hitting new peaks, with 144,000 new cases recorded Wednesday and hospitals under pressure.

New York state has announced that any establishment with a liquor license, including bars and restaurants, would have to close at 10:00 pm beginning Friday. The rule will also apply to gyms.

Cases are so high in El Paso, Texas that the state has requested a military medical center be converted for the intake of non-Covid patients in order to free up space in hospitals.