We're tracking the latest on the coronavirus outbreak and the global response. Sign up here for our daily newsletter on what you need to know.

Instagram’s founders, who have been mostly out of the public eye since leaving Facebook Inc. in 2018, introduced a website that gives live state-by-state updates on the spread of Covid-19.

RT.live uses a statistic called an effective reproduction number, which tracks the average number of people who catch the virus from a single infected person.

“If it’s above one, that means it’s growing very quickly, and if it’s below one, that means things are under control,” Kevin Systrom, the co-founder and former chief executive officer of Instagram, said in an interview on Bloomberg Television. “We’re trying to take what is a complex topic and boil it down to a simple number that anyone can view from their home.”

According to the RT.live site, the data come from The Covid Tracking Project, a volunteer organization started to help collect and visualize testing and infection rates for Covid-19.

While the pandemic is global, Systrom said it’s more useful to look at the infection rate from a local angle. According to the ranking, Vermont is much safer than Georgia, for instance. He hopes RT.live helps citizens understand whether they are in danger as parts of the economy reopen. “That’s why this dashboard is so important -- because it gives you live insight into the effects of the choices we all make,” he added.

Systrom and Mike Krieger, the Instagram founders, left Facebook in late 2018 after clashing with CEO Mark Zuckerberg. While neither man has a background in health or epidemiology, the same statistical modeling that applies to fast company growth might also be useful for tracking virus growth, Systrom said.

He doesn’t expect to turn the new site into a company, though. “We’ll see where it goes,” he said.

— With assistance by Candy Cheng