Instagram co-founders Mike Krieger and Kevin Systrom have teamed up to launch a new COVID-19 website that tracks contagion levels across U.S. states.

Called Rt.live, the tracking service uses a data analysis algorithm to track the “effective reproduction number” of the coronavirus to allow users to see how many secondary infections are likely to occur from a single infection in a specific area.

The effective reproduction number, abbreviated Rt, is a scientific measurement of the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection. Rt1 is the important number on the scale. Any figure below one means that a given virus is likely to die out in a population, whereas figures above 1 means that the virus is still spreading. The higher the number, the higher the infection rate.

In essence, Rt1 is the rate where one person with the virus may infect one other person, the baseline for a virus to spread in a community. Rt1.7 — currently the highest rate on the chart, for North Dakota — means that every person with the virus is expected to infect 1.7 other people.

In addition, the site also allows for filtering based on regions and states that currently have no shelter-in-place rule.

“We built Rt.live because we believe Rt — the effective infection rate — is one of the best ways to understand how COVID is spreading,” Krieger told TechCrunch. “It was great to work together again — we were able to take it from idea to launch in just a few days because of all our history & shared context.”

Both Krieger and Systrom, who sold Instagram to Facebook Inc. in 2012, left the parent company in September 2018, citing possible plans for a new startup. A report from the New York Post April 18 said Systrom quit because of many disagreements with Facebook Chief Executive Mark Zuckerberg over the direction of Instagram, including pushing advertising on users.

Image: Rt.live