Some of the research described in this article has been published on a preprint server but has not yet been peer-reviewed by experts in the field. As Covid-19 infections soar across the U.S., some states are tightening restrictions and reinstituting quarantine measures to slow the virus’ spread. A model developed by MIT researchers shows a direct link between the number of people who become infected and how effectively a state maintains its quarantine measures. The researchers described their model in a paper published in Cell Patterns in November, showing that…