This is the job of a contact tracker in the US.

The Los Angeles County Department of Public Health is trying to control the coronavirus pandemic by implementing a contact tracing program. Gonzalo Alvarado talks to one of the thousands of people who are part of this tracking program. Lupita Leyva makes it clear that when they call they will never ask for the person's social security number, bank accounts, payments, or immigration status. It is difficult for people with coronavirus to want to share information about the people with whom they have been in contact, so an incentive has been created that is giving good results. Los Angeles County reports nearly half of all positive COVID-19 cases in California.