Hays County’s health department has been doing contact tracing since it found its first coronavirus-infected patient, and this method has helped the department hold down the spread of COVID-19 in several instances.

“It has helped us to identify a couple of clusters that were linked back to people who tested positive and were asymptomatic,” said Dr. Eric Schneider, epidemiologist at the Hays County Local Health Department. “These people are the ones that typically expose t...