If a staff member has spent a total of 15 minutes within six feet of a person who tested positive for COVID-19 over a 24-hour period starting from 2 days before illness onset (or, for asymptomatic patients, 2 days prior to test specimen collection), the staff member should quarantine for 14 days per CDC guidelines.
If a person who was in close contact with someone who tested positive gets tested and receives a negative test result, he/she should still quarantine for 14 days after exposure, according to the Pennsylvania Department of Health.
Remind staff who have tested positive or have been ordered to quarantine that they are entitled to up to two weeks of paid sick leave at their regular pay rate per Families First Coronavirus Response Act.
You can require that a staff member tests negative before returning to work. A study by Johns Hopkins found that getting tested too soon might lead to false negatives, and recommends waiting between two and five days after exposure before getting tested. (Source)