For those who have been in close contact
Klamath County Public Health notes
When exposed to COVID-19 by someone outside of your home, your last exposure is the last time you were with that person. When exposed to COVID-19 by someone inside your home, your last exposure is the last day of that person's isolation or quarantine.
Quarantine is used to keep someone who might have been exposed to COVID-19 away from others. Quarantine helps prevent spread of disease that can occur before a person knows they are sick or if they are infected with the virus without feeling symptoms. People in quarantine should stay home, separate themselves from others, monitor their health, and follow directions from their state or local health department.