Quarantine refers to what you do after being exposed to someone who has COVID-19, and isolation refers to what you do after having tested positive for COVID-19 yourself. In either case, you should stay at home to help prevent the spread of infection. When isolating or quarantining, you should separate yourself from other people in your household by staying in a separate room and using a separate bathroom if possible. If this is not possible, make sure everyone is wearing a mask and socially distancing at all times when around each other.
You should quarantine if you have been in close contact with someone who has tested positive for COVID-19 and you are not up to date on your vaccinations and have not had COVID-19 in the past 90 days. Close contact means that you were within 6 feet of someone for a cumulative total of at least 15 minutes over a 24-hour period. Generally, after an exposure, quarantine lasts at least 5 days and is followed by an additional 5 days of wearing a mask around others.
You should isolate if you have tested positive for COVID-19, or if you have symptoms that are consistent with COVID-19 (ie, nasal congestion, runny nose, sore throat, cough, fatigue, fever, or shortness of breath) and are awaiting test results. Generally, for people who test positive for COVID-19, isolation lasts for at least 5 days after symptom onset and can be ended when symptoms are improving and fevers have resolved for 24 hours. Isolation is generally followed by additional days of wearing a mask around others until a total of 10 days have passed from symptom onset.