You can test positive for COVID-19 for different durations depending on the type of test used and your illness severity. PCR tests, which are highly sensitive, may show a positive result for up to three months after infection because they detect viral particles that can linger, even when you are no longer contagious. In contrast, rapid antigen tests generally detect active infection and usually stop showing positive results after about 9 to 10 days, typically as your symptoms improve and your infectiousness decreases. Most people with mild or asymptomatic cases test negative on rapid antigen tests after around 9 days, while some may continue to test positive up to 14 days or slightly longer in particular cases. People with moderate to severe illness or who are immunocompromised may test positive for longer periods. The contagious period typically ends within about 10 days after symptom onset or positive test in asymptomatic cases. In summary:

• PCR test positive: up to 3 months (detects non-infectious viral remnants)
• Rapid antigen test positive: generally up to 9-10 days, sometimes up to 14 days
• Contagiousness tends to end after about 9-10 days for mild cases
• Isolation guidelines usually recommend at least 5 days of isolation, with masking continued through day 10 after symptom onset or positive test

These durations can vary person to person, and testing strategies differ depending on the context and symptoms.