The duration for testing positive for COVID-19 depends on the type of test used and individual factors such as immune function and severity of infection.

• Rapid antigen tests typically detect COVID-19 for about 5 to 10 days after symptom onset. Most people will test negative on rapid antigen tests after about 9 to 10 days.
• PCR tests are more sensitive and can detect viral genetic material for much longer, sometimes up to 3 months after infection, though this does not mean the person is still contagious. PCR tests may detect non-infectious viral particles lingering in the body.
• People with mild or asymptomatic COVID-19 usually stop testing positive on rapid antigen tests within about 9 days. Those with weakened immune systems or more severe illness may test positive longer.
• Generally, people are contagious for about 10 days after symptom onset or a positive test if asymptomatic. After that, even if PCR remains positive, the live virus is usually not present.
• Isolation guidelines now allow ending isolation after 5 days if symptoms are improving and fever-free for 24 hours, but precautions such as mask wearing are recommended through day 10.
• Retesting is not required to end isolation. Rapid antigen tests better indicate contagiousness than PCR during recovery.

In summary, expect to test positive on rapid antigen tests for about 5-10 days, while PCR tests can remain positive for weeks to months without indicating contagiousness.