After the test result is positive, you may continue to test positive for some time. You may continue to test positive for antigens for a few weeks after the first positive result. You can continue to test positive for NAAT for up to 90 days. Reinfections can occur within 90 days, which can make it difficult to know if a positive test indicates a new infection.
Consider seeing a health care provider if you have any questions or concerns about your individual circumstances. More generally, people are likely to test positive for COVID-19 at home for about six to 10 days, Dr. Stephen Kissler, a postdoctoral fellow at Harvard's T, H. Chan School of Public Health, from the Department of Immunology and Infectious Diseases, told TODAY.
Home antigen tests can test positive for 10 days, or even longer, up to 14 days, according to The New York Times. Public health experts have said it's been difficult to understand what that means in terms of contagion, since rapid tests can't always predict accurately. In general, most people who become infected still don't test positive for antigens 10 days after symptoms appear.