If you test positive for COVID-19, you should follow your doctor's and the Centers for Disease Control and Prevention's (CDC) instructions on isolation. Generally, most people who become infected still don't test positive for antigens 10 days after symptoms appear. Home antigen tests can test positive for 10 days, or even longer, up to 14 days, according to The New York Times. The CDC recommends that if your test is positive and you are in the midst of an active COVID-19 infection, you should wait until your isolation period ends before getting vaccinated.
If you're not sure if your test is actually positive or not, check with your doctor, have a PCR test, or have a second rapid test the next day (assuming you actually have COVID-19 in the meantime). CDC research indicates that most people with COVID-19 can expect to see a positive result for five to nine days. As long as you continue to test positive for a rapid test at home, you should continue to be considered potentially contagious. If you're concerned about how long you've been testing positive, see a health care provider for guidance on your individual situation.
A positive antigen test could consist of detecting leftover viral residues, which could include dead viruses or destroyed viruses. But there's no perfect study that shows how likely it is that a positive test in a rapid test will result in the spread of enough virus that you can actually infect another person. With PCR tests, which look for the genetic material of the virus, people can test positive for longer. Getting a quick test can also help you determine if you should spend time with people who are particularly vulnerable to severe symptoms of COVID-19, such as those with certain underlying health conditions.
Even with a rapid test, which detects molecules on the surface of the virus rather than the genetic material of the virus, it's not uncommon for people to test positive for up to 14 days, especially for people who aren't vaccinated.If you have any symptoms that could indicate the presence of COVID-19, you should get a home test right away, according to the CDC. Isolation can be interrupted at least 5 days after the first positive viral test (day 0 is the date the sample was collected for the positive test and day 1). In addition, you can end your isolation after just five days if you never had symptoms, but you must continue to wear a mask for a total of 10 days.