At what point do you cease to be positive for the virus that causes COVID-19? It depends on several factors, experts say, and the most important part is which test you use.
“A positive test can be short-lived or can persist for months,” Robert Amler, MD, dean of the School of Health Sciences and Practice at the New York Medical College in Valhalla, New York, told Verywell via email. “Different types of tests may or may not be persistently positive.”
There are two main types of tests COVID-19 that can be used to detect an active infection. Antigen tests, often called rapid tests, can rapidly look for the viral proteins called antigens and can be conducted at home. Molecular tests, like the polymerase chain reaction (PCR) test, look for pieces of the virus’s genetic material and are analyzed in a lab.
Whether you use a PCR test or a rapid test, the results are either positive or negative. They do not measure how much virus you may have in your body or how infectious you may be.
These tests, however, have different sensitivities.
PCR tests are more sensitive, and are able to detect the presence of the virus earlier. But they can also detect the presence of COVID-19 well past the point of when it’s contagious.
“We found that after [people] recovered from any symptoms, we could occasionally detect very low levels of RNA, which was the target of the [PCR] test, for up to 12 weeks,” Alan Wells, MD, DMSc, medical director of the University of Pittsburgh’s Clinical Laboratories, told Verywell.
According to a CDC review of 113 studies, COVID-19 is only contagious ranging from two to three days before symptom onset to eight days after.
“That’s why the CDC recommends that people be exempted from any sort of PCR surveillance testing for 90 days after a positive test,” Gigi Gronvall, PhD, senior scholar at the Center for Health Security at the Johns Hopkins Bloomberg School of Public Health, told Verywell. Gronvall works with the center’s COVID-19 Testing Toolkit. “I expect that that this guidance is probably going to change at some point with more information, but some people continue to test positive by PCR even after they’re clearly no longer infectious. For whatever reason, there is still viral genetic material hanging out in their nose.”
Rapid tests are less sensitive, but a person will probably still test positive for six or seven days after they are no longer having symptoms, Gronvall said.
Positive? Don’t Test Again
If you have gotten a positive result on a test, there is no point in testing any further.
“Health departments say if you test positive, don’t keep testing repeatedly in search of a negative test,” Amler said. “Any positive test is a positive result, so you will just be wasting scarce test kits.”
The only time to retest is if you test negative after you have been exposed to someone with the virus or if you have symptoms. It can take time for the virus to build up to levels that are detectable.
“You want to test on day three and five or day four and day six after exposure, just to make sure you are negative,” Wells said.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
