Jan. 10, 2024 – Some health care providers are warning that it can now take longer after COVID symptoms appear for tests to return a positive result.
Rapid tests that people typically use at home may not turn positive until the 4th day after symptoms appear. Earlier in the pandemic, many rapid tests returned positive results after 1 or 2 days of symptoms.
“It’s actually pushing back the time that people’s COVID tests are coming up positive. So some people are testing at day 1 and day 2 and saying, ‘Oh, it’s negative, I don’t have COVID,’” Elizabeth Hudson, DO, regional chief of infectious diseases at Kaiser Permanente Southern California, told the Los Angeles Times. “If they probably tested themselves a couple of days later, there’s a pretty good chance that it actually would turn out to be COVID.”
The CDC still advises that people who have any of 11 common COVID symptoms like a fever or cough to test immediately. If using an at-home rapid test, also known as an antigen test, anyone who gets a negative result should re-test after 48 hours, the CDC says. Another option is to take a more sensitive type of test called a PCR test.
For people who know they’ve been exposed to COVID but do not have symptoms, the instructions from the CDC for testing are slightly different. Absent of symptoms but with a known COVID exposure, people should wait at least 5 full days before testing.
For people with no symptoms who take two at-home rapid tests spaced 48 hours apart and the test is negative both times, the CDC recommends taking a third test another 48 hours later.
People who test positive should isolate and take other precautions, including contacting a health care provider to see if certain treatments, like taking antivirals, are needed, the CDC says. People who were exposed but don’t have symptoms should take precautions like masking for 10 full days, the CDC instructs.
One possibility for positive results taking longer may be due to the immunity levels people have accumulated at this point in the pandemic, from vaccinations or previous infections, Hudson told the Times. Going to a health care provider to get the more sensitive PCR test would likely return a positive result sooner for people who are infected, Hudson said.
Antigen tests are accurate about 80% of the time, compared to a 95% accuracy rate of PCR tests, according to FDA information published in 2022.
Free at-home COVID tests can still be ordered online at the government website COVID.gov. Adults who are uninsured or who have certain insurance like Medicare, Medicaid, coverage through Veterans Affairs, or coverage through the Indian Health Service may be eligible for free testing and free virtual medical appointments if they are positive through the Home Test To Treat program. The CDC also now offers a special webpage to search for nearby, no-cost COVID testing.
The latest CDC data shows 12% of all COVID tests were positive during the last 2 weeks of December.