How to get free or low-cost Covid tests this holiday season — and use them most prudently

The third holiday season since the pandemic started is approaching, and Covid remains a persistent presence. More than 300 people die of the coronavirus every day, on average, according to NBC News' tally.

Testing remains a crucial tool to identify cases and curb spread. But finding low-cost tests and interpreting the results aren't always simple.

Here's the latest guidance from the Centers for Disease Control and Prevention and the Food and Drug Administration, as well as expert advice, about how to get tests without paying out of pocket, check when an at-home test expires and interpret a negative result if you have symptoms or known exposure.

Private insurance and Medicare cover eight at-home tests a month

Since January, the Biden administration has required private insurers and Medicare to cover up to eight at-home tests per month. People with private insurance can order the tests at in-network pharmacies or submit claims to be reimbursed for tests they buy at other stores or out-of-network pharmacies. People with Medicare can search online for a list of providers that offer free tests.

PCR lab tests are also fully covered through private insurance and Medicare.

Free at-home tests from the government are no longer available

The federal program that distributed up to 16 free at-home tests to households through the mail ended Sept. 2 because of a lack of congressional funding.

How to find free testing sites near you

Some sites that provided free rapid or PCR tests earlier in the pandemic have closed, but the Department of Health and Human Services has an online search tool to find nearby sites still offering free or low-cost tests. Most of the locations are pharmacies like CVS and Walgreens, but the site can also direct you to your state health department's website, which may offer additional options.

Once the government's public health emergency declaration expires, testing costs will probably go up

The declaration was last renewed in October, and it could end sometime in 2023. After that, Medicare beneficiaries will most likely have to pay the full cost of at-home tests but should still get clinical diagnostic testing covered, according to KFF, a nonprofit health think tank. For people with private insurance, testing costs will be subject to the particulars of their plans, but they are unlikely to be covered in full.

Rapid tests can expire, but many shelf lives have been extended

Different tests have different shelf lives, but many of the original expiration dates have been extended since the tests were authorized.

In such cases, the manufacturer has provided evidence to the government that the tests give accurate results longer than was known when they were created.

Abbott’s BinaxNOW at-home test, for example, says it has a shelf life of 15 months, but the expiration dates of many batches have been extended by three to six months. The government-distributed tests from iHealth Labs, meanwhile, last one year, but most of their shelf lives have been extended four to six months. Flowflex at-home tests have a shelf life of 19 months, with extensions of six months.

To check whether the expiration date of your particular test has been revised, click on the relevant link on the FDA's list and look up the lot number.

When to test if you've been exposed or feel ill

If you have symptoms, take a test immediately. If you were exposed to someone who tested positive but you feel healthy, test after five full days.

The FDA recommends that people with known exposures who test negative take second tests 48 hours later. If they are negative again, test a third time after another 48 hours.

"We know antigen-based tests, you have to repeat them. They're not a one-and-done test," said Dr. Susan Butler-Wu, an associate professor of clinical pathology at the University of Southern California.

If you are exposed within 30 days after having testing positive for Covid, you don’t need to test unless you develop symptoms, according to the CDC. If it has been less than 90 days since your last Covid infection, use a rapid test, because PCR results can stay positive for up to 12 weeks.

What to know about the accuracy of at-home tests

PCR tests are generally more sensitive and accurate than at-home tests, but the results can take at least 24 hours — and often several days. At-home tests (also known as antigen tests), meanwhile, rarely give false positives but can give false negatives, even if someone is symptomatic. That's especially likely in the early days of an infection.

Scientists aren't sure why that is. One theory is that the immune response leads to symptoms before the virus has a chance to replicate to detectable levels. That may cause people to feel tired, achy or sniffly before they test positive.

For other people, Covid tests never come back positive even though they feel sick and were exposed to the virus. It's possible that those people have unrelated infections or their immune systems did a swift job of vanquishing the virus before it replicated widely enough to register on a test.

People who are elderly or immunocompromised should still seek out PCR tests if they feel sick or were exposed to Covid and get negative results on at-home tests, said Dr. Sheldon Campbell, an associate professor of laboratory medicine at the Yale School of Medicine. That's because those groups are eligible for treatments like Paxlovid in the days after they test positive.

"You don't want to wait two days, get a positive and realize you should have been treating for two days," he said.

Your test result could be a good indicator of contagiousness

Campbell said testing positive on an at-home test is a pretty good indicator you're infectious. But Butler-Wu cautioned that it’s still possible to be contagious and test negative on an at-home test or to test positive and not spread the virus to others.

"At the end of the day, there is no infectiousness test for Covid. There has never been, and there still isn't," she said.

It is well established, however, that people are more likely to be infectious at the start of their illnesses. An August study found that 65% of people with Covid shed infectious virus five days after their symptoms started but that just 24% were still doing so after a week.

How long you're likely to test positive

If you are mildly ill, the CDC recommends isolating for at least five days after your positive test or the start of symptoms, then ending isolation if you test negative or if symptoms have resolved or are clearing up. If your symptoms haven’t improved much or you still have a fever on day five, the agency advises continuing isolation until you are fever-free for 24 hours without medication.

People with moderate or severe illness — characterized by shortness of breath or hospitalization — should isolate through day 10.

"Typically, people are positive for about seven days after their symptoms" start, Campbell said. "Some people can go longer — rarely more than two weeks."

In one small study, just 25% of people with Covid were negative on rapid tests on day six of their illnesses, but all the participants tested negative after two weeks. In a study of college athletes with Covid, meanwhile, 27% still tested positive one week after their first positive tests.

Campbell said scientists are still investigating why some people test positive for more than two weeks.

"People who are antigen test-positive beyond two weeks are in some fashion not having good immunity to the virus," he said.