How to get the most out of your Covid test at home

As Covid has become a regular part of respiratory virus season, community testing centers and drive-through sites where you could determine if it’s the source of your sniffles have all but disappeared.

However, home tests are still a valuable tool to protect yourself and others from the virus, and they remain widely available in pharmacies and supermarkets.

Here’s what you need to know about how these tests work, how to get them, and when to take one.

Do rapid tests still work?

Yes. Even with a new variant, JN.1, dominating cases nationwide, rapid tests should be able to accurately determine whether you are contagious. That’s because rapid tests detect a protein in the virus, rather than the spike protein on the surface of the virus that has changed between variants, said Aubree Gordon, an infectious disease epidemiologist at the University of Michigan. However, there is a catch: you have to test at the right time.

So when should I test?

Experts recommend testing as soon as you develop symptoms and, if possible, throughout your illness. But if you’re low on testing, you may want to wait about three to four days after you develop symptoms. “If it were me and I knew I only had one test, and I became symptomatic this morning, I wouldn’t use that test today,” said Dr. Michael Mina, a former Harvard epidemiologist and now eMed’s chief science officer. a healthcare technology company offering Covid testing and virtual care. “I would use it the day after tomorrow.”

If you are negative, test again 48 hours later to rule out a false negative. If you’ve been exposed to someone and don’t develop symptoms, the Food and Drug Administration advises wait five full days to test.

If you are going to spend time with people who are at high risk for severe Covid-19, such as someone in a nursing home, you should test immediately beforehand to determine whether or not you have been exposed. It’s best to stay home if you have symptoms, such as a runny nose, sore throat, or chills, regardless of what the test says.

The tests are expensive. Where can I get more for free?

Experts acknowledged that it has become harder to get free tests since the Covid-19 public health emergency ended in 2023 and many insurance companies have stopped covering the costs. But you can still access it.

You can order a maximum of eight free home tests from the federal government per household CovidTests.gov. Another option for free testing and treatment is the National Institutes of Health’s Home Test to Treat program, where Dr. Mina is involved. You may be eligible for free testing through the program if you are uninsured, considered “underinsured,” enrolled in Medicaid or Medicare, or receiving care through the Department of Veterans Affairs or Indian Health Services.

Medicaid and the Children’s Health Insurance Program will cover at-home tests through September 2024. Although Medicare generally does not cover over-the-counter products, it should not cost you anything if you are on Medicare and a doctor orders a PCR or rapid test for you. Some Medicare Advantage plans may offer coverage for at-home testing. You can also use a health savings account or flexible spending account to pay for them.

Some public health centers making free or low-cost Covid testing available to people who are uninsured or members of underserved communities. And some cities are still handing out free Covid tests at schools and public libraries.

Should I use an expired test?

Probably not, because it won’t be that accurate. But make sure your test kit is actually expired. The FDA has one list of tests with extended shelf life dates. To check this, look for the lot number on your test box.

If you use an expired test and “it comes back positive, believe it,” said Dr. Mina. But you should not use a negative result from an expired test to rule out an infection.

I got a positive result. Do I still have to report it?

A positive result means that you are infected and probably contagious. You should notify your close contacts and isolate yourself to avoid exposing more people. It is also good practice to report your positive result, which can help public health officials tailor their guidance and allocate resources appropriately. This can be done via the NIH website MakeMyTestCount.org. (Tests performed at a doctor’s office, in a lab, or during a telehealth appointment are automatically reported.)

Could my positive result be wrong?

False positive results are “quite rare,” said Dr. Gordon. But if you want some peace of mind, she added, you can test again with a different kit or ask your doctor for a PCR test, which can pick up smaller amounts of virus than a rapid test.

Does the darkness of your Covid test line correspond to how sick you are?

If you test for your infection every day, you may notice that the pink test line changes from faint to bright before fading again. Researchers have found that the appearance of the test line tends to indicate this how much viral protein is present. And if you have a lot of virus in your body, you’re more likely to spread it to other people, too, Dr. Gordon said.

But the darkness of the line can also vary depending on how you take the swab, how old the test is, whether you have been vaccinated or previously infected or even what time of day you test.

How long are you contagious after you test positive?

You may be shedding virus particles for a day or two before your first sniff; this viral shedding may peak two or three days after you develop symptoms. You are less likely to transmit your infection later during your illness. Although some people test positive for longer, most will test negative by day 10.

Ideally, you should test throughout the course of your infection until you’re negative, says Zoë McLaren, an associate professor at the University of Maryland, Baltimore County. This way you know when it is safe to see other people again.

I had all the classic Covid symptoms, but I never tested positive. Did I do it wrong?

It is possible that you did not perform the smear test properly, or that you have had another illness. After all, we are in the middle of RSV and flu season.

But the latest variant is so contagious that if someone you live with has Covid, there’s a good chance you’ll become infected, said Dr. Marc Sala, co-director of the Northwestern Medicine Comprehensive Covid-19 Center in Chicago. If you have been previously vaccinated or infected, your immune system will recognize the pathogen and take action to fight it, causing you to develop symptoms. But the virus cannot build up high enough in your nose to be registered on a home test, meaning that even if you feel sick, your test may remain negative and you are most likely less contagious or possibly not contagious at all.