Got the sniffles? Worried about that night out in a crowded dance club? Or maybe you just want to visit grandma but are concerned about her risk, even though you’re vaccinated.

At-home rapid COVID-19 tests — which allow you to swab your own nose and get the results in minutes — can be a useful and reassuring way for both the vaccinated and unvaccinated to navigate the ongoing pandemic.

With the availability of vaccines for all people 12 years and older in the United States, it may be hard to imagine why anyone would still need a home test for COVID-19. But the coronavirus isn’t going away anytime soon, and a rise in infections this fall among the unvaccinated appears inevitable as a new, highly infectious variant called Delta spreads around the world.

In most cases, regular home testing isn’t necessary for someone who is fully vaccinated. The current crop of vaccines available in the United States have been shown to be effective against the variants, including Delta. But no vaccine is 100% protective, and breakthrough infections, though rare, continue to occur.

A home test can offer reassurance to a vaccinated person who has traveled recently or spent time in a crowded bar. It can be used more frequently for families with young children who aren’t yet eligible for vaccination. Home tests are also useful for anyone with an at-risk family member or for people who, for whatever reason, remain unvaccinated.

“The most important aspect of these tests is the rapid result,” said Dr. Michael Mina, an assistant professor of epidemiology and immunology at the Harvard T.H. Chan School of Public Health. “Waiting two to three days for laboratory test results isn’t ideal when you need results quickly to make decisions about going to school, work or a social gathering.” Mina, who championed the use of rapid testing at the height of the pandemic, said that more people should think about using at-home, rapid testing to keep children, the old and at-risk, and the unvaccinated safer in the coming months.

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“As long as the virus is raging in other parts of the world, the risk is too high to completely let down our guard with testing,” Mina said. (Mina consults with a new home-testing company that doesn’t yet have any products on the market.) “Unvaccinated people will continue to spread the virus, which happens often without showing any symptoms. And while it’s much less likely, even vaccinated individuals can become infected.”

Here are some scenarios where a rapid home test might be useful for vaccinated or unvaccinated people.

— For unvaccinated children, who could be tested periodically before going to camp or school or right before a birthday party.

— To regularly check and protect the health of a babysitter who spends time with your unvaccinated children or a home-health aide who is caring for a high-risk individual.

— As an added precaution for a vaccinated person who wants to spend time with a grandparent or someone who is immune compromised. (An unvaccinated person shouldn’t spend time indoors with a person at high risk.)

— After traveling on an airplane or spending time in an airport or a crowded bar. (While a vaccinated person does not need to be regularly tested after travel, a home test could be used as a precaution after spending extended time indoors with people whose vaccination status isn’t known.)

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—- To be sure a cough or sniffle is just allergies or a common cold rather than COVID-19.

— To test houseguests before a dinner party or overnight stay, if someone in the group is unvaccinated or at high risk.

— For guests at weddings or other large gatherings if they can’t provide proof of vaccination.

There are two types of home tests that are authorized for use in the United States that give you results on the spot: a rapid antigen test, and a rapid molecular test.

Rapid antigen tests are the least expensive (about $12 per test) and are available in retail stores and online. (They typically aren’t covered by insurance.) The BinaxNOW test, made by Abbott, contains two rapid antigen tests per box and costs around $24. To take the test, just swirl the swab in both nostrils and place in a special card. After 15 minutes, the result reads much like a pregnancy test: two pink lines indicate you’re positive for COVID-19. The QuickVue At-Home test, from Quidel, is similarly priced. After swabbing your nose, dip the swab in a solution in a test tube, and then in a test strip. You’ll get results in about 10 minutes.

The rapid antigen tests are less reliable for finding COVID-19 in people with low viral loads compared to the “gold standard” PCR tests you’d get from a health care provider. One study found that a rapid home antigen test had a 64% chance of correctly spotting the virus in people with symptoms who had tested positive on a PCR test. (The test caught only about 36% of those who had the virus but didn’t have symptoms.)

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But don’t be dissuaded by those numbers. The affordable rapid antigen tests provide a reliable quick check to identify people with infectious levels of virus. For example, let’s say you want to invite friends into your home who are unvaccinated or who have an unvaccinated child. Before hosting an indoor gathering, you can reduce the risk of asymptomatic spread and infection by 90% or more if all guests use a rapid antigen test within an hour before the event, said Mina. Rapid testing can also be used as an added layer of protection before spending time with people who are at high risk of complications from COVID-19, such as those with immune problems or undergoing cancer treatments. Neeraj Sood, a professor and vice dean for research at the University of Southern California and director of the COVID Initiative at the USC Schaeffer Center, said that even though he’s vaccinated, he would use rapid testing to take extra precautions around such people.

“If I was going to hang out in an enclosed space with a friend who’s getting chemotherapy and hasn’t gotten the vaccine, then I would do two tests,” Sood said. He would take one rapid antigen test three or four days before visiting the friend, and another test the same day of the visit. “If both are negative, I’m very confident I don’t have COVID, and I’m not going to transmit it to my friend,” he said.

Rapid testing could also be used to make a small family indoor gathering or a child’s birthday party that included a mix of vaccinated and unvaccinated people safer. “If you put that extra layer in of home testing, I think you’re all making each other more safe,” said Irene Peterson, a professor of epidemiology and health informatics at University College London. “Or you could decide not to have the party.”

If you want more certainty than a rapid antigen test can provide, you can consider a more costly rapid home molecular test. These tests work by detecting the virus’ actual genetic material (RNA) and amplifying it to determine if you’re infected. A home rapid molecular test works nearly as well as the PCR tests given at testing centers that are processed by a laboratory, but they are also more expensive than the home antigen tests. Lucira makes a highly accurate molecular test for $55 that uses nasal swabs and a battery-powered processing unit that provides results within 30 minutes. When would the cost of a rapid molecular test make sense? Families planning a wedding may have loved ones who aren’t vaccinated. (Some people are not fully vaccinated because of health conditions or because they had a bad reaction to the first dose.) For wedding guests who can’t provide a vaccination card or a lab-based negative PCR test result taken within 36 hours of the event, you could ask them to take a home-use rapid molecular test. (You’ll have to work out who will pick up the tab for the test.)

Mina noted that for a large event like a wedding that stretches over a few days, a molecular test would be more reliable than a rapid antigen test because it can detect an early infection as much as 48 hours before an antigen test will turn up positive, he said.

Home tests also can be useful during cold and flu season to determine if someone with cold or flu symptoms actually has COVID-19.

“Home testing is a great way to keep the virus from spreading within your home if someone is sick or was potentially exposed,” said Daniel Larremore, assistant professor in the department of computer science and the BioFrontiers Institute at the University of Colorado Boulder.

Mina said he hopes more people consider the combined benefit of vaccination and home testing to keep people safer and get back to their routines while the virus is still out there. “The reemergence of other respiratory viruses, like RSV and influenza, will surely create challenges again this fall and winter,” he said. “If we want to return to normalcy and protect ourselves, accessible and accurate home testing should be one tool that we use and rely on to keep ourselves and loved ones safe.”This article originally appeared in The New York Times.