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Last updated: Jan 24, 2022
7 min read

When should I take a COVID test?

If you’ve been exposed to COVID, you should take a COVID antigen or PCR test 5–7 days later. The first day after you were exposed is day one. You can get tested at a testing site or self-test at home. You should also take a test if you develop symptoms, even if it’s before or after 5–7 days.

Important

Information about the novel coronavirus (the virus that causes COVID-19) is constantly evolving. We will refresh our novel coronavirus content periodically based on newly published peer-reviewed findings to which we have access. For the most reliable and up-to-date information, please visit the CDC website or the WHO’s advice for the public.

Maybe you’ve been exposed to someone who tested positive for COVID, or you’re starting to feel a tickle in your throat and wondering if you’ve caught it. But figuring out which day to take the test to get the most accurate results can be tricky. We spoke to our resident Infectious Disease specialist, Dr. Gina Allegretti, to learn more about when you should take a COVID test after exposure to someone who tested positive or after symptoms appear.

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I was exposed to someone who tested positive. When should I get tested?

“First,” says Dr. Allegretti, “make sure you were really exposed. Saying hi to a masked neighbor outside for a minute while you’re also masked likely won’t result in infection and isn’t a reason to get tested.” She says you should follow the CDC’s guidelines. “Being exposed means you were in close contact (within 6 feet of someone who tested positive) for 15 minutes or more.” If you were exposed, you should wait until five days after exposure before getting tested (CDC-a, 2022). 

The counting can be a little confusing, though. “The day that you’re actually exposed is considered day zero,” explains Allegretti. “For example, if you visited someone on Sunday and found out afterward that they were positive for COVID, Sunday becomes day zero. You should take a test five days later, on Friday.  

Five days might seem like a long time to wait, but there’s a reason you shouldn’t test right away. “Getting tested within the first few days of exposure likely won’t tell you what you need to know, since a day or two isn’t enough time for the virus to replicate enough to be detected by a COVID test,” says Allegretti.    

There is an exception to the testing rule. If you’ve had a confirmed case of COVID in the past three months and you don’t have any symptoms, but you’ve been exposed to someone who tested positive, you don’t need to get tested again because it’s much less likely that you will be infected (CDC-a, 2022).

What if I have symptoms? When should I test?

If you have symptoms of COVID, though, with or without a known exposure, the picture’s a little different. “You don’t have to wait until day 5 because when you have symptoms, the amount of virus in your body (the viral load) may already be high enough to detect,” Allegretti says.

 Symptoms of COVID-19 include: 

  • Fever and chills
  • Runny nose or congestion
  • Cough
  • Body aches
  • Headaches
  • Sore throat
  • Loss of sense of smell and taste 

But no test is foolproof, even when you have symptoms. You can still get a false negative test result. That’s why healthcare providers take the whole picture into account when they evaluate a person’s results. 

“If you live in a house with four other people who are all positive for COVID and you start experiencing symptoms yourself without a positive test,” says Dr. Allegretti, “it’s more likely that your result is inaccurate, and it may be a good idea to test again in a few days and stay away from other people until you get your results.” 

If you’re not sure whether or not you need to take a test, the CDC (Centers for Disease Control and Prevention) has an interactive online tool called the Coronavirus Self-Checker. It will ask you a few questions to help you decide if you should take a test, when you should test, and what test results mean. When in doubt, it’s always a good idea to check with your healthcare provider, who can provide even more information.  

What type of test should you get?

Once you decide to get tested, picking the right test may seem tricky. We’ve broken it down for you. There are two main types of COVID tests:

  • Diagnostic tests, like antigen tests and PCR tests, can each be used to determine if you have COVID now. 
  • Antibody tests: These test your immune system’s response to the virus or vaccine and won’t help determine if you’re currently infected with the virus, but they can tell you if you’ve likely been infected (or received a vaccine) in the past. Antibodies usually can’t be detected until at least two weeks after an infection or vaccination

Antigen tests are considered to be rapid tests because they give you a result quickly—usually within 10–15 minutes—and don’t require special machinery (CDC-b, 2022). While there are some rapid PCR tests, most PCR tests take hours to days to give you results, so they may not be the best option if you need an answer right away.  

“The advantage of PCR tests is that they are a bit more sensitive, meaning they’re a little bit better at identifying the virus if you’re infected,” says Allegretti. “But they aren’t as readily available as antigen tests.”

Where can you get a test?

Rapid tests are available from a healthcare provider’s office, urgent care center, or emergency department. Some regions have mobile testing sites, but this varies by location. It’s a good idea to call before going to get a test since you may need to schedule an appointment. 

If you don’t have a testing center nearby, you can use an at-home COVID test kit to do your own self-test without ever leaving your home. You can order a home test kit online or find them in large chain pharmacies like Walgreens and CVS. They’re a convenient option if you can’t get out, and many of them are even covered by health insurance. You can also log in to order free rapid tests straight to your house from https://www.covidtests.gov/

The FDA’s (Food and Drug Administration) data suggest that rapid antigen tests might not be as good at detecting certain strains of the coronavirus, like Omicron (FDA-c, 2021). If you have symptoms of COVID-19 and your antigen test is negative, it’s a good idea to talk to a healthcare provider to determine whether it’s a good idea to get another test. 

What should I do while I wait for my results? 

The answer to this question depends on your symptoms and vaccination status. For example, what if you’re exposed to COVID but have no symptoms? If you’re fully vaccinated, you don’t need to isolate at home, but you should still wear a mask around others for ten days and get tested on day 5. If you’re unvaccinated, you should isolate at home for at least five days, wear a mask around others for ten days, and get tested on day 5 (CDC-d, 2022).

It’s important to wear a mask even without symptoms because you can spread the virus to others before you know you’re infected. The virus is most contagious for a day or two before you start to have symptoms and two or three days after (CDC-c, 2021). “The best types of masks,” says Allegretti, “are N95s. They have a close-fitting seal around your face and small pores to keep respiratory droplets from crossing through them.”

If you’re exposed to COVID, and you have symptoms, you should isolate at home and wear a mask whenever you’re around others. This recommendation applies whether you’ve had the COVID vaccine or not. Don’t forget to get tested when you develop symptoms (CDC-d, 2022).

What should I do if my test is positive? 

If you tested positive on an antigen test or PCR, it means you have the virus in your body right now. The CDC recommends that you isolate at home to prevent spreading the virus to others. You should wear a mask around others in your household. If you don’t develop symptoms, you may stop isolating at home after five days, but you should continue to wear a mask for 10 full days (CDC-d, 2022). 

If you develop symptoms, you should isolate at home for at least five days. After five days, you can stop isolating if your symptoms are getting better and you don’t have a fever (CDC-d, 2022). You should continue to wear a mask for at least ten days. If you aren’t sure how long you should stay home or wear a mask, it’s a good idea to speak to a healthcare professional. 

“Keep in mind that a PCR test can remain positive for months after the infection is no longer contagious, so you can’t test out of isolation,” reminds Dr. Allegretti. 

What should I do if my test is negative? 

If your test is negative on day five and you don’t have any symptoms, it may be good news. But remember that a negative rapid test isn’t always accurate in the first few days or with some variants. You should continue to wear a mask until day 10 and monitor yourself for symptoms. 

References

  1. Centers for Disease Control and Prevention (CDC-a). (2022). Test for Current Infection. Retrieved on Jan. 12, 2022 from https://www.cdc.gov/coronavirus/2019-ncov/testing/diagnostic-testing.html
  2. Centers for Disease Control and Prevention (CDC-b). (2021). COVID-19 Testing: What You Need to Know. Retrieved on Jan. 12, 2022 from https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html
  3. Centers for Disease Control and Prevention (CDC-c). (2021). CDC Updates and Shortens Recommended Isolation and Quarantine Period for General Population. Retrieved on Jan. 12, 2022 from https://www.cdc.gov/media/releases/2021/s1227-isolation-quarantine-guidance.html
  4. Centers for Disease Control and Prevention (CDC-d). (2022). Quarantine and Isolation. Retrieved on Jan. 12, 2022 from https://www.cdc.gov/coronavirus/2019-ncov/your-health/quarantine-isolation.html
  5. Centers for Disease Control and Prevention (CDC-e). (2021). Coronavirus Self-Checker. Retrieved on Jan. 12, 2022 from https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/coronavirus-self-checker.html
  6. Centers for Disease Control and Prevention (CDC-f). (2021). Need a COVID-19 test? Retrieved on Jan. 12, 2022 from https://www.cdc.gov/coronavirus/2019-ncov/images/symptoms-testing/COVID-Testing-Flowchart_v2_Updated.jpg
  7. U.S. Food and Drug Administration (FDA-a). (2021). Coronavirus Disease 2019 Testing Basics. Retrieved on Jan. 12, 2022 from https://www.fda.gov/consumers/consumer-updates/coronavirus-disease-2019-testing-basics
  8. U.S. Food and Drug Administration (FDA-b). (2021). FAQs on Testing for SARS-CoV-2. Retrieved on Jan. 12, 2022 from https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/faqs-testing-sars-cov-2
  9. U.S. Food and Drug Administration (FDA-c). (2021). SARS-CoV-2 Viral Mutations: Impact on COVID-19 Tests. Retrieved on Jan. 12, 2022 from https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/sars-cov-2-viral-mutations-impact-covid-19-tests