COVID-19 Testing, At-Home Tests, and What to Know about Isolation and Quarantine

Swab going into a nose

A nose swab PCR test is one of the most accurate ways to detect COVID-19.

The best way to protect yourself from COVID-19 is to get vaccinated and boosted. After you are vaccinated and boosted, you should still wear a mask while in close contact with others, avoid crowded indoor settings, wash your hands often, and be alert for symptoms.

Mini Kamboj

Mini Kamboj

Many of our patients have weakened immune systems because of cancer and its treatment, and they are particularly vulnerable to severe COVID-19. At Memorial Sloan Kettering Cancer Center, we update our COVID-19-related recommendations and policies as often as needed to keep our community safe. This means that sometimes the practices at our locations are stricter than the general guidelines from the Centers for Disease Control and Prevention (CDC).

Mini Kamboj, Memorial Sloan Kettering Cancer Center’s Chief Medical Epidemiologist, explains what our patients and their families need to know about COVID-19 testing, quarantining after exposure, and more.

I was exposed to someone with COVID-19. What should I do?

The CDC has information on their website about what to do if you were exposed to someone with COVID-19. Generally, you should minimize contact with other people as much as possible, and you should wear a high quality mask. Test yourself 3 to 5 days after the exposure. If you test negative, you should continue to stay masked for another 5 days, for a total of 10 days after the exposure). More information from the CDC »

    What do I do if I test positive for COVID-19? If I test positive for COVID-19, should I get a repeat test at the end of isolation to ensure that I am negative? How long could I test positive for?

    If you test positive for COVID-19, you should isolate yourself at home. This means that you should separate from others, stay in a specific “isolation room” or area, and use a separate bathroom if possible. Don’t share personal household items like cups, towels, and utensils.

    Even though the risk of spreading infection is highest in the first 5 days after symptoms appear, patients receiving certain cancer treatments can be contagious for a more extended period and are also more vulnerable to catching an infection from others. That’s why MSK recommends that patients, their close family members, and friends isolate themselves for 10 days — regardless of symptoms — after any positive COVID-19 test.

    When can I get tested at MSK?

    If you are a patient with COVID-19 symptoms and are receiving your cancer care at MSK, you can get tested at any of our testing locations. You can also get tested at an outside location. If you are required to have testing as part of a safety protocol we have implemented — for example, before surgery — you must get tested at MSK.

    To get a COVID-19 test at MSK, you must call your doctor’s office to schedule. We do not offer walk-in COVID testing at our clinics.

    When and where can I get tested outside MSK?

    If you do not have symptoms or any upcoming procedures, you are not able to get tested at MSK. You can find a local testing location using the following links:

    What’s the most accurate test for COVID-19?

    PCR tests are the most accurate tests for COVID-19. These tests are processed in a laboratory and they usually take at least one day (and could take several days) to provide a result. PCR tests look for genetic material from the virus and can reproduce many copies of viral-related DNA from even the smallest sample.

    What’s the fastest test for COVID-19?

    Antigen tests are sometimes referred to as “rapid tests” or “at-home tests.” They can be processed almost anywhere, including in a doctor’s office, pharmacy, or even at home. They search for pieces of protein from the COVID-19 virus and can provide results in 10 to 15 minutes.

    Antigen tests tend to be fairly accurate for people with symptoms but may not be as reliable if you have no symptoms. If you have symptoms and test positive with an antigen test, you most likely have COVID-19. You should isolate yourself and seek medical care as necessary. If you have symptoms and test negative, you should seek out a PCR test.

    There are several FDA-authorized COVID-19 antigen tests that you can do at home and are available for purchase online or in a store. Visit the FDA’s website for a list of authorized self-tests. While antigen tests are very fast, they are less accurate than PCR tests.


    August 15, 2022


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