COVID tests

Disclaimer: I have no medical background, experience, or credentials. I am just a random layperson. Nothing on this page is medical advice.

When should I get tested?

5-7 days after suspected exposure 1

What diagnostic tests are available?

There are two main kinds: RT-PCR and rapid antigen. This table summarizes my understanding of some aspects of these tests and their availability/accessibility in NYC.

  RT-PCR tests Rapid antigen tests
Availability Widely available; You can go to many official city locations, several hospital systems offer them, and many doctors offices. Harder to get; it’s available at a few sites in the city testing program, a few urgent cares that will submit to insurance, and more locations that will test you but charge cash upfront.
Cost Free at NY Health + Hospitals; elsewhere, it’s usually covered by insurance. (Still— check with your insurer in advance!) A handful of places will take insurance (again, check with your insurer ahead of time); most won’t accept insurance and instead charge the patient ~$200 up front.
Accuracy Highly accurate Slightly less accurate than PCR
Time to get results 10 hours to 2 weeks (usually ~2 days) 20 minutes to 1 day (usually ~30min)

Interpreting COVID tests

If you get a positive RT-PCR, you almost definitely have COVID.2

If you get a negative test, that does not mean that you are COVID-free. To expand on that..

  • If you are exposed to COVID and you acquire it, it takes days after the exposure for tests to be able to detect it. Even after people develop symptoms, the false-negative rate may still be fairly high, depending on the specific test used. (PCR is a technique, so there are different brands and sub-types of test that use PCR.) The false-negative rate varies by the specific test assay that’s used. 1
  • If you get a negative test, do not assume that you don’t have it. You might:
    • Not have it, or
    • You have it and it’s still incubating, or
    • You have it and the test just failed to identify it. 1

Useful articles from authoritative sources

  1. When should I be tested?, MIT Medical.  2 3

  2. “Generally speaking, if a test result comes back positive, it is almost certain that the person is infected.” If you’ve been exposed to the coronavirus, by Harvard Health Publishing (associated with Harvard Medical School).