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
- The FDA has a page discussing the different types of COVID test.
- Here’s another discussion of the types of COVID tests on the Harvard Health Blog.
- When should I be tested? from MIT Medical
- CDC’s COVID testing page
When should I be tested?, MIT Medical. ↩ ↩2 ↩3
“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). ↩