I remember the time (about one year ago) when I could only provide one COVID test for patients walking into urgent care: the PCR or polymerase chain reaction.
Back then, patients had no choice other than to get a nasal swab that was uncomfortable, irritating, and tended to bring them to tears. Now, there are many different types of COVID tests available, but you should be well-informed about what each test is and how it can help you navigate life decisions. In the busy urgent care offices where I work throughout the five boroughs of New York City, we offer three COVID tests: the rapid COVID test, the PCR, and the antibody test.
The first test is the rapid COVID test. This is a swab that goes in your nose. It became widely available during the last few months of 2020. The rapid is an antigen test that works by detecting a specific protein on the virus’s outer coat. This test can be run at the office where you are seen and provides results in less than 30 minutes.
The obvious benefit is that you can quickly secure an answer to, “Do I have the virus?” or “Am I OK to be around others?” A crucial thing for patients to realize is that if you are low-risk (meaning you are not sick and have had no known COVID exposures), the rapid test is reliable and an excellent option. Generally speaking, the rapid is acceptable for domestic travel, non-health care workplaces, and for many educational institutions.
The “gold-standard” COVID test remains the PCR. This is a swab that can either go in your nose or throat. This test works by amplifying pieces of the virus’s genetic material so that it can be more easily detected. Many urgent care offices do not process these tests on-site, so they are sent to another location (a lab) for analysis.
You will typically get your results back in one to five days, but there are facilities that are able to give you results the same day. Many patients have heard that the PCR is a “better” test (compared to the rapid) because “it is more accurate.” As a general rule, the PCR is more reliable under certain conditions. For example, if there is a mismatch between your rapid test result and reality, a PCR would be done for confirmation.
So to make things clear, consider these two real-life situations: you are actively sick with COVID-like symptoms but have a negative rapid test, or you have no symptoms and feel fine but have a positive rapid test. In both cases, the PCR would be done to check for a false negative and false positive, respectively. There is no test currently available that would be used to confirm the results of the PCR. The PCR is also acceptable for most international travel and tends to be the preferred examination for surgical procedures and for those who work in health care settings.
In short, what I would recommend is that if you are asymptomatic, a rapid test is a great choice. If you are symptomatic, then it is reasonable just to stick with the PCR.
The final test is the antibody test. This is a blood test that normally produces results in 24-48 hours. The important thing to know about an antibody test is that it does not tell you if you have an active COVID infection. It may tell you if you had COVID in the past, but it is not helpful to find out if you have an infection now. And it’s important to keep in mind that a positive test (you have antibodies) doesn’t necessarily mean you had COVID. The presence of antibodies also does not imply immunity. On the other hand, a negative test (you do not have antibodies) doesn’t necessarily mean you did not have COVID.
Even more, what we have learned in the past year is that after a COVID infection, your natural antibodies tend to wane after 90 days. This simply means that if it has been more than three months since you tested positive, interpreting your antibody test result becomes fuzzy.
Finally, patients need to understand that whether or not you have antibodies plays no role in determining your eligibility for a COVID vaccine.
I hope this information helps you to determine which COVID test is right for you. And as always, it is wise to have a conversation with your medical provider.
Elijah Sadaphal is an emergency physician.
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