Westchester County's Guide to COVID-19 Test Types

The public has many questions about the different types of COVID-19 testing.

The Westchester County Department of Health has posted a thorough and informative overview prepared by the U.S. Food and Drug Administration. The document can be found at https://health.westchestergov.com/images/stories/PDF/covidtestingbasicsJuly2020.pdf

There are two different types of tests – diagnostic tests and antibody tests.

A diagnostic test can show if you have an active coronavirus infection and should take steps to quarantine or isolate yourself from others. Currently there are two types of diagnostic tests which detect the virus – molecular tests that detect the virus’s genetic material, and antigen tests that detect specific proteins on the surface of the virus.

An antibody test looks for antibodies that are made by your immune system in response to a threat, such as a specific virus. Antibodies can help fight infections. Antibodies can take several days or weeks to develop after you have an infection and may stay in your blood for several weeks or more after recovery. Because of this, antibody tests should not be used to diagnose an active coronavirus infection. At this time researchers do not know if the presence of antibodies means that you are immune to the coronavirus in the future.

In the FDA document, you'll find information about the effectiveness of each of these kinds of tests, as well as information about the ways these tests are conducted, how long results may take, and what each of these tests can and cannot tell you.

I hope this guide will be helpful in answering your questions.

For additional information about COVID-19 testing, resources and safety guidelines, please visit the Department of Health's COVID-19 page at https://health.westchestergov.com/2019-novel-coronavirus