Coronavirus Testing Methods
What you need to know!
You’ve probably heard a lot about coronavirus testing recently. The FDA, WHO, ICMR & Union Health Ministry has been working around the clock to increase the availability of critical medical products, including tests for the coronavirus, to fight the COVID-19 pandemic.
Here's a look at various testing methods available.
There are two types of tests- Diagnostic tests and Antibody tests
1. Diagnostic Test
A diagnostic test can show if you have an active coronavirus infection. Currently there are two types of diagnostic tests – Molecular (RT-PCR) tests that detect the virus’s genetic material, and Antigen tests that detect specific proteins on the surface of the virus.
1.1 Molecular Testing (RT-PCR)
Tests used for diagnostic purposes; use reverse transcriptase to create and amplify DNA from SARS-CoV-2 RNA. The molecular test is much more specific but false negatives do occur. While these tests can detect viral RNA/DNA, they do not distinguish between replicating virus (infectious) and remnants of viral RNA/DNA.
1.2 Antigen Testing
Antigen tests usually provide results diagnosing an active coronavirus infection faster than molecular tests, but antigen tests have a higher chance of missing an active infection.
If an antigen test shows a negative result indicating that you do not have an active coronavirus infection, molecular test is used to confirm the result.
Currently, there is only one antigen test given EUA by the FDA. This test detects viral proteins in the nasal cavity. While the antigen test can be completed in minutes, it is not as sensitive as the PCR tests and may not detect all active infections (false negative).
2. Serological (Antibody) Testing
An antibody test looks for antibodies that are made by the 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 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.
There are some new diagnostic tests available with alternative methods and benefits.
1. Rapid, point-of-care diagnostic tests use a mucus sample from the nose or throat but can be analyzed at the doctor’s office or clinic where the sample is collected and results may be available in minutes. These may be molecular or antigen tests.
2. At-home collection tests are prescribed by a doctor but allow the patient to collect the sample at home and send it directly to the lab for analysis. Only one molecular test has received EUA from the FDA.
3. Saliva tests allow a patient to spit into a tube rather than get their nose or throat swabbed. Saliva tests may be more comfortable for some patients and may be safer for health care workers who can be farther away during the sample collection.
1. U.S. Food and Drug Administration