How Does Quest Diagnostics Test For The Coronavirus?

How Does Quest Diagnostics Test For The Coronavirus?

Introduction: Quest Diagnostics Test

Quest Diagnostics is one of the largest American clinical laboratory testing companies. It is a Fortune 500 company that operates in the US, UK, Mexico, and Brazil. Quest has collaborations with hospitals and healthcare units across the globe. It offers a broad range of services used in diagnosing, monitoring, and treating medical conditions.

The company sells diagnostic testing kits for cancer, neurological disorders, infectious disease, cardiovascular disease, and drug testing. In late April, Quest Inc introduced the first consumer-ordered COVID-19 antibody test. Customers can order a test online and take it at the nearest lab. A doctor’s referral is not required. Results are given in one or two days.

Quest Diagnostics Test: How Is This Test Different From The One Prescribed By The Doctor?

There are two main types of COVID-19 testing available. If a patient goes to a doctor and the doctor suspects coronavirus infection, he is prescribed a COVID-19 Molecular Swab Test. A sample is collected from the back of the nose, near the throat. This test detects for the presence of the virus itself.

New visualisation of the Covid-19 virus
Photographer: Fusion Medical Animation | Source: Unsplash

Another type of test available is the serology test. It relies on a blood draw. When an alien substance enters the human body, our immune system can identify it as a foreign object. This foreign object is called an antigen. To fight the antigen, our immune system produces antibodies. Anyone who had contracted coronavirus in the past should have these antibodies in their system. These antibodies can be present in the bloodstream for years after the infection.


The Quest Diagnostic Test for coronavirus detects the presence of immunoglobulin G (IgG) antibodies in the bloodstream. The antibodies generally become detectable after 10-14 days of the infection.

Materials at a laboratory bench at the National Institutes of Health Clinical Center.
Photographer: National Cancer Institute | Source: Unsplash

So, this test cannot be used to diagnose current infections. It can only be used to see whether the person has a history of the infection. This information can be used to determine the percentage of a population that have contracted the disease and are therefore presumably immune. Some people are claiming that antibody tests will be useful in identifying who is immune enough to start working and who is not. However, caution needs to be exercised as we do not have enough information on how much protection antibodies can provide or for how long.