How Accurate are the Lab Results for COVID-19 Tests?

COVID-19 has altered just about everything in our society. We now exist in a world where we not only rely on COVID-19 testing, we realize that it can mean the difference for some between life and death. Even though they were never setup to process millions of tests at a time, the laboratories tasked with processing the massive quantities of virus tests have stepped up to the plate to bring everyone results as quickly and efficiently as possible. Due to the overwhelming number of COVID-19 tests, a logical question to ask is “how accurate are the lab results?”

There are around 94 public health laboratories around the U.S. that are involved in COVID-19 testing, not including some of the private laboratories. The FDA (Federal Drug Administration) has indicated that for those private labs that have already received certification for the performance of complex testing, they won’t stop them from performing COVID-19 tests.

The Samples

Before answering a question of accuracy there is a need to recognize that samples are quite often imperfect. These can be situations where the sample was done incorrectly so that not enough specimen was collected or even when a patient is in an early stage of infection or is recovering so that the sample doesn’t have sufficient viral material for a lab to deem it as positive.

Other conditions that can affect a sample can include storage and transport. If stored and/or transported in improper conditions or not in a timely condition, a sample can be considered as no longer viable.

There are currently two types of tests used to diagnose the COVID-19 virus: a molecular test that looks for the specific COVID-19 virus genetic material and the antigen test that is looking for the proteins that are made by the virus. Samples are typically taken using a long swab that is placed in the deeper areas of the nasal passage.

The antibody test for COVID-19 is used after someone has had a full COVID-19 recovery and detects specific COVID-19 antibodies that are present in blood and other specific body fluids. This is not a test for diagnosis.

It’s All About the Test Itself

Not all tests are created equal. COVID-19 and other test types are based on two variables: “sensitivity,” which is the test’s ability to see if a patient has been infected, and “specificity” which is the ability of the test to see if the patient isn’t infected. A quality test that has good sensitivity will have a lower likelihood of a result that is false-negative. A test that has good specificity has a lower likelihood of a result that is a false-positive.

All of the COVID-19 tests are designed to find results that are COVID-19 related only. There is no confusion between any other viruses, vaccinations, or even flu shots.

Consumers need to rest-assured that the companies producing the COVID-19 tests are required to comply with strict guidelines and proof so that they can be EUA (Emergency Use Authorization) referred.

At the Labs

The duration of time taken for COVID-19 tests depend on the size of the laboratory, the number of machines that they have, and the number of people on board to process the tests. For genetic processing, lab workers are required to send the sample through a cleaning process and extract the RNA (ribonucleic acid) from the virus. This is the molecule that assists in gene regulation. These processes are more time consuming. Larger labs have automated systems that can speed up these two steps.

Once the extraction of the RNA is accomplished, lab technicians must mix the sample with special chemicals and then run it through a machine for analysis in a process called PCR (polymerase chain reaction). This process will detect whether the sample submitted is COVID-19 negative or positive. The PCR process averages around 6 hours from start to completion.

Some of the larger commercial labs can accomplish around 20,000 tests per day and hope to increase that amount. Smaller labs do far fewer, but even they have been increasing in volume. The FDA has given approval to various labs or manufacturers under the EUA (Emergency Use Authorization) rules for around a dozen testing kits used in PCR machines to speed up the process.

As noted, the results of a COVID-19 test is based on the arrival of a perfect specimen that has been stored and transported in a timely manner. Given all of the hurdles that laboratories have had to overcome combined with the challenges of high demand and expediency, it is astounding that the results they bring can generally be trusted. While there are false-negative and false-positive situations, these seem to be in conditions that had other variables that affected the samples. Overall, research is showing that the laboratories that we turn to for the results of COVID-19 testing have succeeded in accomplishing their goals.