In Part One of this blog, focused on helping employers understand the multi-faceted strategies needed to reopen workplaces following the pandemic, I mentioned that there are two main types of COVID-19 tests available: diagnostic (tests for current infectivity) and antibody (tests to determine previous infection). As HireRight’s Chief Medical Officer, I receive a lot of questions from employers about testing, including what are the currently available types of COVID-19 tests. In the second part of this blog series, I will now take a closer look at the various options currently available in the market for these types of tests.
Understanding the Different Types of Tests Available
1. Antigen Test (which in many instances is a point of care diagnostic test)
The FDA has granted emergency use authorization (EUA) for antigen tests that can identify current infectivity. An antigen test detects the presence of a specific viral antigen (molecular structure on the surface of the virus that are recognized by the immune system). The lab uses specially tagged antibodies (with dye or a tracer) that attach themselves directly to the viral antigens. The tagged antibodies can then be seen either with specialized instrumentation or the human eye (depending upon the test).
Antigen tests can be done without the need of specialized laboratory equipment and are packaged in self-contained testing devices that can be read in minutes. Antigen tests perform best in the early stages of infection when viral antigens are generally the highest.
- Specimen sample: Nasal or throat swab
- Pros: Rapid turnaround and very low cost when compared to molecular tests
- Cons: Result accuracy is not as high as molecular testing and is variable across testing platforms. Depending on the situation, a doctor may recommend a Polymerase Chain Reaction (PCR) test to confirm a negative or positive antigen test result.
- Best Use Case: Person has a known exposure to a confirmed case of COVID-19. Also useful for screening large numbers of people, especially in high-risk settings in which repeat testing is used to inform and control transmission spread.
2. Antibody Test (also known as serologic testing)
Antibody testing checks for blood borne immunoglobulins (IgM and IgG). Once a person is exposed to the virus, the body produces IgM antibodies first then IgG antibodies as part of the immune response system. Antibodies help fight off infections. It can take up to two weeks after exposure to start developing these antibodies at detectable levels; therefore, it is not the best test to use for detecting current infectivity. Some people may take longer than the two weeks to develop antibodies and some may never develop antibodies at all.
A positive result can be misleading, it can mean you have developed antibodies from a COVID-19 virus or it could mean that you have developed antibodies from a virus from the same family of viruses (called coronaviruses). At present, the Center for Disease Control (CDC) does not know if the presence of antibodies means a person is immune to the COVID-19 virus or how long that protection may last. The EEOC prohibits employers from requiring antibody testing before allowing employees to re-enter the workplace as potentially discriminatory under the ADA.
- Specimen Sample: Finger prick or blood draw
- Pros: Widespread testing could help researchers understand how many people have been infected/exposed.
- Cons: There are several different antibody tests available, some perform better than others. People tend to think that having antibodies provides immunity from catching it again – no current evidence supports this theory.
- Best Use Case: Really reserved for medical/research purposes at this time with no role in employment testing
3. Nucleic Acid Detection Testing (also known as PCR and molecular testing)
This type of test looks for the viral genetic materials of a specific virus in specimen samples. Generally, these tests are highly accurate; however, it takes a few days before the virus starts replicating in the nose and throat, so the test won’t identify someone who has recently been infected. Currently, this type of testing is considered the “gold standard” for clinical diagnostic detection of COVID-19 and is the most accurate and widely used tests currently in the market. Results may be available in minutes if analyzed onsite with specialized instrumentation or a few days or longer if sent to an outside lab.
This test is synonymous with molecular and Polymerase Chain Reaction (PCR) testing. A laboratory is required for this type of testing, but some molecular point-of-care tests are becoming available and the testing process continues to improve and is becoming highly automated.
- Specimen Sample: Nasal swab or saliva (for COVID-19)
- Pros: The testing provides a high degree of accuracy, and when compared to viral cultures, this test is faster and less expensive
- Cons: The testing is still somewhat expensive. Laboratory throughput remains an issue, and the majority of the specimen collections still need to be overseen by a medical professional.
- Best Use Case: Assurance or ad hoc testing for employment purposes
4. Cell Culture Testing
If molecular testing is the gold standard then cell culture testing is the platinum level. This is a traditional laboratory technique that grows the various viruses in different mediums (cell lines). At present, due to cost and time, cell cultures are not being used at all for any form of employment testing.
What is the status of instant tests?
The ideal test for COVID-19 would be a direct-to-consumer diagnostic test that would not require a medical professional to interpret the result. At this point in time, that test does not exist (however, companies are working on it).
Currently, there are several COVID-19 tests that provide “instant” results; however, these tests require a variety of requirements that make them very hard for the typical employer to deploy. These requirements include medical oversight of the collection, specialized instrumentation, and some level of laboratory accreditation. As time rolls forward, many or all of these requirements will fall off, but as of today, these roadblocks remain.
Questions Employers Should Consider
As an employer, if you elect to do COVID-19 testing as part of your return-to-work policy, here are some items that you need to consider:
- When will I test employees?
- What type of test will I use?
- Do I want medical oversight of the collection process?
- What kind of laboratory throughput do I need?
- How do I want to view the employee test results?
- What mechanisms are available to help ensure I do not violate my employees’ rights?
All of these are complex questions to answer but should be discussed with your testing service providers. HireRight is available to help you with your COVID-19 screening needs. Click here for additional information on our testing solution or visit: https://www.hireright.com/services/drug-health-screening/COVID-19-Screening