Last Updated August 17, 2020

1. What is molecular PCR testing and when is it used?

Molecular testing is the gold standard of diagnostic testing for COVID-19. This highly accurate testing method uses “PCR” (polymerase chain reaction) to detect the presence of a virus. For COVID-19 testing, this method typically uses upper and lower respiratory specimens.

Molecular testing was the first kind of testing for COVID-19 available in the United States. A dozen ACLA member laboratories currently perform molecular testing for COVID-19. Since February 29, when FDA guidance first allowed high-complexity laboratories, including academic, hospital and commercial labs, to step forward with novel tests for COVID-19, ACLA members have performed millions of these diagnostic tests. For the latest number of tests performed, including daily totals, click here.  

2. What is antibody testing and when is it used? 

Serologic testing, also referred to as antibody testing, is used to analyze blood specimens for the presence of proteins, called antibodies, made in response to an infection. The presence of specific antibodies indicates that an individual has been infected by that specific pathogen. When used appropriately, high-quality serologic testing may help determine the number of individuals who have been infected with SARS-CoV-2 and inform public health strategies. 

3. If someone has been exposed to COVID-19 and believe they may be immune, will the antibody test reliably confirm this?

The presence of antibodies in a patient’s blood demonstrates an immune response to infection – no one is debating that point. What we don’t know yet is the level or the duration of immunity against reinfection that these antibodies provide. The science and research continues to progress each day, and clinical laboratories are working closely with researchers and public health experts to piece together the complete picture of this evolving virus.

The value of antibody tests for COVID-19 is significant. High-quality serologic testing can help determine the number of individuals who have been infected with SARS-CoV-2 and inform broader public health strategies.

Antibody testing also has a vital role in supporting ongoing development of vital COVID-19 treatments and vaccines, and preliminary reports indicate that convalescent plasma transfusions from patients who have tested positive for these antibodies are providing relief to some of the sickest patients.

4. What is antigen testing and when is it used?

Patients may be most familiar with antigen testing as an initial diagnostic tool used at a hospital or doctor’s office to deliver rapid results for flu or strep throat. This test typically is performed at the point-of-care.

Antigen testing for COVID-19 can be used to quickly detect fragments of proteins found on or within the virus by testing samples collected from the nasal cavity. While antigen tests deliver rapid results, these tests are not as sensitive as molecular PCR tests, and as a result, the FDA has cautioned that “negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment decisions or to prevent the possible spread of the virus due to a false negative.”

5. What does point-of-care testing mean? 

Rapid or point-of-care testing refers to testing that is done at or near where patients receive care, such as physician offices and ambulatory care centers. Point-of-care testing plays a vital role in our nation’s response to the pandemic, but this type of testing does have limitations. In general, point-of-care testing is less accurate than molecular PCR testing performed in laboratories. Another difference between point-of-care platforms and instruments that ACLA members typically use is volume; laboratory-based testing utilizes high-throughput platforms that process several thousand specimens a day.

6. What kinds of tests are available in a provider’s office or testing site? Are there at-home specimen collection options available?

Molecular PCR tests are both the most accurate and the most widely available diagnostic tests for COVID-19 in the United States. In physician offices, hospital settings and drive through sites, patient specimens are collected and sent to a laboratory where highly accurate results are typically reported within a few days. Rapid point-of-care tests also can be available in many of these settings. In addition, the FDA has authorized several at-home specimen collection kits for laboratory-based molecular tests. This method allows patients to collect their own nasal specimens, which then are sent to a laboratory for testing. At-home specimen collection is not currently available in all states due to local restrictions.

Currently, the FDA has not approved at-home specimen collection for serologic (antibody) testing or for antigen testing. Antibody testing, which requires a blood sample, is offered through many patient service centers, physician offices and other health care settings.  The first antigen test was recently approved by the FDA.  In addition, ACLA members are also working on innovative approaches to assist employers with return to work strategies, including on site specimen collection support.

7. Why does testing access vary by state?

Guidelines communicated to clinicians about who should be tested vary state to state. ACLA members are working closely with governors to deliver accurate, highly scalable testing through our 24/7 national network. ACLA members do not reserve testing capacity by state or region, but direct available capacity based on need so we can remain flexible to respond to outbreaks and hotspots. 

8. Do Medicare and Medicaid cover COVID-19 testing?

Yes. Medicare Part B covers molecular and serologic COVID-19 tests with no cost sharing for beneficiaries. Medicaid programs are required to cover COVID-19 testing for beneficiaries, though some state programs have taken concerning actions to restrict coverage for certain tests.    

9. How are patients prioritized for testing?

Guidelines communicated to clinicians about who should be tested is determined at the state-level and therefore varies state-to-state. The CDC recommends that clinicians use their judgment to determine whether a patient should be tested for COVID-19. The agency has also released guidelines to help inform these decisions and prioritize testing for patients who need it most.

10. What are labs doing to minimize disruption to non-COVID testing?

ACLA members are committed to providing patients with the essential tools they rely on to identify, manage and treat a range of health conditions. Laboratories are making adjustments to maintain predictable access to laboratory services for patients, and many ACLA member laboratories with patient service centers are designating special hours for routine testing for high-risk populations, such as seniors and those living with chronic health conditions.  

11. What is test pooling and how does it work?

Pooled testing allows a laboratory to combine samples from multiple patients together and test them as a pool rather than individually to detect the SARS-CoV-2 virus. If the result of the pooled test is negative, all individual samples in the pool are reported as negative. If the result of the pooled test is positive, one or more samples in the pool may be positive. A laboratory then seeks to identify which specimen(s) contains the virus.

Pooling allows for more specimens to be tested at once, maximizing capacity and reducing the use of some supplies (e.g., reagents) that are in short supply. Pooled molecular diagnostic COVID-19 testing can be used efficiently in areas and populations of low prevalence where most results are expected to be negative. However, pooling is not an appropriate methodology to use in communities or populations with high rates of infection. If a high number of specimens are positive, a lab has to run more tests to determine which sample(s) contain the virus, consuming more reagents and other supplies that are already scarce.

Additionally, pooled testing requires changes in laboratory workflow and extra steps, many of them manual steps that disrupt standard operations for non-pooled testing. In pooling, extraction of the specimens to be tested involves the creation of a separate pooled assay from a number of different patient samples. The samples selected for pooling must be retained for further analysis, if needed. Moreover, because pooling can be used only in populations with low disease prevalence, a lab must sort specimens by site of collection or zip code to determine if pooling is feasible. Creating the pools and retesting individual samples if a pooled test is positive and the individual positive sample(s) cannot otherwise be identified requires added manual labor.

12. Is pooled molecular COVID-19 testing billed in the same way as individual testing?

Yes. Since the same molecular COVID-19 testing is ordered, performed and reported, pooled testing is billed in the same way using the same codes as non-pooled testing. While pooling can consume fewer reagents, it is not always the case that fewer tests will be performed with pooling. The efficiencies that arise from pooling are dependent upon identifying low prevalence populations and are offset by increased labor outlined above (e.g., changes in workflow and extra steps including specimen extraction and retention for further analysis; sorting specimens by site of origin to determine low prevalence and whether pooling is feasible; and retesting, as applicable where the pool is positive). Pooled testing is recognized as a means to significantly expand COVID-19 testing capacity and throughput and should be reimbursed no differently than the same tests performed individually.

13. What is multiplex testing and how is it used?

Multiplex testing helps providers detect multiple respiratory viral pathogens (e.g. SARS-CoV-2, Influenza A, Influenza B and Respiratory Syncytial Virus [RSV]) at the same time, using one specimen sample and the same instrument. Leading public health experts have noted the significance and importance of broad access to multiplex testing as a critical part of the country’s response to the upcoming flu season and the ongoing health challenges from the COVID-19 pandemic. Following the FDA’s authorization of the CDC’s Flu SC2 Multiplex Assay in July, several ACLA member laboratories have pioneered new multiplex tests to support our nation’s public health goals.

The distinction between SARS-CoV-2, influenza A, influenza B and RSV can be significant as they do not share the same treatment or public health implications. COVID-19, influenza and RSV are spread through respiratory droplets and can cause similar symptoms, including fever, cough and loss of smell. According to the Centers for Disease Control (CDC), patients may also experience concurrent respiratory infections, making our ability to identify these viruses in a single patient sample even more important. 

Multiplex testing also helps laboratories conserve important testing supplies, such as pipettes, swabs and reagents, all of which remain in high demand. Moreover, multiplex testing decreases the need for single-use tests and allows labs to provide more comprehensive results in a given time period.