In order to properly track and control the spread of COVID-19, we must develop diagnostic tests with high-throughput capabilities and excellent accuracy. Many politicians have used the term “flatten the curve” to note that it appears our infection rate is declining. States are beginning to ease economic restrictions while maintaining social distancing. With the data provided it does appear that the curve is flattening, but we still are lacking in testing capabilities. Only a small portion of people have been tested, as of May 13th there were 1.2 million individuals tested for COVID-19 in the state of New York. New York has an estimated population of 19 million people, meaning only 6.3% of the population has been tested. In order to have a safe reopening of our economies, we must continue to invest in our testing capabilities.
Currently, there are 69 manufacturers who have received Emergency Use Authorization (EUA) from the FDA to market their COVID-19 testing kit. Depending on their certification level, patient testing facilities can purchase and use these tests. There are an additional 26 test methods which have been developed by laboratories but due to their complexity they are not able to be marketed, and are only to be used by the developers of the test method. In total there are 135 laboratories nationwide who have notified the FDA that they have validated their own test and have either been granted or are pending EUA. Let’s take a look at some various testing methods and the manufacturers who have developed them.
Molecular Test
The FDA regards this as the most accurate form of testing. Molecular testing relies on an amplification method which detects the genetic material (RNA) of the virus. This method is highly accurate because it is a qualitative method rather than quantitative. This means that the test reports as either “positive” or “negative” instead of reporting a value of how much virus is present. Several big pharmaceutical companies including Abbott Laboratories, Roche, Hologic and Thermo Fisher have developed molecular test kits, these are not the only companies who have created test kits. Although these tests are highly accurate, they do require the use of expensive instruments which put low income areas/developing countries at a disadvantage.
Abbott Laboratories test is known as the RealTime SARS-COV2 Assay. Patient samples are collected through oral or nasal swabs. Abbott reports that samples for this assay can be self-collected by patients or by a health care provider. Their assay allows for 24-96 samples to be ran at once; in 24 hours over 470 patient samples can be analyzed. This product has received EUA from the FDA.
Antigen Test
Antigen testing detects the proteins which are located on the surface of the virus. A main benefit of antigen testing is their rapid result times. An unfortunate downfall to antigen testing is that positive results are often very accurate, but a negative result does not always mean the test is negative. Because of this the FDA recommends antigen testing always be followed up with a molecular test, especially if a patients symptoms correlate with infection. FDA has granted the only Antigen EUA to a company headquartered in San Diego; Quidel. Quidel’s test is named the Sofia 2 SARS Antigen Fluorescence Immunoassay (FIA).This test has an impressive 15 minute result time and a positive result correlates with a color change which is simple to interpret.
Antibody Test
When the immune system encounters something foreign, it creates antibodies against it which help fight off an infection. Antibody development often takes days, so this form of testing is not good for early stages of the infection because the body may not have made enough of the antibodies to be detected. The FDA does not recommend this form of testing for diagnosis, but it can instead be used to monitor the immune response to the virus and can help determine when a patient is recovering from the virus. Several companies have received EUA status for their antibody testing. Ortho Clinical Diagnostics received an EUA for their VITROS Immunodiagnostic products. Their VITROS system is able to detect multiple forms of antibodies which is great since different forms of antibodies are present at various times of an immune response. When compared to antigen and molecular testing this format takes much longer and requires more preparation and materials but unlike the other two it is able to track the progression of the infection.
Although the FDA has not officially approved any diagnostic testing, they have been very willing to grant EUA to companies. In order for FDA approvals to come out, the developers of the tests need to continue to gather data regarding the accuracy of the test and at what point of the infection they can be used. Improving our testing capabilities will drastically improve our ability to fight this infection and monitor the spread of the virus, especially if we see a second wave of the virus at another date.
Author
Jacob Cuyler 