The Problem With COVID-19 Testing

Covid-19 Testing Confusion

One of the most frequent questions we are getting is getting a Coronavirus test. Between casual conversations, the press, the web and social media it can be very confusing to figure out what information is correct, incorrect or outright false. To make things more difficult, it seems everything about testing is changing on a daily basis.

To help, here is a basic explanation of the types of tests that can be done, and what the test results mean. Again, this is the most current accurate information I can share, and subject to changes in the future as we learn more about Covid-19.

There are essentially two types of tests a patient can get for Covid-19: Molecular (PCR)/ Antigen and Serological (Blood)/Antibody

1. Molecular testing is the predominate test type being used, and at this time the most important. This is the nasal swab test, often obtained in drive-up testing centers. The nasal swab molecular test is used to determine if someone has active Covid-19 virus infection. At present, most of this type of testing takes 24-72 hours to get the result because they are being sent to special labs located throughout the state. The good news is these tests are becoming more available, and the technology is advancing rapidly so that soon this type of test will be able to be performed at clinics and locations obtaining the specimen, with results in 30 minutes or less. Premier anticipates being able to provide this by June. Today, we can obtain the specimens, and send them off to the special labs, and call with the results as soon as they are available.

2. Serologic (Blood) testing is the hot topic now, with much confusion, and even more false information. The blood test does not test for the Covid-19 virus, but our bodies response to a Covid-19 infection. When we are infected with any illness, or body produces antibodies to fight this infection off. The blood test is for these antibodies, not the actual infection. It means that sometime in the past, 1-4 or more weeks ago a person had Covid-19.

Blood / Antibody testing can currently be performed. However, of the over 180 different companies promoting this testing, as of yesterday only 8 have been approved and deemed accurate by the FDA. Of all the testing, the FDA has allowed “emergency use” of non-FDA approved tests but restricted them to labs designated as High Complexity classification: think big laboratory operations, and hospitals for the most part. So, beware! There is a high probability anyone providing antibody tests performed at their clinic are not approved, and not allowed unless actually performed by a hospital lab or other high complexity licensed lab. The results could be meaningless or worse!

Inaccurate antibody tests results are a big cause of concern and alarm. These false results can be dangerous to individuals, and others who are using this information. Test specificity sounds like a test is specific for a disease. 90% specific sounds even better, right? Well, not really. Test specificity is a measure of how many negative samples actually test negative. A 90% specificity means that there is a False Positive 10% of the time. This could erroneously lead a patient to believe they have had the infection, and have antibody protection against this infection, when 10% of the time they do not.

Just to make things even murkier, we do not know if having these antibodies will even protect against us from getting Covidagain. Sort of like the flu; a person could get the flu once or twice a year every year. Knowing how to interpret these tests and what action is safest is just as important as the reliability and accuracy of them. If both are in question, the usefulness of the antibody test becomes worse.

Premier now offers Molecular testing to determine if a patient has active Covid-19 infection. The results are usually available in 24-48 hours, but up to 4 days. These labs are being sent to a special lab for processing in Austin. Antibody testing will be important in the future, once the lab capabilities and accuracy improves, and once we know exactly what it means.

Thank you for reading and stay safe!

John Hamilton, MD, FACEP / CEO and President