It is important to understand the indications, benefits and limitations of the different types of COVID-19 tests available.

Kevin Thornal President, Diagnostic Solutions

With the highly infectious Omicron variant spreading widely in the U.S., we are in the midst of yet another surge in the COVID-19 pandemic and with a renewed and even more heightened need for reliable testing to help control the spread.  

Fortunately, at this stage in the pandemic, when we are all anxious to move forward, most people recognize how important testing is to keeping their friends, families and communities healthy. However, as we are seeing in the news, it is equally important to understand the indications, benefits and limitations of the different types of tests available. Because of how quickly Omicron is spreading, even among fully vaccinated people, this is even more true when considering tests for use in those who are asymptomatic or may be presymptomatic. Failure to detect even a small number of individuals with active infections (false negative cases) could potentially result in the exposure of many others.

Rapid antigen tests are convenient as they can be used in the home and provide results quickly. But while positive antigen test results are generally reliable, these tests are also associated with a relatively high rate of false negatives.

Molecular tests, including PCR tests, received Emergency Use Authorizations that specifically recognize these tests’ ability to detect virus in both symptomatic and asymptomatic individuals. These authorizations include Hologic’s own Aptima and Panther Fusion SARS-CoV-2 assays, and are based in part on data demonstrating that these tests display very high sensitivities, in some cases higher than 99%. 1,2. The limit of detection for these assays are the lowest of any fully automated, high-throughput test evaluated with the United States FDA SARS-CoV-2 reference panel, as documented in a report published by the FDA.3  

For that reason, many physicians and the U.S. CDC recommend that people who are experiencing COVID-like symptoms but get a negative antigen test result follow up with a molecular test rather than assume they are not infected. FDA also issued a statement in late December that antigen tests may be less sensitive to Omicron than to earlier variants.4 Because molecular tests are more sensitive, it is also possible that they may detect the presence of virus earlier in the course of infection than less sensitive tests.

The bottom line is that molecular tests offer the greatest sensitivity and therefore the most reliable results. When it comes to protecting the health and well-being of yourself and those you love, being sure is paramount.