The global diagnostics community has raced to meet the unprecedented need for tens of millions of tests for SARS-CoV-2, the novel coronavirus that causes COVID-19. In addition to our cobas® SARs CoV-2 test, many tests from other diagnostic companies have received Emergency Use Authorization (EUA) by the U.S. Food and Drug Administration (FDA), greatly improving our national testing capacity. No one company could come close to fulfilling the ever-growing global need for tests.
Given these tests were developed quickly and under emergency circumstances, it’s no surprise that people have questions and concerns about their accuracy.
You can think of test accuracy in two ways:
One thing to keep in mind is that no diagnostic test offers perfect performance. With any test, there will always be some false positives (the test says you have the disease when you actually don’t) and false negatives (the test says you don’t have the disease when you actually do).
To develop our test, we leveraged years of experience in creating high quality molecular tests. PCR (polymerase chain reaction) technology, which we use in our cobas SARS-CoV-2 test, is considered the gold standard for detecting the presence of the virus. We’ve striven to achieve high specificity and high sensitivity in our test, which is critical for the accurate diagnosis of COVID-19.
The limit of detection (LoD) is an important performance characteristic of clinical laboratory diagnostic, therapy monitoring and screening tests. LoD is the lowest quantity of a substance that can be distinguished from the absence of that substance with a stated confidence level. Studies have demonstrated that our test is able to detect very low levels of the SARS-CoV-2 virus with 95 percent certainty, and it does not detect other respiratory pathogens.
We expect, based on previous experience with similar PCR technologies to detect viruses, that the frequency of false positives and false negatives will be low.
There are several factors independent of accuracy that can lead to false positives or false negatives with any test, including our PCR-based test. Some of these include:
Accurate testing plays a critical role in slowing the spread of COVID-19. We will continue to work with laboratories around the world during the pandemic to collect data on the use of our test to ensure that its performance is consistent with our other PCR-based tests and to give healthcare providers and their patients confidence in their test results.