With the apparent “confusion” and lack of clear and detailed information coming from the Vets Home, I spoke with a local scientist about test results and got some feedback on their interpretation of what is happening. I might still not be 100% there, but it was an interesting conversation.
Vet’s Home samples first tested positive, and now the majority are testing negative – so what does this mean? What questions should County Health be asking? First, don’t assume the first or second result must be wrong and the other correct because you might be picking the answer you want and not the right answer. Most diagnostic tests, both the antigen and PCR tests, now in use will remain accurate with the variant strains, and vaccination should not interfere with diagnostic or antibody tests. The antigen test looks for a part of the COVID-19 virus and gives quick results. The PCR test checks for the genetic material (DNA) of the virus and usually takes longer for a test result. The FDA has approved over 200 diagnostics tests and recently warned that several tests out of many do not work. In general, antigen tests are not as sensitive as PCR tests. Due to the potential for decreased sensitivity compared to PCR assays, negative results from an antigen test may need to be confirmed with a PCR test. Antigen tests are an essential tool in the overall response against COVID-19 and benefit public health. One of the main advantages of an antigen test is the test’s speed, which can provide results in minutes. The availability of these types of tests provides the ability to test millions of Americans rapidly. It is essential to understand the accuracy and relevance of testing. Both diagnostic tests may be subject to false-positive results, especially in low prevalence settings. What does low prevalence mean? It means low cases of COVID-19.
We have also added two attachments that help to explain this discussion.
Potential for False Positive Results with Antigen Tests
False Positives? An Epidemiologist’s Guide to COVID Test Terminology