Information is changing by the hour and science is evolving daily to bring us a better understanding of the behavior of this virus, how we can most effectively test for it and react to the results of those tests. Here is a helpful breakdown of current terms and information related to COVID-19 testing: Diagnostic testing for COVID-19 is intended to identify current infection in individuals and is performed when a person has signs or symptoms of COVID-19, or when a person is asymptomatic but has recent known or suspected exposure to COVID-19. Diagnostic tests are medically necessary to guide clinical decision-making for individuals. Current diagnostic tests are PCR tests or antigen tests—find more information about testing types in the question below on this page.
Public health screening for COVID-19 is intended to identify infected people who are not showing symptoms and don’t know or think they’ve been exposed to COVID-19. Public health screenings are performed to identify people who may be contagious so that measures can be taken to prevent further transmission. Scientists are still studying which type of COVID-19 test is most appropriate as a public health screening. Public health departments are charged with making this decision for their respective communities.
- Find more information from the CDC.
- Learn more about public health testing in our area in the question below on this page.
The positivity rate is increasingly being used as a marker to guide community decisions like school openings. The positivity rate is defined as the percentage of COVID-19 tests performed that are positive in each population. Many public health experts believe that our communities should aim for a positivity rate of 5 percent in order to consider resuming “normal” activity. The positivity rate gives us an idea of how well we are controlling the spread of the virus AND how many people are being tested.
Testing accuracy is also important to consider. COVID-19 testing results are not 100 percent accurate and there are many false negative test results—meaning you may get a negative result when you do, in fact, have COVID-19. False negative test results are especially common with antigen testing, though this testing option is increasingly being used by healthcare providers because of its results can be determined more quickly. To make matters even more complicated, the accuracy of COVID-19 test results is impacted by when in the course of a person’s illness or exposure the test is performed—for example, PCR tests appear to be most accurate 5-7 days after exposure.
Symptoms may help guide your doctor’s recommendations more than test results due to questions of testing accuracy. For example, when flu season arrives each year and patients show key symptoms of influenza, medical providers are likely to treat the illness as the flu, regardless of the results of the flu test—the same is true with COVID-19.
Testing capacity is something we continue to focus on as well. At any given time, our communities have different capacity to conduct an appropriate number of diagnostic and public health screening tests to properly manage the pandemic. In an ideal scenario, testing would be available for all members of a community on a regular basis, offering the ability to identify those who should isolate from others to prevent transmission of the virus. In the absence of an ideal testing scenario, the importance of social distancing and wearing masks cannot be over-emphasized.