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Free home testing kits available,
Q: I’m hearing lately about at-home tests for COVID-19. Are those reliable?
A: Fortunately, cases of COVID19 have decreased since the surge seen last year, but the level of transmission in our community remains substantial, according to the U.S. Centers for Disease Control and Prevention’s COVID Data Tracker. Positive daily tests in Hamilton County last month were between 50 and 60 cases a day. These numbers, however, probably represent an undercount of infected individuals since many people can have COVID-19 but not have any symptoms (be asymptomatic) and not necessarily think they have a need to test.
In a study published earlier this year in the Journal of the American Medical Association, an analytical model suggested that asymptomatic individuals transmitted more than half of all COVID-19 infections. More recently, the CDC reported asymptomatic transmission can occur in 15% to 70% of cases. The CDC’s model used several scenarios, including viral transmissibility, to calculate their percentages. These studies are a reminder that there is a risk of transmission from people who do not have symptoms. Rapid, point-of-care screening can identify asymptomatic cases and help interrupt SARS-CoV-2 transmission, particularly in communities where risk of transmission levels is substantial or high.
There are several COVID-19 tests available for both screening and diagnosis. Screening tests are intended to identify people who are asymptomatic and do not have known, suspected or reported exposure. Identifying these cases can prevent further transmission. Diagnostic testing is intended to identify current infection in people with or without symptoms who have had a recent known or suspected exposure. Available tests look for genetic material of the virus, called polymerase chain reaction, or PCR, while others test for viral proteins produced by the virus, such as an antigen test.
Both kinds of tests require a sample from the nose or saliva. A PCR test is highly sensitive (meaning few false positive results) and specific (few false negative results).
Previously, a PCR test could take 24 to 48 hours to process a result, however many PCR tests are now rapid, providing same-day results. An antigen test is also a rapid test, but it is not as sensitive as PCR testing. Either test is a valuable screening and diagnostic tool to aid in the control of community transmission.
We know access to testing, need for rapid results and ease of testing are effective strategies to decrease transmission. Testing could be much easier and convenient if people are able to do it at home and know results right away. A person doing an at-home COVID-19 test can find out if he or she is positive and immediately self-isolate, helping to stop the spread.
Such tests are now available for people to purchase over-thecounter (BinaxNow from Abbott Laboratories and QuickVue by Quidel) and more (including one from Ellume) are expected in the next couple of months. Home testing will help identify people with COVID-19 infection, adding another effective strategy in the fight against COVID-19 community transmission.
This week, the Hamilton County Health Department, together with community partners, the CDC and the National Institutes of Health, launched the “Say Yes COVID Test” campaign in our county. This campaign will offer free, at-home COVID testing to residents of Hamilton County. Researchers will assess if self-administered testing helps reduce the spread of the virus. Visit the program website at covidtest chattanooga.org or call the hotline 423-209-8383 to get your kit.
Fernando Urrego, M.D., is the interim health officer at the Chattanooga-Hamilton County Health Department and a member of the Chattanooga-Hamilton County Medical Society.