CONTACT: For members of the media, please contact:
Laura Mayes, City of San Antonio (210) 207-1337
Michelle Vigil, City of San Antonio (210) 207-8172
For questions from the general public, please contact:
COVID-19 Hotline (210) 207-5779
SAN ANTONIO, TX (July 16, 2020) - At the request of the Texas Department of State Health Services (DSHS), Metro Health is now separating COVID cases that were confirmed by a positive molecular test (PCR) from those that were detected by a positive antigen test combined with COVID-19 symptoms, otherwise known as “probable cases.” Antigen tests were approved by the FDA for emergency use on May 8 and July 2, 2020, and they are considered very accurate in detecting the presence of COVID-19 in people with symptoms. The CDC includes positive antigen test results in its national count of COVID-19 cases, as does Metro Health in Bexar County counts. However, the State of Texas does not include antigen test results in its COVID-19 dashboard counts, despite collecting this data from local health departments and reporting it to the federal government.
“Probable cases do not mean ‘maybe’ cases of COVID-19,” said Dr. Colleen Bridger. “Antigen tests are FDA approved, and positive tests are highly accurate. San Antonio is one of only three Texas cities collecting and reporting this data per the CDC guidelines, but the State of Texas wants apples-to-apples comparisons between Texas cities.”
Antigen tests quickly identify people who are currently infected with the coronavirus by detecting proteins from the virus in nose and throat secretions. This is the same technology used in your doctor's office for rapid strep testing. By contrast, a PCR test, looks for genetic material.
When the FDA authorized the emergency use of antigen tests in the detection of COVID-19, it stated the following:
This latest FDA authorization is for an antigen test, which is a new type of diagnostic test designed for rapid detection of the virus that causes COVID-19. Each category of diagnostic test has its own unique role in the fight against this virus. PCR tests can be incredibly accurate, but running the tests and analyzing the results can take time. One of the main advantages of an antigen test is the speed of the test, which can provide results in minutes. However, antigen tests may not detect all active infections, as they do not work the same way as a PCR test. Antigen tests are very specific for the virus, but are not as sensitive as molecular PCR tests. This means that positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection. With this in mind, negative results from an antigen test may need to be confirmed with a PCR test prior to making treatment decisions or to prevent the possible spread of the virus due to a false negative.
Antigen tests should not be confused with antibody tests, which detect a specific antibody in the blood that indicates the body’s response to a new or recent infection of COVID-19. Antibody tests, which are considered much less reliable that molecular and antigen tests, are not reported in San Antonio Metro Health’s case counts.
In response to the request from DSHS, Metro Health has separated confirmed and probable case counts in the data posted daily to the City’s COVID-19 website.
COVID-19 Cases by Case Type (As of 7/15/2020)
*Confirmed cases defined as cases that have a positive molecular (PCR/NAAT) test result. Probable cases defined as symptomatic cases that have a positive antigen (FIA) test result.
Posted on 7/15/2020 at 7:00 PM.
Given the validity of antigen testing, San Antonio Metro Health will continue to report probable cases in its total case counts. Metro Health also conducts case investigations and contact tracing for probable cases.
“To be clear, this is not an ‘error’ in Metro Health’s reporting,” said Dr. Bridger. “This is a disagreement over what should be reported in total counts. We will continue to align our definitions with those from the CDC and the Texas Department of State Health Services, while honoring the state’s request to separate probable cases.”
FOUR WAYS TO SIGN UP FOR COVID-19 ALERTS
- Download the Ready South Texas app, available in the iTunes and Google Play stores
- Text COSAGOV to 55000 to receive SMS text message updates
- Follow @COSAGOV on Facebook, Twitter and Instagram
- Bookmark covid19.sanantonio.gov