AUSTIN (KXAN) — The Texas Department of State Health Services changed the way it reports the state’s COVID-19 positive rate Monday, adding two additional positive rates to its dashboard.
Until this point, the state has calculated the positive rate based on the number of new confirmed cases over the past seven days divided by the number of new tests. This rate — referred to as the ‘legacy method’ — will continue to be reported. As of September 14, that rate stands at 8.15 percent.
The legacy method served as a “reliable proxy” for most of the pandemic, but became less reliable in August when a surge in backlogged cases was reported. This caused new cases and new test results to get out of sync, DSHS says, “leading to large swings in the positivity rate and the need to reevaluate methods to calculate it.”
DSHS says it will now primarily rely on the first new rate — known as the Specimen Collection Date Positivity Rate. It uses the date the person was tested for COVID-19. For example, if a person got tested on September 1 and received a positive result on September 14, DSHS would add one case on September 1 when calculating this new positive rate. Thus, the rate will fluctuate as new test results come in.
In a press release, DSHS said this new method “provides the most accurate view of the pandemic’s effect over time.” The increased accuracy is because of the removal of the lag time between when a person is tested and when a case is confirmed. The state says the rate “will not be skewed by delays in reporting test results to the state.”
The second new rate uses the date when lab results are reported to the state. All three rates are only calculated using molecular test results. Antibody and antigen tests do not factor into the rates.
“These enhancements are part of our continuous effort to improve the information we present,” DSHS Commissioner Dr. John Hellerstedt said in a press release Monday. “As the COVID-19 pandemic evolves, so must the data we share. Our information must provide the clearest possible picture of what is happening now and what has occurred in the past. The trends in this and other data shape our understanding of what to expect in the future.”