The addition of new antigen test results led to a higher-than-normal coronavirus case count Thursday, health officials say, and they're expected to be higher in the days ahead.
Arizona Department of Health Services reported 1,753 new confirmed cases of coronavirus Thursday. It's a large jump after the most recent daily counts being in the hundreds.
In a blog post Thursday morning, ADHS Director Dr. Cara Christ said Arizona will be reporting higher numbers for several days as "a result of advancements in testing... (including) recently classified positive antigen cases dating back over the previous several months."
Up until this point, a person who received a positive antigen test result was only added to the state's count if they had known COVID-19 exposure or exposure to someone with symptoms of the virus. Some positive antigen test results were not added to the count because they did not report having known contact with COVID-19.
"Moving forward, we are expanding how we define cases to include anyone with a positive antigen test in the probable case category, which is consistent with the recently updated national case definition for COVID-19 from the Council of State and Territorial Epidemiologists," Dr. Christ wrote.
Late last month, another antigen test was authorized by Food and Drug Administration, detecting if a person is infected "by looking for specific parts of the virus from a respiratory sample (like a nasal swab)." The tests have become more widely used around the country, as well as in Arizona, including the University of Arizona.
Dr. Christ wrote that "antigen tests may not be as accurate or able to run as many patient samples per day. However, the quick results provide the ability to rapidly triage and make decisions."
Dr. Christ also noted that "the use and reporting of different tests continues to evolve as we increase our understanding of COVID-19."