Since the beginning of the pandemic, the United States has reported more than 10.3 million cases of COVID-19. Cases may be either “confirmed” cases or “probable” cases. The reason for this is that the Centers for Disease Control and Prevention recommends that states separate their data into confirmed and probable cases. But what, exactly, is the difference?

A confirmed case is a person whose illness has been diagnosed as COVID-19 using a Food and Drug Administration approved test. The most common is the RT-PCR test. RT-PCR stands for “real-time polymerase chain reaction.” The RT-PCR is currently the “gold standard” for infectious disease molecular diagnostics. Someone with a lab-confirmed RT-PCR test of COVID-19 doesn’t have to show symptoms or have exposure to a known case. They just need a positive result from an approved test.

The definition of a probable case is a bit more complicated. Southeastern Idaho Public Health defines a probable case based upon national definitions/classifications, as:

— A close contact of a confirmed case, who has symptoms themselves but for whom we do not have a positive test result.


— An individual who has symptoms of COVID-19 and also has a positive antigen test result. Antigen tests, more commonly known as a rapid COVID-19 test, is a newer type of test. These tests are highly reliable in people who exhibit symptoms; on the national level, they are counted as probable.

“We treat confirmed and probable cases identically (as is done nationally and in the rest of Idaho),” said Maggie Mann, Southeastern Idaho Public Health director. “PCR testing has been, unfortunately, in limited supply. Antigen tests are often more readily available.”

Why is it important to count probable cases? First, the CDC recommends that both confirmed and probable cases of COVID-19 should be “included in the ‘case’ count.” Second, it provides more context for COVID-19 data.

“Counting probable and confirmed cases helps to ensure we have a uniform system in place for providing an accurate look at how this disease is affecting our community,” Mann said.

For Southeast Idaho specific information about the novel coronavirus, visit

For Idaho-specific information about the novel coronavirus, visit

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SIPH has a COVID-19 Hotline to field questions from the community and is open Monday-Friday from 9 a.m. to 4:30 p.m. You can reach the hotline at 208-234-5875.