The number of COVID-19 cases that the Oklahoma State Department of Health provides each weekday only reflects those who get a positive test.So that raises the question, how many cases does Oklahoma actually have? One doctor told KOCO 5 there could be thousands more."I estimate that there's probably five times as many cases out there than being reported," said Aaron Wendelboe, an infectious disease expert.Wendelboe said he bases that estimate on the percentage of people being hospitalized and the percentage of people dying. Again, it's his estimated guess."Certainly has some error because we don't know what we can't measure," Wendelboe said.Oklahoma health leaders agree with Wendelboe's estimated guess. "We do understand that there's going to be an underestimation of the number of positive cases," Oklahoma Commissioner of Health Lance Frye said.Health officials said testing for COVID-19 has changed since last year."There are take-home options to get tested now, which, unfortunately, is good for access, but it doesn't always get us the information we need to understand the level of COVID we have in the community," Deputy Health Commissioner Keith Reed said. "A lot of those are being used and not being reported.Doctors said the transmission rate has doubled over the last couple of months.