It is not definite that they have the illness.
A statement relased to KSN/KODE from OSDH says:
OSDH is working with health care providers and federal partners on coordinating testing for two individuals that meet the criteria for persons under investigation.
It is important to note that a person under investigation is not a case of novel coronavirus. The Oklahoma State Department of Health does not disclose demographic or other information during investigations while laboratory testing is pending.
Even if a case of novel coronavirus in an Oklahoma resident, it is important to note the risk to the general public is low. Public health officials identify possible contacts to a person under investigation and notify them to assess their exposure risk.
At this time, all confirmed US cases have a history of travel to Wuhan, China, which is the epicenter of the outbreak. Although five cases have been identified to date, of 110 persons under investigation identified in 26 states, laboratory testing was negative for 32 individuals. Testing is pending for the remaining 73.Oklahoma State Department of Health