A second Missouri healthcare worker who had contact with a hospitalized patient infected with bird flu developed mild respiratory symptoms but was not tested for the virus, U.S. officials said on Friday.

In its latest update, the CDC said the second health care worker wasn’t tested for influenza because the illness had resolved before the investigation began. The second health care worker will be offered the same blood test to determine if that person has antibodies for the bird flu virus.

A third close contact of a patient in Missouri who was hospitalized with H5N1 bird flu has reported that they also experienced symptoms, the US Centers for Disease Control and Prevention said Friday.