Bird flu risk to humans is low right now, but "things can change," doctor says

After bird flu jumped to dairy cows in March, the H5N1 virus has spread among cattle across nine different states, stoking fears about the potential impact of the virus on humans. 

Public health officials are closely monitoring for any signs H5N1 is mutating into a form that could spread from human to human, CBS News chief medical correspondent Dr. Jon LaPook told "CBS Mornings" on Friday. 

"There's no evidence that has happened yet, but that's the big concern," he said.