Jim Vondruska/Reuters
- The H5N1 bird flu virus has infected a third person in the US, this time with respiratory symptoms.
- The new patient's cough and sore throat could help the virus get better at infecting humans.
- Experts fear the US is missing critical opportunities to check the virus's DNA for new mutations.
The H5N1 bird flu virus has once again infected a human. But this time, the unlucky patient had a cough and a sore throat, which is a new milestone for the virus's spread in the US.