The CDC has revealed the red flags it is monitoring for that suggest that bird flu was about to become the world's next pandemic.

The Centers for Disease Control and Prevention is keeping close eye on pandemic indicators amid bird flu cases arising in the United States.

The CDC's analysis revealed changes in the hemagglutinin (HA) gene, a critical component for the virus's ability to attach to host cells. The mutations "were not found in virus sequences from poultry samples collected on the patient's property, suggesting the changes emerged in the patient after infection," the CDC stated in its December 26 update.