Few People Have Existing Immunity to H5N1 Bird Flu: CDC Study

Study analyzed blood from hundreds of people.

Poultry in a file image. Jamie McDonald/Getty Images

Many Americans do not have existing immunity to the highly pathogenic avian influenza, a new study indicates.

The U.S. Centers for Disease Control and Prevention (CDC) collected blood from 489 people and tested their blood for antibodies against clade 2.3.4.4b A H5N1, a strain of the avian influenza that is currently circulating in the United States.