As the Centers for Disease Control and Prevention (CDC) explains, bird flu is a disease caused by the influenza A virus. At the same time, recent CDC data shows that seasonal influenza A is rising across the U.

Seasonal influenza vaccines triggered protective immune responses against the H5N1 avian influenza virus primarily in younger people, indicating its potential use as a first line of defense during an eventful pandemic.

The bird flu virus that killed 20 big cats in Washington and a pet cat in Oregon and is circulating among cows, poultry and wild birds isn't yet a threat to the general public, experts say. Why it matters: The first human death from bird flu isn't indicative of an imminent crisis,