Hemagglutinin (HA)

Hemagglutinin (HA) is a protein found on the surface of the influenza virus. Its main role is to help the virus attach to and enter human cells by binding to specific receptors on cell surfaces. This process is crucial for the infection to take hold. Because of its importance in infection and immune recognition, HA is a key target for flu vaccines and antiviral drugs. Variations in HA also help explain why flu viruses change each year, necessitating new vaccines. In summary, HA is a vital component that enables the flu virus to infect the host.