Influenza A virus A/Victoria/210/2009 X-187 (H3N2) hemagglutinin antigen (formaldehyde inactivated)

A seasonally-specific component of the influenza vaccine. The influenza vaccine, also known as the "flu shot", is a vaccine that protects against infection from the influenza viruses. Vaccines provide protection... Vaccines provide protection from influenza by exposing the immune system to the virus (or parts of the virus) which stimulates an immunological defence against future exposure to the virus, or "antigen".