Methods that stimulate a protective immune response in a subject include a portion of a protein from a naturally occurring viral hemagglutinin, wherein the protein portion includes at least a portion of a globular head and at least a portion of at least one secondary structure that causes the globular head to essentially retain its tertiary structure, and wherein the protein portion lacks a transmembrane domain, a cytoplasmic domain and an HA2 subunit. Compositions administered to the subject can further include a carrier and can be administered in single or multiple doses.