Intranasal or inhalational administration of virosomes

The present invention provides a composition of influenza virosomes comprising reconstituted envelopes of said virus, wherein the viral envelopes are entirely derived from influenza viral particles, wherein no lipid is added from an external source to the reconstituted virosomes, wherein the virosomes comprise the influenza antigens haemagglutinin and/or neuraminidase or derivatives thereof, wherein no separate adjuvant and/or immune stimulator is added to the composition, and wherein the composition is for intranasal or inhalational administration, which composition is characterized in that a single intranasal or inhalational administration to a human being is sufficient for the induction of a systemic immune response and/or a local immune response and/or a cytotoxic lymphocytes response against said influenza antigens, which systemic response is in accordance with the CHMP criteria for influenza vaccine, and wherein the dose of haemagglutinin per viral strain per intranasal or inhalational administration is lower than or equal to 30 μg. The invention also provides the use of reconstituted influenza virosomes for the manufacture of said composition, and accordingly manufactured vaccine formulations. The invention also provides methods of inducing an immune response against an influenza virus in a host, and methods of preventing an influenza viral infection in a host, each comprising intranasal or inhalational administration of influenza virosomes comprising reconstituted envelopes of the influenza virus to the host.