Immunogenicity and safety of a novel IL-2-supplemented liposomal influenza vaccine (INFLUSOME-VAC) in nursing-home residents.

Abstract Influenza and its complications account for substantial morbidity and mortality, especially among the elderly. In young adults, immunization provides 70–90% protection, while among the elderly the vaccine may be only ≤50% effective; hence, the need for new, more immunogenic vaccines. We compared the safety and immunogenicity of a novel, interleukin-2 (IL-2) -supplemented trivalent liposomal influenza vaccine (designated INFLUSOME-VAC) with that of a commercial trivalent split virion vaccine in community-residing elderly volunteers (mean age 81 years) in winter of 2000/2001. Eighty-one individuals were randomly assigned to be vaccinated intramuscularly, either with the standard vaccine ( n =33) or with INFLUSOME-VAC ( n =48) prepared from the former. The two vaccines contained equal amounts of hemagglutinin (HA) (∼15 μg of each viral strain); INFLUSOME-VAC consisted of liposomal antigens admixed with liposomal human IL-2 (Lip IL-2) (33 μg=6×10 5  IU/dose). At 1 month post-vaccination, seroconversion rates (tested by hemagglutination inhibition) for the A/New Caledonia (H1N1) and A/Moscow (H3N2) strains were significantly higher ( P =0.04) in the INFLUSOME-VAC group (65 versus 45%, 44 versus 24%, respectively). Moreover, INFLUSOME-VAC induced a greater anti-neuraminidase (NA-N2) response ( P