Antibody response toward influenza virus neuraminidase protein after low dose intradermal versus intramuscular Fluzone vaccination in humans

Influenza is a contagious respiratory illness which results in hospitalization of more than 200,000 people and the death of around 36,000 people in the United States every year. The best way to reduce the impact of influenza is through immunization. Current seasonal vaccination is designed to induce a neutralizing antibody response against the viral envelope protein hemagglutinin (HA). An antibody response toward influenza viral envelope protein, neuraminidase (NA), has also been shown to contribute toward protection from influenza disease. Low-dose intradermal vaccination has been proposed as a vaccine-stretching measure. Intradermal influenza vaccination may elicit a strong anti-NA antibody response, despite the vaccine containing less NA than HA, because of the abundant antigen presenting cells found in the skin. This research compares the magnitude of antibody response to influenza virus protein NA elicited by the influenza vaccine (Fluzone?, 2004-2005) administered intramuscularly (standard dose) and intradermally (1/5 dose and 1/25 dose). A neuraminidase inhibition assay was used to determine the NA inhibition antibody titer of vaccinated subjects against A/New Caledonia/20/99 (H1N1) and A/Wyoming/03/03 (H3N2). It was also used to detect cross-reactive NA-specific antibodies against a novel avian influenza strain A/Turkey/Ontario/6625-1/98 (H6N1). Results showed that virus-specific NA inhibition antibody titers were similar among vaccination groups and that the seasonal influenza vaccine produces cross-reactive antibodies to influenza virus NA protein