Approaches to improved influenza vaccination

Inactivated influenza vaccine (Ivac) has had an important impact on reducing attack rates of influenza and reducing the severity of illness amongst the vaccinees who still acquire infection. Ivac is most efficacious amongst young, otherwise healthy subjects and least effective against elderly at high risk. This is in part because Ivac does not appear to significantly reduce infection rates and in part because response rate and final antibody titer are lower in the elderly. Therefore Ivac does not eliminate disease in the elderly who are prone to complications when any virus replication occurs. Simultaneous administration of intra-nasal live attenuated influenza vaccine (Livac) and Ivac reduces the infection rate and thus illness rate amongst high-risk elderly. Presumably this is because of the ability of Livac to stimulate secretory antibody which neutralizes virus at the mucosal surface. Other approaches are examining the benefit of baculovirus recombinant vaccine or adjuvanted Ivac to determine if the higher serum antibody these vaccines produce compared to Ivac, will diffuse onto the mucosal surfaces and in a similar fashion, neutralize virus at that site.