Intranasal immunization with inactivated influenza vaccine.

The development of improved vaccines against epidemic and pandemic influenza virus infection remains a priority in vaccine research. Killed vaccines given by injection are both cost-effective and induce immunity; however, their limitations are well known. Live vaccines have been in development for many years, but difficulties and safety concerns have prohibited their licensing in Western countries. However, the newer technologies of vaccine development, including DNA vaccines and attenuated virus vaccines produced by reverse genetics, remain a hope for the future. With these problems in mind, emphasis has been given to the development of inactivated vaccines that are administered intranasally, either as repeated doses of saline vaccine or in conjunction with suitable carriers or adjuvants. This review describes these latter developments and concludes that this approach offers advantages and should be vigorously researched.