Laboratory and clinical evaluation of new live influenza virus vaccines. Need for minimum requirements.

Recently, new methods for the selection of candidate live influenza vaccine viruses have become available. They are based on the characterization of the genetic material of these viruses and have been shown to correlate with attenuation for man. Adequately attenuated viruses have been obtained from various H3N2 strains using standard methods of attenuation for each strain. These vaccine strains met the criteria for live attenuated influenza virus vaccines: they were attenuated, non-transmissible and immunogenic. The use of modern methods of attenuation also allows rapid updating of live influenza virus vaccines. Laboratory methods used, the safety testing of candidate vaccines in animals and man will be discussed. There is an urgent need for standardization and for the establishment of minimum requirements and specifications.