Preparation and evaluation of a zonal purified influenza vaccine gripax

A highly purified influenza vaccine was prepared on a large scale. The inactivated whole virus vaccine fulfills the requirements of the National Institutes of Health, Bethesda, for influenza A and B vaccines. The three strains of influenza virus, A/England/321/77, B/Hong Kong/8/73, and A/USSR/99/77, used for the vaccine, were chosen in accordance with the demands of the WHO and the Israel Ministry of Health for 1978 to 1979 and 1979 to 1980. Virus strains were grown in the allantoic sac of embryonated eggs, inactivated by formalin, and purified by zonal centrifugation in sucrose. Each dose of 0.5 ml contained 1200 international units (IU) of influenza antigen (400 IU of each strain). The vaccine is higly immunogenic as demonstrated by potency tests in mice. Its immunogenicity was higher than that of commercial vaccines of a similar nature purchased at random in local pharmacies. A high dilution of 1:3125 still elicited HI antibodies in mice. No residual egg‐protein contamination was detectable by sensitive immunological methods. Total protein concentration was 80 μg protein per dose of 1200 IU, ie 15 IU per μg of protein as compared to 5–8 IU per μg of protein in the commercial vaccines tested by us. Purity of a vaccine is of major importance for the prevention of adverse side effects.