Live tissue-culture influenza vaccine.

With a view to improving the quality of live influenza vaccines (previously passaged on eggs) in the USSR, attempts were made to obtain vaccine strains of virus by recent tissue-culture methods.Strains of A2 and B viruses obtained from patients in influenza epidemics were isolated on chick embryos and cultured by serial passage on monkey-kidney tissue or skin-muscle tissue of human embryos; a variant strain was obtained by further passaging of tissue-culture virus fluid through chick embryos. These strains all became gradually adapted to the tissue-culture and were generally stabilized by the 10th to 13th passage.Intranasal insufflation of the vaccine into volunteers resulted in twofold to eightfold antibody increases in the great majority and gave rise to almost no reactions.Lyophilization of the strains with sucrose-gelatin or calf serum ensured the stability of the vaccines for periods of up to six months.