Comparison of new triton X-100- and tween-ether-treated split-treated vaccines in children.

Split-product vaccines (SPVs) combine the desirable properties of no systemic reactogenicity and adequate immunogenicity when two doses are given. We compared a new Triton X-100 SPV (Connaught Laboratories, Inc.) with the commercially available Tween-ether SPV (Parke-Davis & Co.) in 76 children and young adults 2 to 25 years old; there were 39 and 37, respectively, in each vaccine group. Both vaccines contained influenza A/Brazil/78, A/Texas/77, and B/Hong Kong/72 (7 microgram of hemagglutinin for each strain); two doses were administered 1 month apart. Among persons seronegative by the hemagglutination inhibition test, the geometric mean antibody titers rose to approximately 100 after the first vaccination for influenza A/Brazil/78 and A/Texas/77. For B/Hong Kong/72, however, seronegative recipients developed lower geometric mean titers of approximately 32 after one immunization. Against the new B/Singapore/79 strain neither SPV stimulated adequate cross-reacting hemagglutination inhibition antibody (geometric mean titers of approximately 10). In conclusion, the new Triton X-100 SPV appears to be comparable to the ether-treated SPV in primed subjects. Further studies in unprimed children should be done to confirm this impression. In addition, it would be advisable to study other dosage regimens in unprimed children with these SPVs.