Clinical and serological response in humans following immunization with gripax influenza vaccine

A commercial trivalent formol-inactivated influenza vaccine (Gripax) was tested. The vaccine consisted of equal amounts of A/England/321/77 (H₃N₂), B/Hong Kong/8/73, and A/USSR/99/177 (H₁N₁) strains. One hundred four females were injected intramuscularly. Eighty-eight (74.6%) were 17–24 yr old and 16 (15.4%) were 29–45 yr old. Seventy subjects were immunized with 1,200 IU, 24 with 1,680 IU, and 10 with 2,400 IU. A follow-up for adverse side effects was carried out during 72 hr following vaccination. There was no absence from work or school, nor did the subjects develop any systemic symptoms (fever and malaise). Local reactogenic effects were minor and included painless erythema and induration of low degree, which were observed in small numbers of the recipients and lasted for no more than 24–48 hr. Localized, axillary lymphadenopathy was noted in one subject. Seventy-four paired sera samples were tested for hemagglutination inhibition (HI) response. A highly reactive response to A/England and B/Hong Kong strains was observed, as evidenced by an at-least fourfold increase of titers. There was no significant change when a dose of 400 IU or more was given: An 83.6% and 89.4% response was, respectively, recorded for A/England and 69.0% and 73.6%, respectively, for B/Hong Kong. However, when the dose of A/USSR was increased, the response was significantly elevated from 56.0 to 84.2%. All the sera tested for neuraminidase inhibition antibody showed a satisfactory response. Regardless of the dose, a single administration of the vaccine sufficed to confer a high degree of immunity against the “old” circulating strains: 94–100% against A/England and 79–90.9% against B/Hong Kong. Immunization with 400 IU of the recent strain A/USSR conferred immunity in 50.9% of the cases, whilc the administration of a dose equal to or larger than 560 IU elicited a far higher rate of immunity-89.4%. The high quality of the vaccine is evidenced by the conversion rate from nonimmune to the immune state, as well as by the lack of undesirable side effects.