Evaluation of a two-dose regimen of influenza A/New Jersey/76 subunit virus vaccine in three- to 10-year-old children.

Fifty-one Caucasian, middle-class children (aged three to 10 years) from the suburbs of Hartford, Connecticut, were immunized with two subcutaneous doses each of 200 chick cell-agglutinating units of influenza A/New Jersey/76 subunit virus vaccine/0.5 ml. The reactivity of the vaccine was negligible, and there was no increase in reactivity with a second dose. Administration of a single dose resulted in seroconversion in one-third of the subjects. Two weeks following the second dose, 84% of the children had reciprocal titers of hemagglutination-inhibiting antibody of greater than or equal to 10, and the geometric mean titer was 51. There was no significant difference in antibody response according to age. We concluded that inoculation of two doses of subunit virus vaccine is a safe and effective means of inducing a significant antibody response. The levels of antibody required for protection and for duration of antibody response are not known.