Reactions and serologic responses after administration of inactivated monovalent influenza A/swine virus vaccines. II. Immunization of children with influenza A/New Jersey/X-53 virus vaccines.

Reactivity and immunogenicity of two inactivated, zonally purified, ether-extracted, influenza A/New Jersey/X-53 subunit virus vaccines were studied in 103 children three to 18 years of age. Children aged nine years of younger received doses of 100 or 200 chick cell-agglutinating (CCA) units, and those older than nine years received doses of 200 or 400 CCA units. Vaccines were given intramuscularly. Two doses were given at intervals of four weeks. The vaccines were minimally pyrogenic, causing only two instances of temperatures of greater than 100.0 F. Other systemic reactions were observed infrequently. Tenderness at the site of injection occurred relatively frequently but was of no medical consequence. The geometric mean titers of homologous antibody, which ranged from 1:52 to 1:75 after administration of two doses, were statistically equivalent in all treatment groups. Titers of antibody of greater than or equal to 1:40 to the influenza A/New Jersey/8/76 virus strain were achieved by 88% of the vaccinees. We concluded that two doses of ether-extracted, subunit influenza A/New Jersey/X-53 virus vaccine were well tolerated and, when given at least four weeks apart, were serologically effective for immunization of children aged three to 18 years.