Immunologic Response of Extremely Premature Infants to Tetanus, Haemophilus influenzae, and Polio Immunizations

OBJECTIVE: To determine whether extremely premature infants have immunologic responses to tetanus toxoid, Haemophilus influenzae type b polysaccharide and polio vaccines similar to those of full-term infants. INFANTS AND METHODS: Sixteen extremely premature ( 0.01 IU/mL), HbPS (82% vs 87%, > 1.0 microgram/mL), and polio serotypes 1 (85% vs 80%, > or = 1:8) and 2 (100% vs 100%, > or = 1:8). Preterm infants were less likely than full-term infants to have protective levels of neutralizing antibody to polio serotype 3 (31% vs 90%, > or = 1:8). CONCLUSIONS: Extremely premature infants have adequate antibody responses to tetanus and HbOC antigens but may have diminished responsiveness to serotype 3 polio vaccine.