2702. Infants Vaccinated with a Fully-Liquid DTaP-IPV-Hib-HepB Vaccine Are Protected During the High-Risk Period for Haemophilus Influenzae Type B Disease

BACKGROUND: DTaP-IPV-Hib-HepB is a fully-liquid, combination vaccine (Vaxelis™) approved for vaccination in infants and toddlers against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis and Haemophilus influenzae type b (Hib). Safety and immunogenicity were evaluated in 4 Phase III, randomized, active-comparator controlled clinical trials (Protocols 005 and 006 in the US [Control: PENTACEL™] and Protocols 007 and 008 in the EU [Control: INFANRIX™ hexa]). The vaccine, studied in >6,800 children, has an acceptable safety profile generally similar to that of control vaccines (Xu, PIDJ, 2019; 38:439–43). DTaP-IPV-Hib-HepB includes polyribosylribitol phosphate (PRP) conjugated to outer membrane protein complex of Neisseria meningitidis (OMPC) that elicits a rapid response to Hib. METHODS: Data from these studies provide a summary of the anti-PRP responses of DTaP-IPV-Hib-HepB compared with Control. RESULTS: After the infant series, the percentage of participants who achieved short-term and long-term protective antibody thresholds for PRP (i.e., anti-PRP titer ≥0.15 μg/mL and ≥1.0 μg/mL, respectively) were higher in DTaP-IPV-Hib-HepB recipients compared with Control. A high level of protective responses (96.6% ≥0.15 μg/mL and 72.9% ≥1.0 μg/mL) were seen after the second dose in the 008 study of the 2 infant series followed by toddler dose hexavalent vaccination schedule (2 + 1). Across all 4 studies, anti-PRP titers were higher in DTaP-IPV-Hib-HepB recipients (91.4% ≥0.15 μg/mL and 46.8% ≥1.0 μg/mL) when compared with Control (63.4% ≥0.15 μg/mL and 17.1% ≥1.0 μg/mL) at the pre-Toddler dose (i.e., prior to the administration of the Toddler dose in the second year of life, between 11–15 months of age). One month after the toddler dose, high levels of anti-PRP titers were achieved in both DTaP-IPV-Hib-HepB recipients (99.8% ≥0.15 μg/mL and 96.6% ≥1.0 μg/mL) and Control (99.5% ≥0.15 μg/mL and 94.9% ≥1.0 μg/mL). CONCLUSION: These results support that DTaP-IPV-Hib-HepB induces an early Hib response in the first 6 months of life that is sustained until the booster dose is administered in the second year of life. Thus, a high percentage of infants vaccinated with DTaP-IPV-Hib-HepB are protected during the high-risk period for Hib disease. [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.