Phase 3 Safety and Immunogenicity Study of a Three-dose Series of Twenty-valent Pneumococcal Conjugate Vaccine in Healthy Infants and Toddlers.

BACKGROUND: Global pediatric immunization programs with pneumococcal conjugate vaccines (PCVs) have reduced vaccine-type pneumococcal disease, but a substantial disease burden of non-PCV serotypes remains. METHODS: This phase 3, randomized (1:1), double-blind study evaluated safety and immunogenicity of 20-valent PCV (PCV20) relative to 13-valent PCV (PCV13) in healthy infants. Participants received 2 infant doses and a toddler dose of PCV20 or PCV13, with diphtheria-tetanus-acellular pertussis combination vaccine at all doses and measles, mumps, rubella and varicella vaccines at the toddler dose. Primary pneumococcal immunogenicity objectives were to demonstrate noninferiority (NI) of PCV20 to PCV13 for immunoglobulin G geometric mean concentrations after infant and toddler doses and percentages of participants with predefined serotype-specific immunoglobulin G concentrations after infant doses. Safety endpoints included local reactions, systemic events and adverse events. RESULTS: Overall, 1204 participants were vaccinated (PCV20, n = 601; PCV13, n = 603). One month after the toddler dose, 19/20 serotypes met NI for immunoglobulin G geometric mean concentrations; serotype 6B narrowly missed NI [PCV20/PCV13 geometric mean ratio: 0.57 (2-sided 95% confidence interval: 0.48-0.67); NI criterion: lower 2-sided 95% confidence interval >0.5]. Sixteen/twenty serotypes met NI for ≥1 primary objective after 2 infant doses. PCV20 induced robust opsonophagocytic activity, and boosting responses were observed for all vaccine serotypes, including those missing statistical NI. The safety/tolerability profile of PCV20 was like that of PCV13. CONCLUSIONS: PCV20 3-dose series in infants was safe and elicited robust immune responses. Based on these results and PCV13 experience, PCV20 3-dose series is expected to be protective for all 20 vaccine serotypes. NCT04546425.

Safety and Immunogenicity of a 20-valent Pneumococcal Conjugate Vaccine in Healthy Infants in the United States.

BACKGROUND: The development and widespread use of pneumococcal conjugate vaccines (PCVs) substantially reduced the global burden of pneumococcal disease. Expanding the serotypes covered by PCVs may further reduce disease burden. A 20-valent PCV (PCV20) has been developed to add coverage for 7 additional serotypes (8, 10A, 11A, 12F, 15B, 22F and 33F) to those in the existing 13-valent PCV (PCV13). This phase 2 study evaluated the safety, tolerability and immunogenicity of PCV20 in healthy US infants. METHODS: In this randomized, active-controlled, double-blind study, 460 infants were randomized 1:1 to receive a 4-dose series of either PCV20 or PCV13 at 2, 4, 6 and 12 months of age. Solicited local reactions and systemic events, adverse events (AEs) and serious AEs were recorded. Immunogenicity was assessed by measuring serotype-specific IgG concentrations and opsonophagocytic activity titers at 1 month after Dose 3, before Dose 4 and 1 month after Dose 4. RESULTS: Of 460 infants, 82.8% completed the 1-month visit after Dose 4. Local reactions and systemic events were mostly mild to moderate in severity and similar between the PCV20 and PCV13 groups. Treatment-related AEs were uncommon, with no related serious AEs or deaths reported. IgG and opsonophagocytic activity responses elicited by PCV20 were robust and demonstrated a booster response after Dose 4. CONCLUSIONS: Administration of PCV20 in US infants was well tolerated, with a safety profile similar to PCV13, and induced robust serotype-specific immune responses. These findings support continued development of PCV20 in the pediatric population.