Single Dose of PCV20 for Toddlers Following Previous PCV13 Doses Protects Against Additional Pneumococcal Serotypes

A single toddler dose of 20-valent pneumococcal conjugate vaccine (PCV20, Prevnar 20; Pfizer) following 2 previous infant doses of 13-valent PCV (PCV13) was found to have elicited immune responses expected to provide protection against pneumococcal disease caused by all 20 vaccine serotypes, with a similar tolerability and safety profile to PCV13, according to results from a phase 3, randomized, partially double-blind trial (NCT05408429) published in Vaccine.^1,2

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The Advisory Committee on Immunization Practices (ACIP) approved in 2023 recommendations for the use of PCV20 in US children, with these recommendations adopted by the CDC. Prior to this recommendation, the FDA approved an expanded use of PCV20 to include persons aged 6 weeks to 17 years. ACIP recommended the use of PCV20 in persons who had previously received pneumococcal vaccines, expanding options for pediatric patients with a vaccine that covers more pneumococcal serotypes (8, 10A, 11A, 12F, 15B, 22F, and 33F) associated with disease severity and invasive potential in pediatrics.^1,3,4

Given the multiple options for pediatric pneumococcal protection, it is critical to elucidate the safety and effectiveness of different pneumococcal vaccines at different pediatric stages. Previous literature has investigated PCV20 given as 2 or 3 infant doses plus a toddler dose in healthy infants. Two randomized phase 3 trials found that this regimen elicited robust immunoglobulin G (IgG) responses, in addition to functional immune responses against all 20 vaccine serotypes. In this current investigation, the authors sought to determine the immunogenicity, safety, and tolerability of 1 or 2 doses of PCV20 administered to toddlers who had previously received 2 doses of PCV13 in their infancy.¹

Enrolled participants—including healthy toddlers 12 or more to less than 24 months of age with documented receipt of 2 PCV13 doses during infancy—were randomized 1:1:1 to receive either 1 or 2 doses of PCV20 or 1 dose of PCV13. Conducted in the European Union, where the 3-dose series of PCV13 was recommended at the time of study initiation, 356 total patients were randomized (2-dose PCV20 group, n = 121; 1-dose PCV20 group, n = 118; PCV13 control group, n = 117) and immunized at sites in Hungary, Poland, and Spain.¹

Immunogenicity was reviewed first. Following 1 dose of PCV20, 75.9% of participants had IgG concentrations that met or exceeded the predefined level for all 7 additional serotypes, except serotype 12F. Continuing, after 2 doses of PCV20, the percentage of patients with IgG concentrations meeting or exceeding predefined levels for the 7 additional serotypes ranged from 91.2% to 100.0%, according to the investigators. For the 13 matched serotypes, the percentages of patients with predefined IgG thresholds were generally similar across all 3 groups, ranging from 87.9% to 100.0% in the 1-dose PCV20 group, 88.2% to 100.0% in the 2-dose PCV20 group, and 93.5% to 100.0% in the PCV13 group.¹

Regarding the regimen’s safety profile, the investigators reported that most local reactions and systemic events were mild or moderate in severity, with the percentages of patients with local reactions being similar in the 2-dose PCV20, 1-dose PCV20, and PCV13 groups. Accordingly, the percentages of participants with systemic events following their final vaccine dose were similar across all 3 vaccine groups. In an important observation, there were no adverse events considered to be vaccine-related during the study, according to the investigators.¹

“A single toddler dose of PCV20 after 2 previous infant PCV13 doses elicited immune responses that are expected to provide protection against the 7 additional serotypes,” the study authors concluded. “The immune responses after a single toddler dose of PCV20 are also expected to provide similar protection against the 13 matched serotypes as for PCV13, supporting a transition from PCV13 to PCV20 at the toddler dose in a 2 + 1 series.”¹

REFERENCES

1. Martinón-Torres F, Martinez SN, Kline MJ, et al. A phase 3 study of 20-valent pneumococcal conjugate vaccine in healthy toddlers previously vaccinated in infancy with 13-valent pneumococcal conjugate vaccine. Vaccine. 2025;53(19):126931. doi:10.1016/j.vaccine.2025.126931

2. ClinicalTrials.gov. Safety and Immunogenicity of 20vPnC in Toddlers With 2 Prior Doses of Prevenar 13. National Library of Medicine. Last Updated September 19, 2024. Accessed April 2, 2025. https://clinicaltrials.gov/study/NCT05408429

3. ACIP Updates: Recommendations for Use of 20-Valent Pneumococcal Conjugate Vaccine in Children ― United States, 2023. MMWR Morb Mortal Wkly Rep. 2023;72:1072. doi:10.15585/mmwr.mm7239a5.

4. McKeirnan KC. 2023 ACIP updates for immunizations in adults and children: What pharmacists need to know. Pharmacy Times. Published June 13, 2023. Accessed April 2, 2025. https://www.pharmacytimes.com/view/2023-acip-updates-for-immunizations-in-adults-and-children-what-pharmacists-need-to-know