Pneumococcal 21-Valent Conjugate Vaccine in At-Risk Adults: Daily Dose

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On October 18, 2024, we reported on a phase 3 study presented at IDWeek 2024 that assessed the immunogenicity, safety, and tolerability of a 21-valent pneumococcal conjugate vaccine in pneumococcal vaccine-naïve adults aged 18 to 64 years at increased risk of pneumococcal disease (PD).

The study

The STRIDE-8 clinical trial evaluated the immunogenicity, safety, and tolerability of V116 (CAPVAXIVE™, Merck) compared to pneumococcal 15-valent conjugate vaccine (PCV15) in combination with pneumococcal 23-valent polysaccharide vaccine (PPSV23) among 518 vaccine-naïve adults at increased risk of PD, including those with diabetes, cardiovascular disease, kidney disease, liver disease, and lung disease.

Participants were randomly assigned 3:1 to receive a single dose of V116 on day 1 followed by placebo at day 8, or a single dose of PCV15 on day 1 followed by one dose of PPSV23 at week 8. The primary objectives were serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) and immunoglobulin G (IgG) geometric mean concentrations (GMCs) at day 1 and 30-days post-vaccination.

The findings

Results showed that V116 was immunogenic for all 21 serotypes included in the vaccine based on OPA GMTs and IgG GMCs at day 30.

Investigators also observed that the immune responses for V116 were comparable to PCV15 and PPSV23 for the 13 serotypes common to V116 and PCV15 plus PPSV23, and higher responses for the 8 serotypes unique to V116. IgG GMCs were consistent with OPA GMTs.

Authors' comment

“Adults with chronic medical conditions, such as kidney disease or diabetes, are particularly vulnerable to invasive pneumococcal disease, which may increase their risk of severe illness. These data further demonstrate that the broad serotype coverage CAPVAXIVE provides can help prevent invasive disease among vulnerable adults.”

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