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Novel 21-Valent Pneumococcal Conjugate Vaccine for Adults Shows Positive Data in Phase III Trial

Image credit: Jezper |

Data from the Phase III STRIDE-10 trial show the promise of Merck’s novel 21-valent pneumococcal conjugate vaccine V116 to prevent invasive pneumococcal disease and pneumonia in adults aged 50 years and older who had not previously received a pneumococcal vaccine.1 V116 includes eight serotypes that are not currently approved by pneumococcal vaccines, including 15A, 15C, 16F, 23A, 23B, 24F, 31, and 35B.

“Even with the availability of current pneumococcal conjugate vaccines for adults, gaps in serotype coverage for invasive pneumococcal disease persist,” Eliav Barr, MD, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories, said in a press release. “These data add to the evidence supporting the potential for V116 to become an important new preventative option for adults, with results showing V116 elicited immune responses to the serotypes responsible for the majority of adult invasive pneumococcal disease.”1

With over 100 different serotypes of pneumococcal bacteria, the condition may affect adults differently than children.1 Individuals with an elevated risk of infection include older adults and patients with certain chronic or immunocompromising health conditions, such as heart disease, lung disease, and liver disease. Mortality from invasive pneumococcal disease is highest among those aged 50 years and older.2

The eight serotypes in V116 that are not addressed by current pneumococcal vaccines are responsible for approximately 30% of invasive pneumococcal disease in those aged 65 years and older. Pre-pandemic 2019 data from the CDC indicate that the 21 serotypes covered by the V116 vaccine are responsible for 85% of invasive pneumococcal disease in adults 65 years of age and older.2 The randomized, double-blind, active comparator-controlled STRIDE-10 trial evaluated the safety, tolerability, and immunogenicity of V116 compared with PPSV23 in individuals aged 18 years older (n=1,484), who were randomly assigned to receive a single dose of either vaccine.

The trial’s primary objectives included serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) at 30 days post-vaccination and the percentage of individuals showing greater than or equal to a four-fold rise from baseline in serotype-specific OPAs, the responses of which were evaluated at baseline and 30 days post-vaccination.

Investigators observed noninferior immune responses in patients administered V116 compared to PPSV23 across the 12 serotypes common for both vaccines, measured by serotype-specific OPA GMTs at day 30. For the nine serotypes in V116 but not PPSV23, the novel vaccine demonstrated superiority as measured by OPA GMT ratios at day 30, as well superiority for eight of the nine serotypes unique to V116 measured by the proportions of individuals showing ≥four-fold increases in immune responses.

In terms of safety, V116 showed a profile comparable to PPSV23. There were no serious vaccine-related adverse events or vaccine-related deaths in the study.3

“Invasive pneumococcal disease and pneumococcal pneumonia represent significant public health challenges, particularly among older adult populations and those with risk conditions,” Walter Orenstein, MD, professor emeritus of medicine, epidemiology, global health and pediatrics at Emory University and member of Merck’s Scientific Advisory Committee, said in a press release. “These positive results show that V116 has the potential to help prevent invasive pneumococcal disease among adult populations.”


1. Merck Announces Positive Data for V116, an Investigational, 21-Valent Pneumococcal Conjugate Vaccine Specifically Designed for Adults. News release. Merck. April 29, 2024. Accessed April 30, 2024.

2. FDA Grants Priority Review to Merck’s New Biologics License Application for V116, an Investigational, 21-valent Pneumococcal Conjugate Vaccine Specifically Designed to Protect Adults. Merck. News release. December 19, 2023. Accessed April 30, 2024.

3. Merck announces V116, an investigational, 21-valent pneumococcal conjugate vaccine specifically designed for adults, met key immunogenicity and safety endpoints in two phase 3 trials. Merck. News release. July 27, 2023. Accessed April 30, 2024.