The V114-008 trial compared the safety, tolerability, and immunogenicity of V114 to the existing 13-valent pneumococcal conjugate vaccine (PCV13) in healthy infants aged six to 12 weeks.
The trial met the primary endpoint of non-inferiority of V114 across the serotypes in both vaccines.
In addition, the investigational vaccine induced an immune response for 22F and 33F, the two additional disease-causing serotypes not present in PCV13.
V114 is being developed to prevent pneumococcal disease in both adults and children.
The randomised, double-blind Phase II study evaluated two clinical lots of V114 in a total of 1,050 healthy infants aged two, four, six and 12-15 months.
Results showed that the proportion of participants experiencing the WHO-accepted threshold of immune response with either V114 lot was not inferior to the percentage in case of PCV13 for the 13 serotypes shared between the vaccines.
The adverse event profile for V114 observed during the trial was comparable to that of PCV13.
Merck Research Laboratories vaccine and infectious diseases clinical research senior vice-president and head Dr Nicholas Kartsonis said: “These new data for our investigational pneumococcal disease vaccine V114 build on Merck’s century-long heritage in vaccines and our commitment to improving global health through protection from infectious diseases.
“We are deeply committed to advancing compounds such as V114 that have the potential to make a meaningful impact on the burden of pneumococcal disease.”
In January this year, V114 secured the US Food and Drug Administration (FDA) breakthrough therapy designation to prevent invasive pneumococcal disease (IPD) by the vaccine serotypes in paediatric patients six weeks to 18 years of age.
The approval was partly based on immunogenicity data from this Phase II trial and the Phase I/II V114-005 study in healthy adults and infants.
Merck is further studying the vaccine in a Phase III clinical development programme comprising 11 trials.