Study of an Investigational Pneumococcal Vaccine at Three Dose Levels in Healthy Adults

• Aged 18 to 50 years on the day of inclusion
• Informed consent form has been signed and dated
• Able to attend all scheduled visits and comply with all trial procedures
• Subject is healthy, as determined by medical history and physical examination
• For a woman of child-bearing potential, use of an effective method of contraception or abstinence from at least 4 weeks prior to first vaccination until 4 weeks after the last vaccination.

Exclusion Criteria:

• History of anaphylactic reaction or asthma
• Unknown pregnancy or positive serum/urine pregnancy test
• Currently breastfeeding a child
• Chronic illness, that in the opinion of the investigator, is at a stage that could interfere with trial conduct or completion
• Participation in another clinical trial investigating a vaccine, drug, medical device, or a medical procedure in the 4 weeks preceding the first trial vaccination
• Planned participation in another clinical trial during the present trial period
• Known or suspected congenital or acquired immunodeficiency, receipt of immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
• Known systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to the trial vaccine or to a vaccine containing any of the same substances
• Current alcohol abuse or drug addiction that may interfere with the subject's ability to comply with trial procedures
• Receipt of blood or blood-derived products in the past 3 months, that might interfere with the assessment of immune response
• Receipt of any vaccine in the 4 weeks preceding the first trial vaccination, except for pandemic influenza vaccination which may be received at least two weeks before the study vaccines
• Planned receipt of any vaccine in the 4 weeks following the trial vaccination, except for pandemic influenza vaccination in the event of a local or national immunization program
• Known seropositivity for Human Immunodeficiency Virus (HIV), Hepatitis B, or Hepatitis C
• Laboratory confirmed/self-reported thrombocytopenia contraindicating intramuscular (IM) vaccination
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
• Identified as a study site employee who is involved in the protocol and may have direct access to trial-related data
• Previous vaccination against pneumococcal disease (in the previous 5 years)
• History of pneumococcal infection (confirmed either clinically, serologically, or microbiologically) within 5 years
• At high risk for pneumococcal infection during the trial
• Living in a household with children \<5 years of age.