A Phase 3 interventional study of PG4 and 20-valent pneumococcal conjugate vaccine (20vPnC) in Pneumococcal Disease, sponsored by Pfizer. Recruiting at 130 sites in 3 countries. Open to participants aged 42 Days to 211 Days, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Pfizer · Phase 3, Interventional, and Prevention
The purpose of this study is to learn about the safety of a new pneumococcal vaccine and how the new pneumococcal vaccine helps to fight against germs that can cause pneumonia (lung infections), meningitis (brain infections), and otitis media (ear infections) in infants when compared to the pneumococcal vaccine that is currently in use, 20vPnC (Prevnar 20®).
This study will test if the new pneumococcal vaccine is as safe as the one that is currently in use. It will also assess how the new vaccine works in comparison to the one that is currently in use when given with other childhood vaccines.
To measure how the new pneumococcal vaccine compares to the current one, blood samples will be used to measure the body's ability to create proteins to fight those germs. This new vaccine can possibly provide additional protection against germs that cause pneumococcal disease that are not included in the vaccines that are currently given to infants. Pneumococcal disease includes a variety of infections caused by a specific germ, Streptococcus pneumoniae.
There are three groups in this study. All participants will be assigned to one of the three groups. This study is seeking participants who are:
About 3000 infants will be assigned to Group 1. The infants in this group will have a 1 in 2 chance (50%) of receiving either PG4 (new vaccine) or 20vPnC (currently in use) into the left thigh muscle at 2, 4, 6, and 12 to 15 months of age.
About 140 infants from outside the United States will be assigned to Group 2. The infants in this group will have a 1 in 2 chance (50%) of receiving either PG4 or 20vPnC into the left thigh muscle at 2 to 6, 3 to 8, 4 to 10, and 12 to 15 months of age.
About 90 infants from outside the United States will be assigned to Group 3. The infants in Group 3 will have a 1 in 3 chance (33%) of receiving either PG4 into the left thigh muscle, PG4 under the skin of the left thigh, or 20vPnC into the left thigh muscle at 2 to 6, 3 to 8, 4 to 10, and 12 to 15 months of age.
Infants in Group 1 will take part in this study for about 16 to 19 months (about 1 and a half years). Infants in Groups 2 and 3 will take part in this study for 12 to 21 months (about 1 to 1 and a half years). During this time, infants will have 6 study clinic visits and 1 phone call. At these study clinic visits, parent(s)/legal guardian(s) will be asked if the infant experienced any side effects. A side effect is an unintentional or unexpected reaction to a vaccine. Infants will have 3 blood samples collected.
298 studies on the registry are indexed under Pneumococcal Infections; 26 are open to participants now.
This study's planned enrollment of 3,230 is above the median of 373 across 253 interventional studies indexed under Pneumococcal Infections.
Browse Pneumococcal Infections studies →Pfizer is the lead sponsor of 3,334 studies on the registry; 149 are open to participants now.
Of its 601 completed or terminated interventional studies of FDA-regulated products, 391 (65%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Multivalent Pneumococcal Vaccine
Biological: PG4
20-valent pneumococcal conjugate vaccine (20vPnC)
Biological: 20-valent pneumococcal conjugate vaccine (20vPnC)
Multivalent Pneumococcal Vaccine
Biological: PG4
20-valent pneumococcal conjugate vaccine (20vPnC)
Biological: 20-valent pneumococcal conjugate vaccine (20vPnC)
Multivalent Pneumococcal Vaccine
Biological: PG4
Multivalent Pneumococcal Vaccine
Biological: PG4
20-valent pneumococcal conjugate vaccine (20vPnC)
Biological: 20-valent pneumococcal conjugate vaccine (20vPnC)
Multivalent Pneumococcal Vaccine
20-valent pneumococcal conjugate vaccine (20vPnC)
Also known as: Prevnar 20
Percentage of participants reporting local reactions within 7 days after each dose
Prompted local reactions after each dose
Time frame: Day 7
Percentage of participants reporting systemic events within 7 days after each dose
Prompted systemic events after each dose
Time frame: Day 7
Percentage of participants reporting adverse events (AEs) from Dose 1 to 1 month after Dose 3
AEs occurring from Dose 1 to 1 month after Dose 3
Time frame: Dose 1 to 1 month after Dose 3
Percentage of participants reporting AEs from Dose 4 to 1 month after Dose 4
AEs occurring from Dose 4 to 1 month after Dose 4
Time frame: Dose 4 to 1 month after Dose 4
Percentage of participants reporting serious adverse events (SAEs)
SAEs occurring from Dose 1 to 6 months after Dose 4
Time frame: Dose 1 to 6 months after Dose 4
Differences in percentages of participants with predefined pneumococcal specific immunoglobulin G (IgG) concentrations 1 month after Dose 3
Differences in pneumococcal immunoglobulin G (IgG) concentrations 1 month after Dose 3
Time frame: 1 month after Dose 3
Pneumococcal IgG geometric mean concentrations (GMCs) 1 month after Dose 4
Pneumococcal IgG GMCs 1 month after Dose 4
Time frame: 1 month after Dose 4
Pneumococcal IgG GMCs 1 month after Dose 3
Pneumococcal IgG GMCs 1 month after Dose 3
Time frame: 1 month after Dose 3
Percentage of participants with serotype 3 specific predefined pneumococcal IgG concentrations 1 month after Dose 3
Pneumococcal serotype 3 IgG concentrations 1 month after Dose 3
Time frame: 1 month after Dose 3
Pneumococcal serotype 3 IgG GMCs 1 month after Dose 4
Pneumococcal serotype 3 IgG GMCs 1 month after Dose 4
Time frame: 1 month after Dose 4
Differences in percentages of participants with predefined pneumococcal serotype 6C and 15C immunoglobulin G (IgG) concentrations 1 month after Dose 3
Differences in pneumococcal serotype 6C and 15C immunoglobulin G (IgG) concentrations 1 month after Dose 3
Time frame: 1 month after Dose 3
Pneumococcal serotype 6C and 15C IgG GMCs and GMRs 1 month after Dose 4
Pneumococcal serotype 6C and 15C IgG GMCs and GMRs 1 month after Dose 4
Time frame: 1 month after Dose 4
Pneumococcal opsonophagocytic activity (OPA) titers 1 month after Dose 3
Pneumococcal OPA titers 1 month after Dose 3
Time frame: 1 month after Dose 3
Pneumococcal OPA titers prior to Dose 4
Pneumococcal OPA titers prior to Dose 4
Time frame: Prior to Dose 4
Pneumococcal OPA titers 1 month after Dose 4
Pneumococcal OPA titers 1 month after Dose 4
Time frame: 1 month after Dose 4
Percentage of participants with predefined pneumococcal specific IgG concentrations 1 month after Dose 4
Percentage of participants with predefined pneumococcal specific IgG concentrations 1 month after Dose 4
Time frame: 1 month after Dose 4
Pneumococcal IgG concentrations 1 month after Dose 3
Pneumococcal IgG concentrations 1 month after Dose 3
Time frame: 1 month after Dose 3
Pneumococcal IgG concentrations prior to Dose 4
Pneumococcal IgG concentrations prior to Dose 4
Time frame: Prior to Dose 4
Pneumococcal IgG concentrations 1 month after Dose 4
Pneumococcal IgG concentrations 1 month after Dose 4
Time frame: 1 month after Dose 4
IgG geometric mean fold rise (GMFR) from before Dose 4 to 1 month after Dose 4
IgG GMFR from before Dose 4 to 1 month after Dose 4
Time frame: Before Dose 4 to 1 month after Dose 4
IgG GMFR from 1 month after Dose 3 to 1 month after Dose 4
IgG GMFR from 1 month after Dose 3 to 1 month after Dose 4
Time frame: From 1 month after Dose 3 to 1 month after Dose 4
Percentages of participants with prespecified antibody levels to specific concomitant vaccine antigens 1 month after Dose 3
Prespecified antibody levels to specific concomitant vaccine antigens 1 month after Dose 3
Time frame: 1 month after Dose 3
Geometric mean of antibody levels to measles, mumps, rubella, varicella, and hepatitis A virus antigens 1 month after Dose 4
Geometric mean of antibody levels to measles, mumps, rubella, varicella, and hepatitis A virus antigens 1 month after Dose 4
Time frame: 1 month after Dose 4
Geometric mean of immunoglobulin A (IgA) antibody levels to rotavirus 1 month after Dose 3
Geometric mean of IgA antibody levels to rotavirus 1 month after Dose 3
Time frame: 1 month after Dose 3
Showing the first 100 of 130 sites across 3 countries. Choose a country and city above to see the rest.
Plan to share: Yes — Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.
Data sharing details ↗ · www.pfizer.com
Started May 2026 (actual). Primary completion is estimated for Jun 2029, 36 months after the start.
Of 81 industry-sponsored phase 3 interventional studies under Pneumococcal Infections, half reached primary completion within 13 months of starting (the median), counting those still running; a quarter within 9 and three quarters within 23. This study's planned 36 months is above that.
Counting every sponsor, half of 82 studies reached it within 13 months; a quarter within 9 and three quarters within 23.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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