A Phase 3 interventional study of PCV21 vaccine and 20vPCV licensed vaccine in Pneumococcal Immunization and Healthy Volunteers, sponsored by Sanofi. Recruiting at 25 sites in 4 countries. Open to participants aged 42 Days to 89 Days, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-05.
Sponsored by Sanofi · Phase 3, Interventional, and Prevention
This is a phase 3 randomized, modified double-blind study whose purpose is to measure whether 3 lots of the investigational pneumococcal vaccine PCV21 can help the body to develop germ-fighting agents called "antibodies" (immunogenicity) in a similar way (ie, same immune response) when they are given to infants aged from approximately 2 months (42 to 89 days) and are safe compared to a licensed 20-valent pneumococcal vaccine (20vPCV) (Prevnar 20™).
The study duration per participant will be up to approximately 17 months. The study vaccines (either PCV21 or 20vPCV) will be administered at approximately 2, 4, 6 and 12 months of age. Cohort A will include randomization to three PCV21 formulation groups or one 20vPCV comparator group (Group 1-4, approximately 896 total participants), whereas Cohort B will include randomization to three PCV21 formulation groups only (Groups 1-3, approximately 1299 total participants). Routine pediatric vaccines will be given as per local recommendations.
There will be 6 study visits: Visit (V)01, V02 separated from V01 by 60 days, V03 separated from V02 by 60 days, V04 separated from V03 by 30 days, V05 at 12 months of age, V06 separated from V05 by 30 days
298 studies on the registry are indexed under Pneumococcal Infections; 26 are open to participants now.
This study's planned enrollment of 2,195 is above the median of 373 across 253 interventional studies indexed under Pneumococcal Infections.
Browse Pneumococcal Infections studies →Sanofi is the lead sponsor of 1,557 studies on the registry; 91 are open to participants now.
Of its 205 completed or terminated interventional studies of FDA-regulated products, 123 (60%) 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:
Note: The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.
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 weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will be administered via intramuscular injection (IM) PCV21 vaccine lot 1 for Doses 1, 2 and 3; PCV21 lot 1, or different lot if needed, for Dose 4 at 2, 4, 6 and 12 months of age co-administered with routine pediatric vaccines.
Biological: PCV21 vaccine
Participants will be administered via IM injection PCV21 vaccine lot 2 for Doses 1, 2 and 3; PCV21 lot 2, or different lot if needed, for Dose 4 at 2, 4, 6 and 12 months of age co-administered with routine pediatric vaccines.
Biological: PCV21 vaccine
Participants will be administered via IM injection PCV21 vaccine lot 3 for Doses 1, 2 and 3; PCV21 lot 3, or different lot if needed, for Dose 4 at 2, 4, 6 and 12 months of age co-administered with routine pediatric vaccines.
Biological: PCV21 vaccine
Participants will be administered via IM injection 20vPCV at 2, 4, 6 and 12 months of age co-administered with routine pediatric vaccines.
Biological: 20vPCV licensed vaccine
Pharmaceutical form: Suspension for injection Route of administration: Intramuscular
Also known as: 515
Pharmaceutical form: Suspension for injection Route of administration: Intramuscular
Also known as: Prevnar 20™
For all participants: Serotype specific Immunoglobulin g (IgG) Geometric Mean Concentration (GMC)
Serotype specific IgG concentrations for all serotypes included in PCV21 vaccine as measured by electrochemiluminescence assay (ECL)
Time frame: 30 days after the third dose of PCV21 vaccine
For all participants: Serotype specific IgG concentration ≥ 0.35 µg/mL
Serotype specific IgG concentration ≥ 0.35 μg/mL (seroresponse) for all serotypes included in PCV21 as measured by ECL
Time frame: 30 days after the third dose of PCV21 vaccine
For all participants: Presence of any immediate adverse events (AEs)
Number of participants experiencing immediate AEs
Time frame: Within 30 minutes after each vaccine injection
For participants in Cohort A (reactogenicity subset): Presence of solicited injection site and systemic reactions through 7 days after each vaccine injection
Number of participants experiencing solicited injection site and systemic reactions
Time frame: Through 7 days after each vaccine injection
For all participants: Presence of unsolicited (spontaneously reported) injection site reactions and unsolicited systemic AEs
Number of participants experiencing unsolicited injection site reactions and unsolicited systemic AEs
Time frame: Through 30 days after each vaccine injection
For all participants: Presence of serious adverse events (SAEs) and adverse events of special interest (AESIs) throughout the study
Number of participants experiencing SAEs and AESIs
Time frame: Throughout the study (through 6 months post-last vaccine injection)
Plan to share: Yes — Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org
No publications or documents are linked to this record.
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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Studies of the drug tested here: Pneumococcal 21-Valent Conjugate Vaccine