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PCV21 vaccine

Phase 3

Pneumococcal Immunization | Monoclonal antibody | Infectious Disease |Sanofi|Last Updated: May 22, 2026

Target and mechanism

ModalityMonoclonal antibody

Also known as PCV21

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindACTIVE_CONTROLLEDDMC
Total Trials5
Total Enrollment7,941

FDA Designations

No designations recorded

Clinical trial landscape

PCV21 vaccine · 5 trials · 2 indications

Phase 3 5
NCT07348692Lot-to-lot Consistency Study of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From 2 Months of AgePneumococcal Immunization
RECRUITING2,195 Analytics
NCT06975878Study of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of AgePneumococcal Immunization
ACTIVE NOT_RECRUITING1,092 Analytics
NCT06824181Study of Mixed Vaccination Schedules With a 21-valent Pneumococcal Conjugate Vaccine and a 20-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of AgePneumococcal Immunization
ACTIVE NOT_RECRUITING580 Analytics
NCT06824194Study of the Safety of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of AgePneumococcal Immunization
ACTIVE NOT_RECRUITING2,360 Analytics
NCT06736041Study of a 4-Dose Regimen of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of AgePneumococcal Immunization
ACTIVE NOT_RECRUITING1,714 Analytics
PHASE3RECRUITING
Lot-to-lot Consistency Study of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From 2 Months of Age
Pneumococcal ImmunizationUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
Study of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of Age
Pneumococcal ImmunizationUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
Study of Mixed Vaccination Schedules With a 21-valent Pneumococcal Conjugate Vaccine and a 20-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of Age
Pneumococcal ImmunizationUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
Study of the Safety of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of Age
Pneumococcal ImmunizationUnlock trial analytics
PHASE3ACTIVE NOT_RECRUITING
Study of a 4-Dose Regimen of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From Approximately 2 Months of Age
Pneumococcal ImmunizationUnlock trial analytics

Study Endpoints

Primary Endpoints

For all participants: Serotype specific Immunoglobulin g (IgG) Geometric Mean Concentration (GMC)
30 days after the third dose of PCV21 vaccine

Serotype specific IgG concentrations for all serotypes included in PCV21 vaccine as measured by electrochemiluminescence assay (ECL)

Seroresponse rate for PCV21 and 15vPCV serotypes
30 days post-toddler dose

Serotype specific IgG concentration ≥ 0.35 µg/mL

IgG concentration for PCV21 and 15vPCV serotypes
30 days post-toddler dose

Serotype specific IgG Geometric Mean Concentration (GMC)

Presence of any immediate adverse events (AEs)
Within 30 minutes after each vaccination

Number of participants experiencing solicited and unsolicited immediate AEs

Presence of solicited injection site and systemic reactions through 7 days after each vaccine injection
Through 7 days after each vaccine injection

Number of participants experiencing solicited injection site and systemic reactions

Presence of unsolicited (spontaneously reported) injection site reactions and unsolicited systemic AEs through 30 days after each vaccine injection
Through 30 days after each vaccine injection

Number of participants experiencing unsolicited injection site reactions and unsolicited systemic AEs

Presence of serious adverse events (SAEs) throughout the study (through 6 months post- last vaccine injection)
Throughout the study (through 6 months post-last vaccine injection), approximately 19 months

Number of participants experiencing SAEs

Presence adverse events of special interest (AESIs) throughout the study (through 6 months post- last vaccine injection)
Throughout the study (through 6 months post-last vaccine injection), approximately 19 months

Number of participants experiencing AESIs

Serotype Specific IgG GMCs for Each Pneumococcal Serotype at 30 Days PD4
30 days PD4

The GMCs for serotype-specific pneumococcal IgG antibodies are measured using electro-chemiluminescence assay (ECL)

Seroresponse rate for PCV21 serotypes
30 days post-dose 3

Serotype specific IgG concentration ≥ 0.35 µg/mL

IgG concentration for PCV21 serotypes
30 days post-dose 3

Serotype specific IgG Geometric Mean Concentration (GMC)

Secondary Endpoints

For all participants: Serotype specific IgG concentration ≥ 0.35 µg/mL
30 days after the third dose of PCV21 vaccine
For all participants: Presence of any immediate adverse events (AEs)
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
Through 7 days after each vaccine injection
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposePREVENTION

Treatment Arms

ArmTypeDescription
Group 1: PCV21EXPERIMENTALParticipants 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.
Group 2: PCV21EXPERIMENTALParticipants 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.
Group 3: PCV21EXPERIMENTALParticipants 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.
Group 4: 20vPCV (Cohort A only)ACTIVE_COMPARATORParticipants will be administered via IM injection 20vPCV at 2, 4, 6 and 12 months of age co-administered with routine pediatric vaccines.
Group 2: 15vPCVACTIVE_COMPARATORParticipants will be administered via intramuscular injection (IM) a 2-dose primary series of 15vPCV at approximately 2 and 4 months of age (MoA) or a 3-dose primary series (preterm infants) at 2, 3, and 4 MoA co- administered with Hexyon. At 11 to 15 MoA, participants will receive a 3rd dose or 4th dose (for preterm infants) of 15vPCV co-administered with Hexyon and M M RvaxPro; Varivax will also be co-administered unless not possible as per local practice
Group 1: 20vPCV-PCV21-PCV21-PCV21EXPERIMENTALParticipants will be administered via intramuscular injection (IM) a 4-dose 20vPCV regimen at approximately 2 MoA, PCV21 at 4 MoA, PCV21 at 6 MoA and PCV21 at 12 to 15 MoA
Group 2: 20vPCV-20vPCV-PCV21-PCV21EXPERIMENTALParticipants will be administered via intramuscular injection (IM) a 4-dose 20vPCV regimen at approximately 2 MoA, 20vPCV at 4 MoA, PCV21 at 6 MoA and PCV21 at 12 to 15 MoA
20vPCV-20vPCV-20vPCV-PCV21EXPERIMENTALParticipants will be administered via intramuscular injection (IM) a 4-dose 20vPCV regimen at approximately 2 MoA, 20vPCV at 4 MoA, 20vPCV at 6 MoA and PCV21 at 12 to 15 MoA
20vPCV-20vPCV-20vPCV-20vPCVACTIVE_COMPARATORParticipants will be administered via intramuscular injection (IM) a 4-dose 20vPCV regimen at approximately 2 MoA, 20vPCV at 4 MoA, 20vPCV at 6 MoA and 20vPCV at 12 to 15 MoA
Group 2: 20vPCVACTIVE_COMPARATORParticipants will be administered via intramuscular injection (IM) a 4-dose 20vPCV regimen at approximately 2, 4, 6 and 12 to 15 MoA

Interventions

NameTypeDescription
PCV21 vaccineBIOLOGICALPharmaceutical form: Suspension for injection Route of administration: Intramuscular
20vPCV licensed vaccineBIOLOGICALPharmaceutical form: Suspension for injection Route of administration: Intramuscular
Vaxneuvance vaccineBIOLOGICALPharmaceutical form:Suspension for injection-Route of administration:Intramuscular
Hexyon vaccineBIOLOGICALPharmaceutical form:Suspension for injection-Route of administration:Intramuscular
M-M-RvaxPro vaccineBIOLOGICALPharmaceutical form:Powder and solvent for suspension for injection-Route of administration:Intramuscular or Subcutaneous
Varivax vaccineBIOLOGICALPharmaceutical form:Powder and solvent for suspension for injection-Route of administration:Intramuscular or Subcutaneous
Prevnar 20 vaccineBIOLOGICALPharmaceutical form:Suspension for injection-Route of administration:Intramuscular
M-M-R II vaccineBIOLOGICALPharmaceutical form:Powder, lyophilized, for suspension for reconstitution-Route of administration:Subcutaneous or Intramuscular
RotarixBIOLOGICALPharmaceutical form:Solution-Route of administration:Oral
RotaTeqBIOLOGICALPharmaceutical form:Solution-Route of administration:Oral
Vaxelis vaccineBIOLOGICALPharmaceutical form:Suspension for injection-Route of administration:Intramuscular
VarivaxBIOLOGICALPharmaceutical form:Powder, lyophilized, for suspension for reconstitution-Route of administration:Subcutaneous or Intramuscular
PriorixBIOLOGICALPharmaceutical form:Lyophilized, for suspension for reconstitution-Route of administration:Subcutaneous
VAQTABIOLOGICALPharmaceutical form:Suspension for Injection-Route of administration:Intramuscular
HavrixBIOLOGICALPharmaceutical form:Suspension for Injection-Route of administration:Intramuscular
Hexaxim VaccineBIOLOGICALPharmaceutical form:Suspension for injection-Route of administration:Intramuscular
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Eligibility Criteria

Age Range42 Days to 89 Days
SexALL
Healthy VolunteersYes
Study Sites19

Inclusion Criteria: * Aged 42 to 89 days on the day of inclusion * Participants who are healthy as determined by medical evaluation including medical history and physical examination * Born at full term of pregnancy (≥ 37 weeks) and with a birth weight ≥ 2.5 kg or born after a gestation period abov...

Countries:United StatesHondurasPuerto RicoBelgiumCzechiaEstoniaFinlandGermanyGreeceItalyPolandChileMexicoPhilippinesThailandTurkey (Türkiye)AustraliaSouth Korea
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Frequently asked questions about PCV21 vaccine

What is PCV21 used for?

PCV21 is an investigational 21-valent pneumococcal conjugate vaccine being developed for pneumococcal immunization and the prevention of pneumococcal infections. It is also being studied in children and adolescents with sickle cell disease, a population at increased risk for pneumococcal disease.

Who makes PCV21?

PCV21 is being developed by Sanofi, a global biopharmaceutical company traded on the stock exchange under the ticker symbol SNY. The vaccine is currently in Phase 3 clinical development for pneumococcal immunization and related indications.

What phase is PCV21 in?

PCV21 is in Phase 3 clinical development. It is an investigational vaccine and has not been approved by regulatory authorities. All five of its clinical trials are active, with four currently recruiting or active but not recruiting participants across multiple countries.

What clinical trials is PCV21 in?

PCV21 is being evaluated in five Phase 3 trials, including NCT06824194 in healthy infants, NCT06838000 as catch-up vaccination in infants through adolescents, NCT06975878 in healthy infants, and NCT07247188 in children with sickle cell disease. These trials are enrolling participants in the United States, Europe, and other regions.

Is PCV21 the same as PCV21 vaccine?

Yes, PCV21 is also known as PCV21 vaccine. Both names refer to the same investigational 21-valent pneumococcal conjugate vaccine being developed by Sanofi for the prevention of pneumococcal infections and immunization.

How does PCV21 work?

PCV21 is a pneumococcal conjugate vaccine designed to elicit an immune response against 21 serotypes of Streptococcus pneumoniae bacteria. By presenting these bacterial components to the immune system, the vaccine aims to generate protective antibodies that can prevent pneumococcal infections.