Vaccine · California
Vaccine studies in California
36 studies have at least one recruiting site in California. Vaccine trials test how well new or updated vaccines produce an immune response and how they are tolerated. Many recruit healthy adults; some focus on older adults, children or people with specific conditions.
36 recruiting studiesSource: ClinicalTrials.gov, refreshed October 26, 2026How we list studies
Studies
- RecruitingHealthy volunteersPhase 1/Phase 2
A Study of BLB-201 RSV Vaccine in Infants and Children
Blue Lake Biotechnology Inc.
- Location
- La Mesa, CA + 13 other US sites
- Eligibility basics
- Ages 6 mo–5
- RecruitingHealthy volunteersPhase 1/Phase 2
Phase 1/2 Study of Respiratory Syncytial Virus and Human Metapneumovirus (RSV+HMPV) Vaccine Candidate in Adults 60 Years of Age and Older
Sanofi
- Location
- Huntington Beach, CA + 49 other US sites
- Eligibility basics
- Ages 60+
- RecruitingHealthy volunteersPhase 1
A Clinical Study of Novel Pneumococcal Vaccine V118C in Children (V118C-002)
Merck Sharp & Dohme LLC
- Location
- Madera, CA + 14 other US sites
- Eligibility basics
- Ages 2 mo–1
- RecruitingHealthy volunteersPhase 1/Phase 2
Study to Assess Safety and Immunogenicity of an Egg-based H5N8 Influenza Vaccine at Multiple Dose Levels Adjuvanted With Matrix-M in Healthy Participants 18 Years of Age and Above.
Sanofi
- Location
- Rolling Hills Estates, CA + 15 other US sites
- Eligibility basics
- Ages 18+
- RecruitingHealthy volunteersPhase 1
A Study to Learn About a Vaccine Against E Coli in Healthy Adults
Pfizer
- Location
- Anaheim, CA + 9 other US sites
- Eligibility basics
- Ages 18–64
- RecruitingHealthy volunteersPhase 1
A Vaccine (CMV-MVA Triplex Vaccine) for the Enhancement of CMV-Specific Immunity and the Prevention of CMV Viremia in Patients Undergoing Haploidentical Hematopoietic Stem Cell Transplant
City of Hope Medical Center
- Location
- Duarte, CA + 2 other US sites
- Eligibility basics
- Ages 18–75
- RecruitingHealthy volunteersPhase 1/Phase 2
A Phase 1/2A, Randomized Study of a T Follicular Helper (TFH)-Targeting Genetic Vaccine Strategy Designed to Induce Broad, Durable Immune Responses
Kara Chew
- Location
- Los Angeles, CA + 1 other US site
- Eligibility basics
- Ages 40–64
- RecruitingHealthy volunteersPhase 3
A Study to Learn About How a New Pneumococcal Vaccine Works in Infants.
Pfizer
- Location
- Anaheim, CA + 101 other US sites
- Eligibility basics
- Ages 1 mo–7 mo
- RecruitingHealthy volunteersPhase 4
Study of a Recombinant Spike COVID-19 Vaccine With Matrix-M in Older Adults and People at Increased Risk of Severe COVID-19
Sanofi
- Location
- Fair Oaks, CA + 19 other US sites
- Eligibility basics
- Ages 12+
- RecruitingHealthy volunteersPhase 3
A Phase 3 Study of Revaccination in Subsequent Pregnancies With Bivalent RSV Vaccine and Duration of Protection of a Single Dose
Pfizer
- Location
- Los Angeles, CA + 76 other US sites
- Eligibility basics
- Ages 0 mo+
- RecruitingHealthy volunteersPhase 3
A Study to Assess the Safety, Tolerability, and Immunogenicity of 3 Lots of a Multivalent Pneumococcal Conjugate Vaccine Administered to Adults
Pfizer
- Location
- Lake Forest, CA + 36 other US sites
- Eligibility basics
- Ages 18–49
- RecruitingHealthy volunteersPhase 3
A Study to Learn About a Clostridioides Difficile Vaccine in People 65 Years of Age and Older
Pfizer
- Location
- Daly City, CA + 138 other US sites
- Eligibility basics
- Ages 65+
- RecruitingHealthy volunteersPhase 3
A Study to Evaluate the Immune Response and Safety of a Vaccine Against Influenza in Adults 18-64 Years of Age
GlaxoSmithKline
- Location
- San Diego, CA + 11 other US sites
- Eligibility basics
- Ages 18–64
- RecruitingHealthy volunteersPhase 3
Lot-to-lot Consistency Study of a 21-valent Pneumococcal Conjugate Vaccine in Healthy Infants From 2 Months of Age
Sanofi
- Location
- Huntington Park, CA + 13 other US sites
- Eligibility basics
- Ages 1 mo–2 mo
- RecruitingHealthy volunteersPhase 3
BEATRIX: A Study to Learn About a Group B Streptococcus Vaccine in Healthy Pregnant Women and Their Babies
Pfizer
- Location
- Lancaster, CA + 111 other US sites
- Eligibility basics
- Ages 0 mo–49
- RecruitingHealthy volunteersPhase 3
A Study on the Efficacy of a Vaccine Against Influenza in Adults ≥65 Years of Age
GlaxoSmithKline
- Location
- Dublin, CA + 130 other US sites
- Eligibility basics
- Ages 65+
- RecruitingHealthy volunteersPhase 3
Study to Learn About Safety, Tolerability, and Immune Response of a Catch-up Pneumococcal Vaccine in Children and Adolescents
Pfizer
- Location
- Fair Oaks, CA + 49 other US sites
- Eligibility basics
- Ages 1–17
- RecruitingHealthy volunteersPhase 4
A Study to Learn About a COVID-19 Vaccine in Healthy Adults 18 Through 64 Years of Age
BioNTech SE
- Location
- Walnut Creek, CA + 4 other US sites
- Eligibility basics
- Ages 18–64
- RecruitingHealthy volunteersPhase 3
A Study on the Immune Response and Safety of an Investigational Combined Measles, Mumps, Rubella and Varicella Vaccine, When Administered as Intramuscular Injection to Healthy Children 15 Months to 6 Years of Age
GlaxoSmithKline
- Location
- Walnut Creek, CA + 14 other US sites
- Eligibility basics
- Ages 1–6
- RecruitingHealthy volunteersPhase 3
A Study on the Safety of an Investigational Chickenpox Vaccine, When Given to Healthy Children, 12 to 15 Months of Age
GlaxoSmithKline
- Location
- Huntington Park, CA + 14 other US sites
- Eligibility basics
- Ages 1–1
- RecruitingHealthy volunteersPhase 3
A Study on the Immune Response and Safety of an Investigational Chickenpox Vaccine When Given to Healthy Children 12 to 15 Months of Age
GlaxoSmithKline
- Location
- Canoga Park, CA + 46 other US sites
- Eligibility basics
- Ages 1–1
- RecruitingHealthy volunteersPhase 3
A Study on the Immune Response and Safety of an Investigational Chickenpox Vaccine and a Marketed Measles, Mumps and Rubella Vaccine When Administered as Intramuscular Injection to Healthy Children 12 to 15 Months of Age
GlaxoSmithKline
- Location
- Huntington Park, CA + 12 other US sites
- Eligibility basics
- Ages 1–1
- RecruitingHealthy volunteersPhase 2
A Study to Learn About mRNA Vaccines Against Influenza in Adults
Pfizer
- Location
- Walnut Creek, CA + 14 other US sites
- Eligibility basics
- Ages 18+
- RecruitingPhase 3
A Study to Learn About Revaccination With a Vaccine Called RSVpreF in Immunocompromised Adults
Pfizer
- Location
- Los Angeles, CA + 12 other US sites
- Eligibility basics
- Ages 18+
Who these studies look for
Vaccine studies often exclude people who recently received a related vaccine or had the infection, and those with conditions or medicines that affect the immune system.
Matching a page like this one never means you qualify. Each research team decides eligibility at screening.
Questions
Could I receive a placebo?
Often yes. Many vaccine trials are randomized, so some participants receive a comparison vaccine or placebo. The consent document explains this.