New quadrivalent flu vaccine shows promise for kids under 3
NCT ID NCT05779020
First seen Jun 25, 2026 · Last updated Jun 26, 2026 · Updated 1 time
Summary
This completed Phase 3 trial tested a quadrivalent (four-strain) influenza vaccine from Instituto Butantan in over 1,300 healthy infants and children aged 6 to 35 months. The study compared the immune response and safety of two doses (0.25ml and 0.50ml) against standard trivalent (three-strain) flu vaccines. The goal was to see if the quadrivalent vaccine provides better protection against both B strains of the flu virus.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Quadrivalent influenza vaccine (split virion, inactivated)
- What this could lead to
- If successful, this vaccine could provide broader protection against four flu strains for young children, reducing flu-related illness and hospitalizations.
- What could go wrong
- This is a completed Phase 3 trial, but results are not yet published. The vaccine may not show significantly better protection than existing trivalent vaccines, and side effects like fever or injection-site reactions are possible.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 3
Large-scale testing in a bigger group. Usually the last step before a treatment can be approved.
- Participants
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1,373 people
The number who actually took part.
- Started
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Apr 2023
- Finished
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Aug 2025
- Lead sponsor
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A government agency
The lead sponsor is a government body.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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6 to 35 months
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. Healthy infant and child of either sex aged between 6 and 35 months on the day of the first study vaccination. 2. Born at term (≥ 37 weeks of gestational age) and birth weight ≥ 2.5 kg. 3. Parents/legal guardians of the infant or child able and willing to attend all scheduled visits and comply with all study procedures, including blood draws. 4. Parents/legal guardians of the infant or child have provided informed consent. Exclusion Criteria: 1. Having received any influenza vaccine from the current season and/or 6 months before the first study vaccination. 2. History of allergy to egg, chicken proteins, or other components of the influenza vaccine. 3. History of serious adverse reaction to any influenza vaccine. 4. Have any clinically significant condition or situation that, in the Investigator's opinion, would interfere with study evaluations or participation. 5. History of Guillain-Barré or other demyelinating diseases. 6. History of neurological disease and/or clinically significant developmental delay (at the discretion of the Investigator), or seizure (except for an isolated febrile seizure episode). 7. Having received immune globulin, blood, or any blood product 3 months before the planned date of the first study vaccination or planned administration during the study period. 8. Any confirmed or suspected immunosuppressive condition, congenital or acquired immunodeficiency (including human immunodeficiency virus - HIV) based on medical history and physical examination. 9. Immediate personal or family history of congenital immunodeficiency. 10. Having received or are using radiation therapy, chemotherapy, immunosuppressive drugs, or other immunomodulatory drugs within three months before the planned date of the first study vaccination or planned use during the study. 11. Be a solid organ or bone marrow/stem cell transplant recipient. 12. Thrombocytopenia, bleeding disorder, use of anticoagulants, or any condition that contraindicates intramuscular injection. 13. Significant chronic disease (cancer, autoimmune disease, diabetes mellitus, acute or progressive liver disease, acute or progressive kidney disease, severe heart or lung disease) or which in the Investigator's opinion poses a risk to the health of the infant or child participating in the study or which may interfere with the conduct or conclusion of the study. 14. History of seropositivity for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C. 15. Major surgery or surgery using general anesthesia planned to occur during the period between the first vaccination and 28 days after full vaccination in the study. 16. Any condition that, in the opinion of the Investigator, may interfere with the conduct or completion of the study (such as travelling or planned moving of residence, among others). 17. Participation in another clinical trial involving another experimental or unregistered product 1 year before the planned date of the study's first vaccination, or plans to entering a clinical trial during the study. 18. Infant and institutionalized child. 19. Be related to the Investigator, research site staff member, or employee directly involved in the study. Postponement Criteria: 1. Have received any vaccine (including routine childhood vaccines) within 28 days of the first study vaccination (delay until the 28-day deadline from the date of the last vaccination). 2. Moderate or severe (as judged by the Investigator) acute illness/infection or febrile illness (temperature ≥ 37.8°C) 48 hours before the planned date of the first study vaccination. 3. Acute respiratory illness within 14 days preceding the planned date of the first study vaccination.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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A2Z Clinical Centro Avançado de Pesquisa Clínica Ltda.(Site 001)
Valinhos, São Paulo, 13271-130, Brazil
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CPMC Pesquisa Clínica - Clinica De Alergia Martti Antila Sorocaba
Sorocaba, São Paulo, 18040-425, Brazil
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CPQuali Pesquisa Clínica Ltda (Site 002)
São Paulo, 01228-000, Brazil
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Centro Oncológico de Roraima - CECOR (Site BVB-01)
Boa Vista, Roraima, 69304-015, Brazil
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Centro de Pesquisa Clínica S (Site RAO03)
Serrana, São Paulo, Brazil
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Centro de Pesquisa Clínica do Instituto da Criança - Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (Site SAO08)
São Paulo, 05403-000, Brazil
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Centro de Pesquisas Clínicas da Universidade Federal de Sergipe (Site AJU01)
Laranjeiras, Sergipe, 49170-000, Brazil
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Hospital das Clínicas da Faculdade de Medicina Ribeirão Preto - USP (Site RAO 04)
Ribeirão Preto, São Paulo, 14051-140, Brazil
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Instituto Auto Imune de Pesquisa e Educação Continuada - Real Hospital Português de Beneficência em Pernambuco (Site REC01)
Recife, Pernambuco, Brazil
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Instituto de Pesquisa PENSI (Site SAO09)
São Paulo, 01228-200, Brazil
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Other studies related to the condition(s) this trial covers.
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