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NCT Number: NCT06838195

Clinical Trial of the S. Flexneri-S. Sonnei Bivalent Conjugate Vaccine

The goal of this clinical trial is to evaluate the protective efficacy of S. Flexneri-S. Sonnei bivalent conjugate vaccine against diarrhea caused by Shigella infection in infants and children aged 6 months to 5 years. Researchers will observe the incidence of diarrhea of any severity due to Shigella flexneri and Shigella sonnei infection 30 days after full immunization. The subjects will receive 2 doses of vaccination.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

Dysentery Bacterial Infections Bacterial Infections and Mycoses Digestive System Diseases Dysentery, Bacillary Dysentery, Shigella Enterobacteriaceae Infections Gastroenteritis Gastrointestinal Diseases Gram-Negative Bacterial Infections Infections Intestinal Diseases

Age range

6 month–5 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Icddr,B

Dhaka, 1216, Bangladesh

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Infants and children aged 6 months to 5 years.
  • Legal guardians voluntarily agree to participate in the study and sign an informed consent form.
  • Legal guardians agree to comply with the requirements of the clinical trial protocol and are willing and able to participate in all planned follow-ups.
  • The subject's guardian agrees that the subject should not abuse antibiotics. If needed，antibiotics should be used under the guidance of a doctor and avoid taking antibiotics on their own during the clinical trial.
  • Based on medical history, physical examination, and the investigator's judgment, the subject is determined to be in good health.

Exclusion criteria

  • History of confirmed bacterial dysentery in the past 6 months.
  • Serious allergy to tetanus toxoid, history of severe allergies, fever above 39.5°C following previous vaccination with a prophylactic biological product.
  • Currently suffering from serious intestinal diseases, symptoms of diarrhea, abdominal pain, or bloody purulent stools in the past 15 days.
  • Diagnosed pathological jaundice currently.
  • Confirmed diagnosis of thrombocytopenia or other coagulation disorders.
  • Known or suspected immunological deficiencies (e.g., perianal abscesses indicating potential immune deficiency in infants and young children), long-term treatment (≥14 days) with immunosuppressants within half a year before vaccination (radiotherapy, chemotherapy, systemic corticosteroids ≥2 mg/kg/day, antimetabolites, cytotoxic drugs), or parents confirmed to have HIV infection.
  • Receipt of immunoglobulins/blood products (except hepatitis B immunoglobulin) within 3 months before vaccination.
  • Severe congenital anomalies (important organ function impairment), severe malnutrition, developmental disorders, severe hereditary diseases.
  • Currently suffering from the following diseases:
  • Severe liver or kidney diseases, cardiovascular diseases, malignant tumors, and other severe chronic diseases.
  • Diagnosed serious infectious diseases, such as tuberculosis, viral hepatitis, etc.
  • Severe asthma.
  • Generalized rashes, dermatophytosis, skin suppuration, or blistering.
  • Convulsions, epilepsy, encephalopathy, psychiatric disorders or family history of psychiatric disorders.
  • Planning to participate or currently participating in other vaccine or drug clinical trials.
  • Any condition that the investigators believe may affect the evaluation of the study.

Treatment and study plan

S. Flexneri-S. Sonnei bivalent conjugate vaccine

Biological

Subjects receive two doses of the vaccine on the day of randomisation (day 0) and day 30.

Placebo

Biological

Subjects receive two doses of the placebo on the day of randomisation (day 0) and day 30.

Primary outcomes

  1. The protective efficacy of S. Flexneri-S. Sonnei bivalent conjugate vaccine

    Time frame: From day 30 post full immunization to the subsequent 24-month period.

    The efficacy will be assessed by comparing the incidence rate of laboratory-confirmed S. flexneri-associated or S. sonnei-associated diarrhea between the vaccinated group and the placebo group.

    Statistical Analysis:

    Protective efficacy(%)=(control group incidence (person-year incidence)- vaccine group incidence (person -year incidence))/control group incidence (person-year incidence)x100%

Secondary outcomes

  1. The protective efficacy against diarrhea cases with positive bacterial culture for Shigella species

    Time frame: From he first dose of immunization to 24-month period post full immunization.

    Evaluation of the protective efficacy of the vaccine against diarrhea cases with positive bacterial culture for Shigella species.

  2. Positive PCR testing for Shigella species

    Time frame: From day 30 post full immunization to the subsequent 24-month period.

    Evaluation of diarrhea cases with positive PCR testing for Shigella species

  3. IgG antibody seroconversion (fourfold increase) rate on day 30 post full immunization for subgroup 1.

    Time frame: The 30th day after two doses of the vaccine.

    Subjects in immunogenicity subgroup 1, vaccine serotype-specific Shigella flexneri and Shigella sonnei IgG antibody seroconversion (fourfold increase) rate on day 30 post full immunization.

  4. IgG antibody concentration on day 30 post full immunization for subgroup 1.

    Time frame: The 30th day after two doses of the vaccine.

    For subjects in immunogenicity subgroup 1, vaccine serotype-specific Shigella flexneri and Shigella sonnei antibody concentration on day 30 post full immunization.

  5. IgG antibody seroconversion (fourfold increase) rate on day 30 post full immunization for subgroup 2.

    Time frame: From 30 day to 1 year after the first immunization.

    For subjects in immunogenicity subgroup 2, vaccine serotype-specific Shigella flexneri and Shigella sonnei IgG antibody seroconversion (fourfold increase) rate on day 30 post the first dose, day 30 post full immunization, half a year after the first immunization, and one year after the first immunization.

  6. IgG antibody concentration on day 30 post full immunization for subgroup 2.

    Time frame: From 30 day to 1 year after the first immunization.

    For subjects in immunogenicity subgroup 2, vaccine serotype-specific Shigella flexneri and Shigella sonnei antibody concentration on day 30 post the first dose, day 30 post full immunization, half a year after the first immunization, and one year after the first immunization.

  7. AEs within 0-30 minutes after vaccination

    Time frame: Within 30 minutes after each dose of vaccine

    The occurrence of any adverse events within 30 minutes after each dose of vaccine (number of instances, number of cases, incidence rate, and the relationship to the vaccine administration)

  8. Solicited AEs within 0-7 days after vaccination

    Time frame: Within 0-7 days after each vaccine dose.

    The occurrence of solicited adverse events from Day 0 to Day 7 after each vaccine dose (number of instances, number of cases, incidence rate, and the relationship to the vaccine administration)

  9. Unsolicited AEs within 0-30 days after vaccination

    Time frame: Within 0-30 days after each vaccination

    The occurrence of unsolicited adverse events from Day 0 to Day 30 after each vaccine dose (number of instances, number of cases, incidence rate, and the relationship to the vaccine administration).

  10. SAE within 0-6 months after primary immunization

    Time frame: Within 0-6 months after primary immunization.

    The occurrence of Serious Adverse Events (SAEs) from after the first dose to 6 months after complete immunization (number of instances, number of cases, incidence rate, and the relationship to the vaccine administration)

Sponsors and collaborators

Lead sponsor

Beijing Zhifei Lvzhu Biopharmaceutical Co., Ltd

Industry

Registry information

Official study title

A Randomized, Double-blind, Placebo-controlled Phase III Clinical Trial Evaluating the Protective Efficacy, Immunogenicity, and Safety of the S. Flexneri-S. Sonnei Bivalent Conjugate Vaccine in Infants and Children Aged 6 Months to 5 Years in Bangladesh

Important dates

Study start
2025
Primary completion
2028
Study completion
2028
First posted
Feb 20, 2025
Registry last updated
Apr 1, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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