SYN023 (Zamerovimab and Mazorelvimab) after rabies exposure in children

A Real-World Registry Study to Evaluate Clinical Protection Outcomes Following Post-Exposure Prophylaxis With Zamerovimab and Mazorelvimab Injection in Combination With Rabies Vaccine in Pediatric With Category III Rabies Exposure

This project will see if SYN023 (Zamerovimab and Mazorelvimab) given with rabies vaccine helps children under 18 who had severe (WHO Category III) rabies exposures stay rabies-free at 3 months and 1 year.

Quick facts

• Study type: Observational
• Enrollment: 232 (estimated)
• Ages: 0 Years to 17 Years
• Sex: All
• Sponsor: Synermore Biologics (Suzhou) Co., Ltd. (Industry-sponsored)
• Drugs / interventions: Zamerovimab, Mazorelvimab
• Locations: 6 sites (Beijing, Beijing Municipality and 5 other locations)
• Trial ID: NCT07327307 on ClinicalTrials.gov

What this trial studies

This is an open-label, prospective, multi-center observational study enrolling children under 18 who received passive immunization with Zamerovimab and Mazorelvimab (SYN023) or other passive products plus rabies vaccine as real-world post-exposure prophylaxis. Clinical rabies-free survival status will be recorded at Day 90 and Day 365, with optional Day 7 blood draws for rabies virus neutralizing antibody (RVNA) testing. All adverse events within 42 days and serious adverse events within 126 days after PEP administration will be collected. Enrollment requires WHO Category III exposure with PEP initiated within 7 days and guardian consent/assent per age rules.

Who should consider this trial

Good fit: Children under 18 with WHO Category III rabies exposure who began PEP (including passive immunization with Zamerovimab and Mazorelvimab or other passive products and the first rabies vaccine dose) within 7 days and whose guardian can provide informed consent are ideal candidates.

Not a fit: Adults, children without WHO Category III exposures, those who did not receive passive immunization or vaccine within the required timeframe, or those unable to complete follow-up are unlikely to benefit from participation.

Why it matters

Potential benefit: If successful, the data could support that SYN023 plus vaccine provides reliable protection and an acceptable safety profile for children after severe rabies exposures.

How similar studies have performed: Monoclonal-antibody–based passive immunization for rabies has shown promising safety and immunogenicity in prior adult studies, but pediatric real-world outcome data remain limited.

Eligibility criteria

Inclusion Criteria:

1. Age under 18 years on the day of enrollment, regardless of gender, and able to provide legal proof of identity;
2. Individuals with WHO Category III rabies exposure, and the time from exposure to the initiation of Post-Exposure Prophylaxis (PEP) is \<7 days;
3. Have completed standardized wound management, injection of Zamerovimab and Mazorelvimab Injection /other passive immunization products, and the first dose of rabies vaccination within 24 hours prior to screening;
4. The volunteer's guardian voluntarily agrees to their participation in the study and signs the informed consent form. Specifically: for volunteers under 8 years old, the guardian signs the informed consent form with the child's assent fully respected; for volunteers aged 8-17, the guardian signs the informed consent form, and the minor volunteer signs the minor assent form;
5. Willing and able to comply with all study procedures, and is expected to be able to complete the full course of rabies vaccination and the 1-year follow-up as required (with no plans for long-term absence or relocation from the study area).

Exclusion Criteria:

1. Based on inquiry, besides the current Category III rabies exposure, there is a history of bites by dogs, cats, mongooses, foxes, ferrets, skunks, bats, or raccoons within the past year;
2. Other conditions considered by the investigator as unsuitable for participation in this study.

Where this trial is running

Beijing, Beijing Municipality and 5 other locations

• Peking University First Hospital — Beijing, Beijing Municipality, China (Recruiting)
• Shenzhen second people's hospital — Shenzhen, Guangdong, China (Recruiting)
• The University of Hong Kong - Shenzhen Hospital — Shenzhen, Guangdong, China (Recruiting)
• Hunan Provincial People's Hospital — Changsha, Hunan, China (Recruiting)
• Affiliated Nanhua Hospital, University of South China — Hengyang, Hunan, China (Recruiting)
• Jiangxi Provincial Chest Hospital — Nanchang, Jiangxi, China (Recruiting)

Study contacts

• Study coordinator: Xiangjun Li

Conditions Rabies Post-exposure Prophylaxis; rabies; SYN023; pediatric