Silevimig Approved for Rabies Passive Immunization: The First Approved Bispecific Antibody for Rabies Prevention Worldwide
On June 22, 2026, China’s National Medical Products Administration (NMPA) officially approved Silevimig Injection (Jinsuxi®), independently developed by Genrix Biopharmaceutical, for rabies passive immunization in adults following exposure to Rabies Virus (RABV).
The approval of Silevimig approved for rabies passive immunization not only fills a major gap in the field of rabies bispecific antibodies but also makes Silevimig the world’s first approved bispecific antibody for post-exposure prophylaxis (PEP) against rabies. ✨
This milestone marks the beginning of a new era of antibody-based rabies prevention.
HongKong DengYue Medicine will take a closer look at the mechanism of action, clinical data, and the significance of Silevimig approved for rabies passive immunization in the field of rabies prevention.
Silevimig: The World’s First Bispecific Antibody for Rabies
Silevimig is a recombinant fully human bispecific antibody developed by Genrix Biopharmaceutical to target rabies virus.
🎯 The antibody specifically binds to two critical epitopes on the rabies virus glycoprotein (G protein), namely Epitope I and Epitope III.
By simultaneously targeting multiple antigenic sites, Silevimig can:
- Block the binding of rabies virus to host cell receptors;
- Prevent viral invasion of the nervous system;
- Provide immediate immune protection before rabies vaccines generate sufficient protective antibodies;
- Reduce the risk of rabies infection after exposure.
This design aligns with recommendations from the World Health Organization (WHO), which advocates antibody cocktails targeting multiple antigenic sites to improve effectiveness against diverse rabies virus strains and genotypes.
Compared with conventional monoclonal antibodies, bispecific antibodies offer broader and more stable virus-neutralizing activity, providing a new solution for rabies passive immunization.
Why Is Passive Immunization Necessary for Rabies Post-Exposure Prophylaxis (PEP)?
Rabies is a zoonotic disease caused by rabies virus infection.
❗❗ Once clinical symptoms appear, the disease is almost always fatal, with a mortality rate approaching 100%, making it one of the deadliest infectious diseases worldwide.
According to rabies prevention guidelines and WHO recommendations, individuals with Category III exposure should receive: 🔽
- Immediate and thorough wound cleansing;
- Rabies vaccination;
- Passive immunization products.
Among these measures, passive immunization plays a particularly critical role.
Rabies vaccines typically require 7–14 days to induce adequate levels of neutralizing antibodies. During this window period, the virus may enter the nervous system, making immediate protection through externally administered antibodies essential.
Traditional passive immunization products mainly include:
Human Rabies Immunoglobulin (HRIG)
Advantages:
- Long history of clinical use;
- Proven efficacy.
Limitations:
- Dependent on human plasma supply;
- Limited availability;
- High production costs;
- Potential theoretical risk of blood-borne pathogen transmission.
Equine Rabies Immunoglobulin (ERIG)
Advantages:
- Lower cost.
Limitations:
- Higher risk of allergic reactions;
- Potential for serum sickness and other adverse events.
As a result, antibody-based therapies with improved safety, scalable manufacturing, and consistent quality have become an important development trend. The approval of Silevimig approved for rabies passive immunization represents a significant innovation in this direction.
Phase III Clinical Trial Results Supported Approval
The approval of Silevimig approved for rabies passive immunization was primarily supported by positive results from a randomized, double-blind, parallel-group Phase III clinical study.
Study Overview
- Clinical registration number: NCT05846568 / CTR20222502
- Study design: Randomized, double-blind Phase III trial
- Number of participants: 1,200
- Indication: Passive immunization for adults with suspected Category III rabies exposure
Genrix Biopharmaceutical previously announced that the study met its primary efficacy endpoint. 📊
Although complete data have not yet been publicly released, earlier clinical findings demonstrated promising efficacy.
Key Clinical Findings
In the GR1801-002 study, Silevimig demonstrated rapid and sustained neutralizing antibody responses.
✅ Rapid Onset of Action
At a single-agent dose of 0.05 mg/kg:
- Onset time was comparable to HRIG;
- Antibody titers reached similar levels;
- Positive response rates were comparable;
- Time to peak response was similar.
✅ Superior Performance When Combined with Vaccination
When administered alongside rabies vaccines:
- 0.05 mg/kg dose group
- 0.1 mg/kg dose group
Both achieved significantly higher antibody titers within the first seven days compared with the standard HRIG-plus-vaccine regimen.
✅ Outstanding Seropositivity Rates
Clinical data showed:
- 97.37% seropositivity on Day 1 in the high-dose group;
- 100% seropositivity on Day 1 in the low-dose group;
- Sustained 100% seropositivity through Day 7.
These results indicate that Silevimig can provide rapid immune protection following rabies exposure.
Pediatric and Adolescent Development Is Ongoing
In addition to its adult indication, Genrix Biopharmaceutical is actively advancing clinical development in pediatric and adolescent populations.
In July 2025, Chinese regulators approved a clinical trial evaluating: 👇
- Indication: Passive immunization following rabies exposure in children and adolescents aged 2 to under 18 years
- Clinical phase: Phase III
- Registration number: CTR20253293
If successful, Silevimig approved for rabies passive immunization could eventually benefit a much broader patient population.
China’s Rabies Antibody Market Enters the Antibody Era
With Silevimig approved for rabies passive immunization, China now has three approved rabies antibody products.
Ormutivimab
- Company: North China Pharmaceutical
- Type: Monospecific antibody
- Approved: 2022
Zamerovimab and Mazorelvimab
- Company: Synermore Biologics
- Type: Antibody combination product
- Approved: 2024
Silevimig
- Company: Genrix Biopharmaceutical
- Type: Bispecific antibody
- Approved: 2026
- World’s first approved rabies bispecific antibody
Meanwhile, North China Pharmaceutical’s rabies antibody combination candidate NM57S/NC08 has already entered Phase III development.
More innovative antibody therapies are expected to enter the rabies passive immunization market in the coming years.
The Significance of Silevimig’s Approval
The approval of Silevimig approved for rabies passive immunization represents more than a new product launch; it signals an important technological shift in rabies prevention.
Compared with conventional immunoglobulin products, Silevimig offers several potential advantages:
- Fully human antibody design;
- No dependence on plasma-derived materials;
- Lower batch-to-batch variability;
- Greater manufacturing scalability;
- Improved safety potential;
- Broader viral coverage.
As innovative antibody therapies continue to advance through clinical development and commercialization, rabies post-exposure prophylaxis is expected to gradually transition from traditional blood-derived products to engineered antibody-based solutions.
Conclusion
Rabies remains one of the deadliest infectious diseases in the world, and post-exposure prophylaxis (PEP) continues to be the most effective prevention strategy.
🐱🏍 As the world’s first approved bispecific antibody for rabies passive immunization, Silevimig approved for rabies passive immunization provides a promising new option for patients while validating the potential of antibody therapies as alternatives to traditional rabies immunoglobulins.
With pediatric development progressing, international expansion underway, and more innovative antibody products entering the market, rabies prevention is entering a new era driven by biologic therapies.
China pharmaceutical wholesaler DengYueMed will continue to monitor developments in innovative Chinese medicines and help international patients access emerging therapies, connecting global patients with China’s high-quality healthcare resources and pharmaceutical innovations.
FAQ about Silevimig Approved for Rabies Passive Immunization
What is the passive vaccine for rabies?
A passive rabies immunization is not a vaccine but an antibody-based treatment given after rabies exposure. Products such as rabies immunoglobulin (RIG) or monoclonal antibodies provide immediate protection until the rabies vaccine stimulates the body’s own immune response.
Is passive immunization a vaccine?
No. Passive immunization is not a vaccine. It provides immediate protection through pre-formed antibodies, whereas vaccines stimulate the body’s immune system to produce its own protective antibodies over time.
Is 10 days too late for PEP rabies?
Not necessarily. Rabies post-exposure prophylaxis (PEP) should be started as soon as possible after exposure, but it may still be effective if initiated 10 days later, depending on the circumstances. Anyone with a potential rabies exposure should seek medical evaluation immediately.
What passive immunization products are available for rabies?
Rabies passive immunization products include human rabies immunoglobulin (HRIG), equine rabies immunoglobulin (ERIG), and newer rabies-neutralizing antibody therapies such as Silevimig, the world’s first approved bispecific antibody for rabies passive immunization.
