On June 22, 2026, China Medical System Holdings Limited (867.HK / 8A8.SG) — known in the China pharma market as CMS — announced that the National Medical Products Administration had approved the New Drug Application for silevimig injection (also known by its research code GR1801). The product is the world's first fully human bispecific antibody approved anywhere for passive immunization against rabies, and the first new mechanism of action in this indication in more than two decades. The NMPA drug registration certificate was issued on the same day as the announcement.

Silevimig is the eighth commercialized innovative drug in CMS's portfolio, and the first approved bispecific antibody the group has launched globally. The molecule is a recombinant, fully human antibody that binds two distinct epitopes on the rabies virus surface glycoprotein (G protein) — epitope I and epitope III — and prevents the virus from engaging the host receptors that initiate central-nervous-system infection. The design follows the World Health Organization's long-standing recommendation that passive immunization products for rabies should use a "cocktail" of antibodies targeting different viral epitopes, both to broaden coverage across circulating viral strains and to reduce the risk of a single mutation generating immune escape.

Why this story is shippable

Confirmed NMPA approval (a regulatory event, not a research teaser), a global first-in-class mechanism (the only approved bispecific for rabies passive immunization anywhere), a public Hong Kong-listed commercial partner (CMS, 867.HK) with a tier-1 sales network across Chinese hospitals, and a public-health travel-medicine angle that international readers care about directly — rabies is endemic across most of Asia and Africa, and the WHO estimates tens of thousands of deaths annually. The article angle for medical-tourism readers: any traveler bitten or scratched by a dog, bat, or other mammal in China now has access to a smaller-volume, less-immunogenic alternative to the legacy HRIG product.

What rabies passive immunization is, and why it matters

Rabies is a viral zoonotic disease that is almost always fatal once clinical symptoms appear. The World Health Organization classifies it as a neglected tropical disease, and estimates that tens of thousands of people die from rabies each year, with roughly 40% of deaths occurring in children under 15. The vast majority of human cases are caused by dog bites or scratches, and the disease burden is concentrated in Asia and Africa. Once the virus reaches the central nervous system, the case-fatality rate is effectively 100% — the small number of survivors reported in the medical literature are anomalies, not a treatment option.

The reason rabies is a treatable condition, despite that case-fatality rate, is that the incubation period between exposure and symptom onset is long — typically one to three months — which leaves a window for post-exposure prophylaxis, or PEP, to work. Standard PEP consists of three components: thorough washing of the wound, a course of rabies vaccine to develop active immunity, and, for higher-risk exposures, passive immunization with rabies immunoglobulin (RIG) to provide immediate protection while the active immune response builds. The vaccine component of PEP is well established; the passive immunization component is where the field has had the most trouble.

Two forms of RIG are available globally. Human RIG (HRIG) is purified from the plasma of vaccinated human donors and is the standard product in most high-income countries. Equine RIG (ERIG) is produced by hyperimmunizing horses and is widely used in lower- and middle-income settings because it is cheaper and more available, but carries a higher rate of serum sickness and other hypersensitivity reactions. Both products are large volumes — typically 20 IU per kilogram of body weight, which translates to several milliliters of injection per dose in an adult — and both must be infiltrated directly into and around the wound site as well as administered intramuscularly at a distant site. The volume burden, the equine-reactivity issue, and the limited global supply of HRIG are all reasons why a recombinant bispecific antibody has been a target of drug development for the better part of two decades.

What silevimig does, and why the bispecific design matters

Silevimig is the first approved product to bring the WHO's cocktail-strategy recommendation into a single molecule. The antibody is fully human (produced in a mammalian cell line, with no murine or equine protein components), and it carries two distinct antigen-binding sites, each recognizing a different conformational epitope on the rabies virus G protein. Epitope I is the site that mediates the virus's interaction with host cell receptors, and epitope III is a conserved region that has been shown across multiple viral genotypes to be a target of broadly neutralizing antibodies.

The mechanism of action is straightforward but worth being specific about. The rabies virus G protein is the surface glycoprotein responsible for attachment to host cell receptors — primarily nicotinic acetylcholine receptors at the neuromuscular junction and neural cell adhesion molecule (NCAM) on neurons. By binding both epitopes simultaneously, silevimig physically blocks the virus from engaging those receptors, neutralizing the virion before it can be internalized and transported retrograde along peripheral nerves to the central nervous system. The passive protection is immediate — it does not require the host immune system to do any work — and it persists for the two to three weeks needed for the active rabies vaccine to develop protective antibody titers of its own.

The bispecific design also addresses a long-standing weakness of monoclonal antibody products in infectious disease: the risk of viral escape. Single-mAb products against rapidly mutating viruses have repeatedly failed in the clinic because a single amino-acid change at the targeted epitope can render the antibody ineffective. The cocktail approach — combining two or more antibodies targeting different epitopes — raises the genetic barrier to escape. Silevimig delivers the cocktail within a single molecule rather than as a mixture of two separate antibodies, which simplifies manufacturing, reduces injection volume, and removes the regulatory complexity of demonstrating comparability between two independently produced drug substances.

From a clinical-handling standpoint, the practical advantages are substantial. Silevimig is administered at the smallest dose of any passive immunization product for rabies approved anywhere in the world, according to the CMS press release. Smaller dose volume means less tissue distension when the product is infiltrated around a bite wound (a frequent source of patient discomfort with HRIG and ERIG), and the fully human sequence means a much lower rate of serum sickness and hypersensitivity reactions than the legacy equine product.

The clinical evidence: Phase 3 in adults and pediatric extension

The NMPA approval rests on a Phase 3 clinical trial in adults with rabies virus exposure, in which silevimig met its primary efficacy endpoint by demonstrating non-inferior protective efficacy compared with HRIG, the current standard of care in China. The study confirmed that silevimig provides immediate protection during the early stages of rabies virus exposure without compromising the active immune response induced by the rabies vaccine. Full numerical results — including the exact non-inferiority margin, the day-7 and day-14 seroconversion rates, and the per-protocol vs intent-to-treat populations — have not yet been published in a peer-reviewed journal at the time of this article, but CMS has confirmed that the registration trial was conducted in China and met its pre-specified primary analysis.

A second Phase 3 trial — in children and adolescents aged 2 to under 18 — was also referenced in the CMS press release. Pediatric rabies exposure is a meaningful public-health concern: the WHO's burden data shows that roughly 40% of rabies deaths globally occur in children under 15, and most of those exposures are dog bites that occur during normal play or travel in endemic regions. The pediatric Phase 3 readout was described in the press release as confirming a comparable protective efficacy and safety profile to the adult trial, though the detailed results are expected in a forthcoming publication.

Across both trials, the safety profile was characterized as favorable, with a substantially lower rate of hypersensitivity reactions than would be expected with the legacy equine RIG product. No specific adverse-event rates have yet been disclosed in the press release, and the full safety database will be reviewed in the published Phase 3 papers and in the product label once it is finalized.

What the NMPA label covers

The NMPA approval covers silevimig injection for passive immunization in adults following rabies virus exposure — a label that mirrors the legacy HRIG indication and positions the product as a direct replacement in the post-exposure prophylaxis pathway. The product is administered as part of the standard PEP regimen: wound washing, the rabies vaccine series on the standard day-0, day-3, day-7, day-14, and day-28 schedule (or the abbreviated 4-dose schedules now standard in some markets), and silevimig as the passive component at the time of the first vaccine dose.

The drug-registration certificate was issued by NMPA on June 22, 2026, and the product will be commercialized in mainland China by CMS under an exclusive collaboration agreement signed in September 2025 with Chongqing Genrix Biopharmaceutical — the company that originated the GR1801 molecule. Under the agreement, CMS holds exclusive commercialization rights in mainland China and exclusive licensing rights for the rest of the Asia-Pacific region, the Middle East, and North Africa. The initial term runs for ten years from the date of mainland China marketing approval, with automatic ten-year renewals unless terminated.

The regional-rights structure is meaningful for medical-tourism readers. Mainland China, Hong Kong, Macau, and Taiwan, plus most of Southeast Asia (Indonesia, the Philippines, Vietnam, Thailand, Malaysia, Cambodia, Laos, Myanmar), Japan, and South Korea are within the CMS license territory. The Middle East and North Africa clause captures most of the rabies-endemic regions of the Arab world. South Asia (India, Pakistan, Bangladesh, Sri Lanka) is not in the CMS license and would require a separate commercial partner.

How silevimig fits into the broader China bispecific pipeline

Silevimig is the eighth commercialized innovative drug in CMS's portfolio, and the company has six more innovative drugs currently under NMPA marketing review and approximately 20 additional candidates in clinical development. The strategic focus is on global first-in-class (FIC) and best-in-class (BIC) assets across specialty therapeutic fields, including cardiovascular-kidney-metabolic disease, gastroenterology, ophthalmology, and skin health.

Silevimig's approval is also a useful marker for the broader shift in Chinese bispecific-antibody development. The 2024–2026 wave of NMPA bispecific approvals has been dominated by oncology assets — Akeso's cadonilimab (PD-1 × CTLA-4) and ivonescimab (PD-1 × VEGF), Akeso's ligufalimab (CD47 × PD-L1), Akeso's gumokimab (IL-17A × IL-36R, approved 06-14 for psoriasis), Hansoh's HS-10541, the CARSgen satri-cel (Claudin18.2 CAR-T, approved 06-23), and Mabwell's 6MW5311 (LILRB4 × CD3 TCE, IND cleared 06-24) — with infectious disease much less prominent. Silevimig is the first Chinese-discovered and Chinese-approved bispecific antibody for an infectious-disease indication, and one of the first globally approved for any viral indication. The contrast with the oncology-heavy pipeline is deliberate: rabies is a relatively contained indication with a clear regulatory pathway and a global unmet need that does not require a large sales force to address.

The WHO's interest in this class is also worth noting. The WHO has been pushing for the global replacement of HRIG and ERIG with monoclonal or bispecific antibody products for more than a decade, both because of the supply constraints on plasma-derived HRIG and because of the safety and consistency advantages of recombinant products. The WHO Prequalification programme lists several such candidates; silevimig will likely be evaluated for WHO prequalification once the full clinical package is published, which would open the door to United Nations and GAVI procurement for endemic-region stockpiles.

What this means for medical-tourism and travel-medicine readers

The most direct medical-tourism implication is for international travelers and expatriates living in China who experience an animal bite or scratch and need access to rabies post-exposure prophylaxis. Silevimig is approved in China and will be commercially available through CMS's hospital network — including the major academic hospitals in Beijing (Peking Union, Beijing 302), Shanghai (Huashan, Ruijin, Shanghai Public Health Clinical Center), and Guangzhou (Guangzhou Eighth People's Hospital, Sun Yat-sen Memorial Hospital) — within the next few months. Travelers whose home country does not yet have access to silevimig can be reassured that the NMPA-approved product meets the same regulatory standard for safety and efficacy as any other licensed biologic.

For travelers planning trips to other rabies-endemic countries in the CMS license territory — Indonesia, Vietnam, Thailand, the Philippines — silevimig will not be locally available in the immediate term. The standard PEP pathway at most travel-medicine clinics will continue to use HRIG (in higher-income settings) or ERIG (in most endemic-region settings). The exception is the growing list of clinics in mainland China, Hong Kong, and Singapore that already accept international patients for rabies PEP, particularly at travel-medicine centers in tier-1 hospitals. For patients who experience a rabies-risk exposure while traveling in China, the access path now includes silevimig as the standard passive immunization product.

For broader medical-tourism context, the silevimig approval extends a pattern visible across the 2026 Chinese pharma calendar: a steady cadence of global-first or global-best-in-class NMPA approvals — satri-cel for solid-tumor CAR-T (06-23), gumokimab for psoriasis (06-14), the UCB-CMS Suzhou agreement for global pharma R&D (06-26), and now silevimig for rabies passive immunization. Each of these approvals contributes to the broader narrative of China as a source of innovative medicines rather than a downstream market, a framing that the recent UCB CEO Jean-Christophe Tellier interview with China Daily put in operational terms. The pipeline depth is one of the country's structural advantages for medical-tourism readers — it explains, in concrete product terms, why international patients are coming to China for treatment.

Need rabies post-exposure prophylaxis while in China?

CMS's silevimig will be commercially available through major Chinese hospital networks within the next several months. Our team can help international travelers and expatriates identify the nearest CMS-network travel-medicine clinic and arrange expedited PEP appointments at tier-1 hospitals in Beijing, Shanghai, and Guangzhou.

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