Merck Animal Health Launches Non-Adjuvanted NOBIVAC NXT Rabies Vaccines for Dogs and Cats Amid Rising US Rabies Exposure Reports

Merck Animal Health has announced the US availability of two next-generation rabies vaccines for dogs and cats, expanding its NOBIVAC NXT companion-animal vaccine portfolio. The new products—NOBIVAC NXT 1-Rabies and NOBIVAC NXT 3-Rabies—use a non-adjuvanted formulation and are designed to provide one-year and three-year rabies protection, respectively, subject to their prescribed vaccination schedules.

The launch comes against a backdrop of increased reports of human exposure to rabid or potentially rabid animals in the United States. On 10 September 2026, the US Centers for Disease Control and Prevention (CDC) issued a nationwide Health Alert Network advisory highlighting increased rabies-related exposure reports and post-exposure prophylaxis (PEP) activity during the summer.

Although Merck has not presented the vaccine launch as a direct response to the CDC advisory, the timing reinforces the importance of companion-animal vaccination as a component of integrated rabies prevention.

Two formulations, one next-generation vaccine platform

The newly launched products are indicated for healthy dogs and cats aged 12 weeks and older.

Key product characteristics include:

• Non-adjuvanted formulation: Designed without conventional vaccine adjuvants.

• Low-volume administration: A 0.5 mL dose for both dogs and cats.

• No preservatives, antibiotics or thimerosal: As stated in the manufacturer’s product information.

• Two duration-of-immunity options: One-year and three-year formulations.

• Species coverage: Both dogs and cats.

The three-year product, NOBIVAC NXT 3-Rabies, is administered as a 0.5 mL subcutaneous dose, followed by a booster one year later. Subsequent revaccination is scheduled every three years under the US product label. The one-year formulation provides the corresponding one-year protection option.

Merck describes the NXT platform as a next-generation vaccine technology designed to stimulate protective immune responses without the need for an adjuvant. The company is positioning the products around both preventive protection and the vaccination experience, including lower-volume administration.

The manufacturer reports that 100% of vaccinated cats and dogs in the supporting studies were protected against rabies three years after vaccination for the three-year formulation. This is a study-specific product claim and should not be interpreted as a guarantee of absolute protection in every vaccinated animal.

CDC reports a measurable increase in human rabies exposure activity

The launch coincides with a significant public-health warning. In its 10 September advisory, the CDC reported that:

• Rabies-related inquiries increased 17% between July and August 2026 compared with the same period in 2025.

• At least eight state health departments reported increased rabies PEP use, PEP administration errors, or both.

• Weekly pharmacy data through 2 September showed estimated utilisation increases of 33% for human rabies vaccines and 76% for human rabies immunoglobulin (HRIG) compared with the corresponding period in 2025.

• Approximately 1.4 million people in the US seek medical evaluation annually after animal contact, while around 100,000 receive rabies PEP following potential exposure.

The CDC advisory covered exposures involving known rabies vectors as well as animals in which rabies is less commonly reported. Several mass-exposure events also reinforced the need for accurate exposure assessment and appropriate PEP administration.

These figures reflect human exposure reporting and healthcare utilisation; they do not establish a comparable nationwide increase in confirmed animal rabies incidence.

Rabies remains one of the most serious zoonotic infections. Once clinical symptoms develop, the disease is almost invariably fatal. Vaccination of dogs and cats helps reduce the risk of transmission from infected animals to people and other animals.

Why non-adjuvanted formulation matters

Adjuvants are incorporated into many conventional vaccines to enhance immune responses. Merck’s NXT platform is designed to achieve the intended immune response without these components.

The commercial proposition centres on a combination of formulation design, low-volume administration and duration-of-immunity options. A single 0.5 mL presentation for both dogs and cats may also simplify handling and administration in veterinary practices.

However, non-adjuvanted should not automatically be interpreted as superior clinical protection or an absence of adverse reactions. Comparative claims require appropriately designed head-to-head safety and immunogenicity evidence. The relevant product label remains the authority for vaccination schedules, precautions and use.

Market implications for the companion-animal vaccine sector

Rabies vaccination is a foundational preventive-care category in companion-animal medicine. The launch expands Merck’s differentiated vaccine portfolio and gives veterinary practices another product option in a market where adherence, convenience and owner confidence influence preventive-care decisions.

The product may be particularly relevant to clinics seeking a low-volume, non-adjuvanted option with a three-year duration-of-immunity label. It also reinforces the importance of maintaining vaccination coverage in areas where domestic animals and wildlife interact.

The launch should nevertheless be understood as a US market introduction. Availability, product registration and approved vaccination schedules may differ across international markets.

Industry outlook

NOBIVAC NXT Rabies represents a formulation and administration innovation within an established vaccine category. Its commercial performance will depend on veterinary adoption, product availability, price positioning and evidence supporting its safety and protective performance in routine practice.

Bottom line: Merck’s NOBIVAC NXT 1-Rabies and 3-Rabies expand the US companion-animal rabies vaccine portfolio with non-adjuvanted, 0.5 mL formulations for dogs and cats. Against a backdrop of increased human rabies exposure reports, the launch highlights the continuing importance of veterinary vaccination in One Health rabies prevention.