DIFF Biotech’s Innovative Nasal Spray Influenza Vaccine Receives Clinical Trial Approval, Introducing a New Attenuation Pathway

HANGZHOU, China, Feb. 9, 2026 /PRNewswire/ — Zhejiang Difference Biological Technology Co., Ltd. (DIFF Biotech) announced that its proprietary nasal spray influenza attenuated live vaccine, DIFF-flu, has recently received clinical trial approval as a Class 1.2 innovative vaccine from China’s National Medical Products Administration (NMPA).

As the first domestically self-developed nasal spray influenza vaccine in China to advance into clinical trial, DIFF-flu leverages a pioneering M2 gene–modified attenuation technology, protected by multiple international invention patents. This achievement underscores DIFF Biotech’s leading capabilities in respiratory infectious disease prevention and establishes an important foundation for future industrialization.

Dr. Jiasheng Song, Chief Executive Officer of DIFF Biotech, commented: “DIFF-flu’s clinical approval marks a major milestone for DIFF Biotech and a meaningful achievement for independent innovation in respiratory infectious disease prevention. As a next-generation attenuation platform, DIFF-flu is designed to achieve an optimal balance between immunogenicity and safety—an advance that holds significant potential for improving influenza protection. We believe this progress will help expand access to safer, more effective influenza prevention, particularly for older adults and other vulnerable populations. DIFF Biotech will continue to drive next-generation vaccine innovation to strengthen public health and contribute to global biomedical progress.”

A New Attenuation Strategy: Replication Restriction for Enhanced Safety

DIFF-flu is developed using an innovative M2 gene–modification strategy that produces a replication-restricted vaccine strain. This approach achieves a deliberate balance between robust attenuation and strong immunogenicity—generating a potent immune response while maintaining an exceptional safety profile. In essence, the technology places a “safety harness” on the virus to prevent uncontrolled replication.

Existing nasal spray influenza vaccines on the market rely on cold-adapted attenuation, allowing the vaccine virus to replicate efficiently only at lower temperatures such as those in the nasal cavity but limiting replication in the warmer lower respiratory system and lungs. Because these strains can still replicate in nasal mucosa and cause mild viral shedding, they are generally not recommended for older adults or immunocompromised individuals.

Preclinical data indicate that DIFF-flu offers a differentiated safety profile, with negligible viral shedding, and significantly reduced viral loads in respiratory tissues, suggesting the potential to extend nasal spray vaccine eligibility to older adults and other underserved groups.

Notably, preclinical data show that DIFF-flu confers 100% protection against epidemic strains circulating more than 50 years ago, while also eliciting strong immunity against contemporary variants.

Market Landscape: At-Home Use Policies Unlock Global Opportunities

The global influenza vaccine market is undergoing a period of structural evolution. While injectable vaccines remain the predominant format, they continue to face long-standing challenges such as suboptimal uptake and limited ability to curb viral transmission. Nasal spray vaccines—which induce mucosal immunity directly at the site of viral entry—represent an increasingly important direction for influenza prevention.

In September 2024, the U.S. FDA granted authorization for at-home administration of a related nasal spray influenza vaccine, paving the way for direct-to-consumer (DTC) distribution models. This regulatory milestone significantly improves convenience and accessibility for the public and creates favorable conditions for DIFF-flu’s future global introduction.

Global Influenza Burden Underscores the Need to Strengthen Herd Immunity

According to the World Health Organization (WHO), seasonal influenza infects up to 1 billion people each year, causing 3–5 million severe cases and 290,000–650,000 respiratory deaths globally.

Older adults account for the majority of influenza-related deaths and face heightened risks of complications such as pneumonia, myocarditis, encephalitis, and acute cardiorespiratory failure. Studies show that influenza vaccination can reduce hospitalization risk by 40–60%, making improved vaccine coverage especially critical for aging and medically vulnerable populations.

Despite this, vaccination rates remain low in many parts of the world. In China, influenza vaccination coverage is approximately 3.8%, far below mature markets such as the United States (around 49.3%). Increasing vaccination uptake is essential to protect high-risk groups and strengthen community-level immunity.

About DIFF Biotech

Zhejiang Difference Biological Technology Co., Ltd. (DIFF Biotech) is a clinical-stage biotechnology company specializing in its proprietary Viraltech Architect Platform. Leveraging this platform, the company has built an integrated, end-to-end capability for the development of differentiated biologics. DIFF Biotech has filed over 70 domestic and international invention patents, including more than 10 PCT applications, and has received multiple honors such as the 23rd China Excellent Patent Award, “High-tech Enterprise” and “Quasi-Unicorn” enterprise.

The company’s R&D efforts span mucosal vaccines, antiviral drugs, oncolytic viruses, and gene therapy products. Its vaccine pipeline—powered by proprietary attenuation technologies—effectively establishes the body’s first line of defense at the mucosal barrier, offering clear competitive differentiation. In the oncolytic virus and gene therapy domains, DIFF Biotech has built distinctive capabilities in vector targeting, controllable replication, and high-efficiency gene delivery, enabling the development of advanced, next-generation biologics.

 For more information, please visit https://en.diff-biotech.com/.

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SOURCE DIFF Biotech