Nano Messenger Biotech Co., Ltd., a Shanghai-based biotechnology company fully acquired by Kanghua Bio (300841) in April 2026, initiated a Phase II clinical trial for its freeze-dried respiratory syncytial virus (RSV) mRNA vaccine on May 29.
The vaccine, codenamed NR222, is being trialed in Guilin, Guangxi Zhuang Autonomous Region.
NR222 represents the first freeze-dried mRNA RSV vaccine to receive clinical trial approval in China.
This milestone is significant for both mRNA vaccine development and lyophilization technology in the biologics sector.
The trial is designed as a randomized, double-blind, placebo-controlled study scheduled to enroll 375 healthy participants.
It will be conducted under the supervision of the Guangxi Center for Disease Control and Prevention.
NR222 was developed using Nano Messenger‘s proprietary lipid nanoparticle (LNP)-mRNA platform and an AI-assisted sequence optimization platform.
Its unique amino acid sequence design enhances antigen immunogenicity and stability.
The freeze-drying formulation addresses a critical challenge that has long constrained mRNA vaccine deployment: the poor thermal stability of liquid formulations.
The vaccine is expected to remain stable for over 36 months under standard 2°C to 8°C cold chain conditions.
This dramatically improves accessibility compared to the ultra-low temperature requirements that have limited distribution of liquid mRNA vaccines.
Preclinical studies demonstrated that NR222 induces high-titer neutralizing antibodies against both RSV subtypes A and B in mouse and cotton rat models.
It exhibited cross-neutralizing protection potential with no evidence of vaccine-associated enhanced respiratory disease.
A non-clinical head-to-head study showed superior viral suppression effects compared to an already marketed recombinant protein RSV vaccine.
Phase I clinical trials confirmed safety with no vaccine-related serious adverse events, and immunogenicity data supported advancement to the Phase II stage.
RSV is a leading cause of respiratory infection hospitalizations and deaths among infants and the elderly, and currently no effective RSV vaccine is commercially available in China.
