Rocketvax Achieves Major Breakthrough in Live-Attenuated SARS-CoV-2 Vaccine Development

The preclinical data were published on 23 May 2025 in npj Vaccines, published by Nature Portfolio, in an article titled “Live attenuated SARS-CoV-2 vaccine OTS-228 demonstrates efficacy, safety, and stability in preclinical model.”

Key Findings:

• OTS-228 shows excellent safety and high efficacy in Syrian hamster models.
• Maximum dose trials confirm full attenuation and prevention of virus spread.
• Serial in vivo passages reveal no reversion to virulence and high genomic stability.
• Maintains efficacy and attenuation even after 15 in vitro passages.
• Protective dose 50 (PD₅₀) established at <100 TCID₅₀ per hamster in low-dose challenge infection.

The vaccine was scientifically conceived and designed by Professor Dr. Volker Thiel, one of the world’s leading coronavirus researchers:

“OTS-228 is the result of years of coronavirus research and rational vaccine design,” said Professor Thiel. “Live-attenuated vaccines can offer long-lasting and broad immunity, and our data show that OTS-228 has the potential to become a safe and effective tool against current and future SARS-CoV-2 variants.”

The preclinical studies were conducted at the Friedrich-Loeffler-Institut under the direction of Professor Dr. Martin Beer, Director of the Institute of Diagnostic Virology. 

Leading the partnership efforts, Dr. Natasa Cmiljanovic, Chief Operating Officer of Rocketvax, added:

“This successful collaboration with the University of Bern and the Friedrich-Loeffler-Institut has been pivotal. The robust preclinical results validate our live-attenuated vaccine platform and position Rocketvax to advance into clinical development. We are committed to making this innovative vaccine available as a global public health solution.”

In addition, Rocketvax has entered a strategic partnership with Emergent BioSolutions, a publicly traded U.S. biotech company, to commercialize Rocketvax vaccines in the U.S. The alliance leverages Emergent’s manufacturing infrastructure and regulatory experience to accelerate worldwide access to Rocketvax’s COVID-19 vaccine platform.Rocketvax is making significant progress in the development of its lead candidate and is preparing for the regulatory submissions to launch first-in-human clinical trials. Discussions with investors, public health agencies, and strategic partners are actively underway to support the next development phase.