The global Need for a Second-Generation
COVID-19 Vaccine

The protection conferred by current single-antigen expressing COVID-19 vaccines is known to be declining over time. Our approach, which is to combine the expression of Spike and Nucleoprotein into one single vector, aims at triggering a better induction of the cellular arm of immunity, thus extending the duration of the protection conferred by the vaccine. Induction of a strong cellular immunity is also needed to better address the emergence of new SARS-CoV-2 variants.

Pre-existing immunity against the vector is a common issue with vector-based vaccine candidates. Due to the low prevalence and short-lived pre-existing anti-ORFV immunity in humans, Prime-2-CoV-based vaccines are expected to support repeated vaccinations.

ORF Virus Platform as a COVID-19 Vaccine

The Prime-2-CoV vaccine platform was established  at the University of Tübingen, Germany. It is based on a highly attenuated and non-pathogenic live viral vector D1701-VrV derived from an ORF Virus isolate, naturally infecting sheep and cattle. Used for 20 years in biomedical research and veterinary medicine, this vector has highly beneficial characteristics for the development of a COVID-19 vaccine:

  • Very good safety and tolerability profile.
  • Uptake of the vector by antigen-presenting cells resulting in the induction of a strong humoral and cellular immune response directed against the encoded antigens without the need for adjuvants.
  • Development of an immunological memory that provides long-lasting protection against the disease.
  • Repeated vaccinations possible due to weak to absent anti-vector neutralizing antibodies generation upon immunization and the low prevalence of pre-existing immunity against ORFV in the population.
  • Capacity to encode multiple antigens of large size in a single multivalent vaccine.
  • Modular vector design allowing the rapid generation of vaccine prototypes.
  • Cell culture manufacturing for fast and controlled production in existing vaccine production facilities. Ability to scale up production.
  • Promising thermal stability and formulation supporting lyophilization offering technical and logistical advantages.

What makes Prime-2-Cov different


Most of existing COVID-19 vaccines only target a single antigen, the Spike protein of the SARS-CoV-2 virus. Speransa’s multivalent vaccine approach allows for immunization with additional target antigens. In addition to the Spike protein, our second-generation vaccine candidate Prime-2-CoV also expresses the nucleocapsid protein N of SARS-CoV-2, for a broadened immune response against infection, long-lasting immunity and increased protection against new variants.

High stability

Current technologies require challenging cold supply chain logistics preventing a wide, global vaccine distribution. Speransa’s Prime-2-CoV vector platform demonstrates a high thermal stability, even after several weeks of ambient temperature storage.

Scientific Publications about our Technology