The Phase 1 dose-finding study (ORFEUS) will assess the safety, tolerability and immunogenicity of a two-dose regimen (28-days apart) of PRIME-2-CoV_Beta administered by intramuscular (IM) route in adult participants.~In the first part, the safety and immunogenicity of increasing doses of PRIME-2-CoV_Beta will be assessed in adult healthy participants aged 18 to 55 years who have been vaccinated against COVID-19 with at least two doses of a SARS-CoV-2 mRNA vaccine (i.e. primary sequence with or without booster vaccination, subsequently referred to as pre-vaccinated). In addition, one dose level which has been identified as optimal will be assessed in a small cohort (12 participants) of participants 18 to 55 years of age who are SARS-CoV-2 vaccine-naïve.~In addition, three dose levels identified in pre-vaccinated participants will be further evaluated for safety and immunogenicity in pre-vaccinated elderly participants aged 65-85 years (B-cohorts).
PRIME-2-CoV_Beta is the first clinical candidate based on the attenuated 2nd generation Orf virus (ORFV) vaccine platform which encodes for the structural spike (S)- and nucleocapsid (N) protein of SARS-CoV-2. The aim of the multivalent vaccine is to broaden the specific immune response against SARS-CoV-2 and to increase the probability of cross-protection against emerging variants.