Explaining the difference between its candidate and the mRNA-based candidates of Pfizer-BioNTech and Moderna, Tübingen-based Curevac -- the second German player to develop a Covid vaccine -- said it chose to use the potency of untranslated regions to optimize the RNA rather than make chemical modifications.

According to Curevac, its approach has created a candidate that triggers immune responses at a 12-µg dose, compared to the 100 µg used by Moderna. This will enable it to make more doses, the company said, adding that it also aims to “trigger balanced immune responses.”

The Phase 2b part of the clinical trial will randomize 4,000 subjects across two age cohorts, 18 to 60 years and 61 years and older— around 800 to 1,000 of the participants will be in the latter category. Each volunteer will receive two doses of CVnCoV or a placebo four weeks apart.

The aim of Phase 2b is to generate safety, reactogenicity and immunogenicity data to inform the start of Phase 3. When 1,000 volunteers have at least one week of follow-up after vaccination, the Data and Safety Monitoring Board will review the data and make a decision on the studies progressing to Phase 3. CureVac plans to recruit 32,500 subjects for Phase 3 and will pool data from the two parts to draw the correct conclusions.

The first interim review will take place when 56 participants have developed Covid-19,  expected  at around five months after the first vaccination. Later reviews are to be scheduled when the threshold moves to 111 and 185 case. If seven cases or fewer are registered at the time of the first review, however, the company is expected to proceed toward regulatory approval.

In a statement, CureVac CEO Franz-Werner Haas said, “the clinical safety and immunogenicity data achieved to date look promising and we are hopeful that this trial will continue to demonstrate the impact of mRNA technology and our vaccine to prevent COVID-19 and to help defeat this pandemic.”

Author: Dede Williams, Freelance Journalist