This week, CureVac (NASDAQ:CVAC) shocked investors and scientists alike by announcing a drastically low efficacy rate for its messenger-RNA-based COVID-19 shot from a large global trial.
Compared to the ~95% efficacy rate shown by established mRNA-based vaccines from Pfizer (NYSE:PFE)/ BioNTech (NASDAQ:BNTX) and Moderna (NASDAQ:MRNA), the 47% rate demonstrated by CVnCoV in the interim analysis did not even meet the threshold set by the World Health Organization (WHO).
Pointing out that more than half of the cases sequenced in the study were caused by COVID-19 Variants of Concern, the company blamed the impact of the variants for the below-par efficacy. However, some scientists disagree.
“It’s just hard for me to believe that the variants could have this degree of effect,” Kathleen Neuzil of the University of Maryland School of Medicine told Science arguing that Pfizer-BioNTech and Moderna shots “work very well against Alpha,” the variant first detected in the U.K.
Drew Weissman of the University of Pennsylvania’s Perelman School of Medicine thinks that the design of the vaccine could be to blame. For the vaccine, CureVac has used an unmodified form of mRNA as opposed to the modified mRNA structure used in other mRNA-based COVID-19 shots.
Peter Kremsner of University Hospital Tübingen pointed to the lower dose CureVac had to settle on for late-stage studies.
However, the German biotech has yet to complete the final analysis of the study, and the CEO Franz-Werner Haas remains hopeful over a regulatory nod for the shot. “At the moment we are of course fully committed to obtain authorization, the data will show,” Haas told.