CureVac mRNA vaccine only 47% effective

CureVac has announced results of the second interim analysis of its international pivotal Phase IIb/III study in approximatively 40,000 subjects (the HERALD study) of CureVac’s first-generation Covid-19 vaccine candidate, CVnCoV. At second interim analysis, statistical success criteria were not met.

In the unprecedented context of at least 13 variants circulating within the study population subset assessed at this interim analysis, CVnCoV demonstrated an interim vaccine efficacy of 47% against Covid-19 disease of any severity and did not meet prespecified statistical success criteria. Initial analyses suggest age and strain dependent efficacy. Available data were communicated with the European Medicines Agency (EMA). The Data Safety Monitoring Board (DSMB) confirmed a favourable safety profile for CVnCoV. The study is continuing to the final analysis and the totality of the data will be assessed for the most appropriate regulatory pathway.

In total, 134 Covid-19 cases were assessed in this interim analysis. Out of these cases, 124 were sequenced to identify the variant causing the infection. The outcome confirms that only one single case was attributable to the original SARS-CoV-2 virus. More than half of the cases (57%) were caused by Variants of Concern. Most of the remaining cases were caused by other less characterised variants such as Lambda or C.37, first identified in Peru (21%) and B.1.621, first identified in Colombia (7%). In this context, the interim results suggest efficacy in younger participants but did not allow to conclude on efficacy in the age group above 60.

“While we were hoping for a stronger interim outcome, we recognise that demonstrating high efficacy in this unprecedented broad diversity of variants is challenging. As we are continuing toward the final analysis with a minimum of 80 additional cases, the overall vaccine efficacy may change,” said Dr. Franz-Werner Haas, Chief Executive Officer of CureVac. “In addition, the variant-rich environment underlines the importance of developing next-generation vaccines as new virus variants continue to emerge.”

The HERALD study, conducted by Curevac in conjunction with Bayer, enrolled approximately 40,000 participants in ten countries in Latin America and Europe. The second interim analysis included 134 cases, occurring at least two weeks after administration of the second dose. To identify strains causing Covid-19 infections within the trial, sequencing of virus variants has so far been performed on 474 Covid-19 cases, of which 124 fulfilled adjudication criteria and were included in the present efficacy analysis.

Image credit: Spencer Davis

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