“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,” the company wrote in a statement posted Wednesday.
The low efficacy comes in contrast to Pfizer and Moderna’s mRNA COVID-19 vaccines with over 90% efficacy and only somewhat diminished protection in the face of viral variants.
CureVac said 134 COVID-19 cases were identified in the interim analysis, occurring at least two weeks post-second dose, with variants blamed for 124 cases, and just one case was attributed to the original virus. The study involved approximately 40,000 participants across 10 countries in Latin America and Europe.
“While we were hoping for a stronger interim outcome, we recognize 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,” Dr. Franz-Werner Haas, CEO of CureVac, said in a statement. “In addition, the variant-rich environment underlines the importance of developing next-generation vaccines as new virus variants continue to emerge.”
However, the German health ministry said the study’s shortcomings will not impact the speed of the country’s vaccination rollout, Reuters reported. A lead scientist on the study, Peter Kremsner from the University Hospital in Tuebingen, told Reuters he suspects the vaccine’s low dosage contributed to the less-than-hoped for efficacy. Kremsner told the outlet the low efficacy is “very likely due to the dose”.
CureVac didn’t modify the mRNA in the shot, unlike Pfizer and Moderna, and couldn’t achieve a higher dosage due to expected side effects, he said.
“We believe the resulting multi-variant study represents to date, presented today, provides important insights into [a] dramatically transformed variant environment, suggesting that we are virtually fighting a different virus and a different pandemic over the last six months,” the CEO said over a conference call on Thursday.
European governments were aiming to add the vaccine to their stockpile of jabs against COVID-19 after age restrictions were placed on Johnson & Johnson and AstraZeneca’s vaccine amid a tie to rare but serious blood clotting.