A coronavirus vaccine manufactured by German company CureVac was only 47 percent effective in interim results, the company announced Wednesday, a major setback that was due largely to the difficulties posed by new variants.
The company’s 40,000 person trial was conducted in 10 countries in Latin America and Europe, where “at least” 13 different variants were circulating. The 47 percent efficacy result, while not final, is the lowest reported to date from any COVID-19 vaccine manufacturer.
“While we were hoping for a stronger interim outcome, we recognize that demonstrating high efficacy in this unprecedented broad diversity of variants is challenging,” Franz-Werner Haas, CureVac’s CEO, 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.”
The company did not disclose many more details about the study, but said the trial would continue, with final results coming in two to three weeks.
The trial results released Wednesday were based on data from 134 people who became infected with COVID-19. Sequencing of the viruses showed that only one single case was attributable to the original SARS-CoV-2 virus. More than half of the cases were caused by “variants of concern.”
The vaccines currently available in the U.S. were all tested prior to the emergence of new variants of the virus. However, real-world data suggests that even when variants are flourishing, the vaccines remain strongly effective, and prevent severe hospitalization or death.
The company said it submitted data to the European Medicines Agency. The European Union reached an agreement last year to purchase up to 225 million doses of the vaccine, with an option for an additional purchase of 180 million doses.
CureVac is backed by the Bill & Melinda Gates Foundation, which invested $52 million. Its vaccine relies on mRNA technology, similar to what is used in the successful Pfizer-BioNTech and Moderna vaccines.
However, the CureVac vaccine uses mRNA that is not chemically modified and it is stable at normal refrigerator temperature, eliminating the complicated cold-storage requirements of the other mRNA vaccines and making it easier to ship and store.
It’s also cheaper to manufacture, which makes it attractive to low- and middle-income countries that have been struggling to obtain much-needed doses. However, the new results could make it difficult for the company to get approval even in developing countries.