trial, which included 40,000 volunteers in Latin America and Europe, estimated the efficacy of CureVac’s mRNA vaccine was only 47 percent, the lowest ever reported from any COVID-19 vaccine manufacturer. Trials will continue as researchers monitor volunteers for new cases of COVID-19, with a final analysis expected in two to three weeks.
“We are going full speed for the final readout,” CureVac chief executive Franz-Werner Haas said in an interview. “We are still planning to file for approval.”
The company plans to initially apply for authorization to the European Medicines Agency. The European Union last year struck an agreement to buy 405 million doses of the vaccine if the agency authorizes it.
However, independent experts said it would be difficult for CureVac to recover. Natalie Dean, a biostatistician at the University of Florida, said there could be some improvement in the vaccine’s efficacy rate by the end of the trial. But since most of the data is already in place, it is unlikely that the vaccine will become highly protective. “It’s not going to change dramatically,” she said.
And with an efficacy rate that’s less than that of competing mRNA vaccines made by Pfizer—BioNtech and Moderna—about 95 percent—the results don’t bode well for CureVac’s adoption of shots.
“It’s very devastating for them,” said Jacob Kierkegaard, a vaccine supply specialist at the Peterson Institute for International Economics, a think tank in Washington.
The news was disappointing to experts who hoped the company could make vaccines available to low- and middle-income countries, which don’t have nearly enough. CureVac had some advantages over other mRNA vaccines, such as being stable for months in the refrigerator. Furthermore, compared to its competitors, CureVac’s vaccine used fewer mRNA molecules per jab, reducing its cost.
The test results released on Wednesday were based on data from 135 volunteers who became ill with COVID-19. An independent panel compared the number of sick people who had received the vaccine to those who had received a placebo. Although the vaccine appears to provide some protection, the statistical difference between the two groups was unclear, operating at an efficacy rate of 47 percent.
annual Flu Vaccine, by comparison, can reach 40 to 60 percent effectiveness. Both the World Health Organization and the Food and Drug Administration have set a 50 percent efficacy threshold for emergency authorization to consider COVID-19 vaccines. If CureVac were to remain at 47 percent in the final analysis, it would have failed to meet that standard.
The results surprised the scientists. The vaccine is made from engineered mRNA, the same technology used in Pfizer-BioNtech and Moderna Vaccines. And shots of CureVac yielded promising results in animal experiments and preliminary clinical trials.
“It’s a head-scratcher,” Dr. Dean said.
Dr. Haas attributed the disappointing results to the high number of virus types in the countries where the vaccine was tested. Of the 124 COVID-19 cases genetically sequenced by the company’s scientists, only one was caused by the original version of the coronavirus.
More than half of cases are due to forms that have been shown to be more permeable or capable of blunting the effectiveness of vaccines. CureVac volunteers were also infected with variants that have yet to be carefully studied. lambda, which has dominated Peru in recent weeks, accounted for 21 percent of samples.
Dr Haas said the results should serve as a warning to the danger that new variants may pose to the effectiveness of vaccines. CureVac is exploring new RNA molecules that can simultaneously work against multiple variants, as well as combining RNA molecules corresponding to different variants in a single dose. “This is a new Covid reality, that’s for sure,” he said.
Moderna and Pfizer-BioNtech were tested last year before the variants emerged, which may partly account for their high efficacy rates. Still, studies have found that their real-world effectiveness drops only marginally in the face of variants. in a study QueueFor example, Pfizer-BioNTech was 87 to 89.5 percent effective against the alpha version previously identified in the UK and 72.1 to 75 percent effective against the beta, which was first detected in South Africa.
Dr. Haas also noted that in preliminary findings, older people seem to have less protection from the vaccine than younger volunteers. “The elderly are not benefiting,” he said. But it’s not clear whether the final results of the trial will allow CureVac to be confident of any differences between the two groups.
Prashant Yadav, a health care supply chain specialist at the Center for Global Development in Washington, said the disappointing results challenge the notion that all mRNA vaccines are the same.
“We have had this question mark since the beginning of research on mRNA vaccines,” he said. It’s possible, Dr. Yadav said, that CureVac’s design may partly account for the low efficacy, not just the variant.
Although many vaccine experts saw promise for shots of CureVac in most of the unconvinced world, the new results bolster their outlook.
Dr. Kierkegaard predicted that it would be a challenge for CureVac to compete with another second-wave COVID-19 vaccine, which was created by novavax. On Monday, Novavax reported that its vaccine, which doesn’t have to be frozen, reached 90 percent efficacy in a trial in the United States and Mexico.
“I suspect that it will be difficult for them to get a really important developing country market,” said Dr. Kierkegaard.