why the CureVac vaccine was 47% effective, according to the laboratory

German vaccine CureVac, which has been tested in Argentina, has shown efficacy of only 47% against the coronavirus. Although these are “preliminary results”, it is well below the efficiency rates of its direct competitors: Pfizer Yes Modern, which are also based on messenger RNA technology and greater than 90%.

The German laboratory justified the results, “not expected”, mainly, by the new variants. “In fact, we are fighting another virus», Declared this Thursday the executive director Franz-Werner Haas, during a virtual press conference in which he participated Bugle.

“Over the past 6 months, and in an increasingly difficult environment with new variants, we conducted a pivotal phase 3 efficacy trial with our vaccine. This study is unmatched in terms of geographic diversity, as it is conducted in 10 countries in Europe and Latin America“, He maintained. Thus, he separated himself from the competition.

The first analyzes of CureVac suggest an effectiveness dependent on the strain and the age. “Although we expected a stronger result from the second preliminary scan, we saw trends that indicate effectiveness in the younger age groups, under 60 years, as well as a potentially differentiated efficiency by strain. “

In two or three weeks will be the results of the second stage, which would make it possible to have determinations on effectiveness according to strains and ages. Specifically, in terms of age group, examine the efficacy reported in participants under the age of 60.

“The final analysis will be based on more than 200 cases, to confirm trends related to age and exertion, and also to examine the severity of illness“continued the expert.

The low efficiency of CureVac was highlighted in a preliminary analysis based on 134 cases of Covid-19, in a study with around 40,000 volunteers in Europe and Latin America, including Argentina. It all lasted 6 months.

The vaccine “with a high proportion of mild cases (80%), it had a preliminary efficacy of 47% (against Covid-19 disease of any severity) and did not meet the previously specified statistical success criteria, ”they said from the CureVac laboratory, which signed a major ordering contract with the European Union.

According to CureVac, at least 13 viral variants they are responsible for the contagions produced within the population studied. Of the Covid-19 cases reported in the test, 124 were sequenced to identify the variant causing the infection.

“Only one case corresponds to the original version of the coronavirus (the one that emerged in the Chinese city of Wuhan at the end of 2019), while 57% of cases were caused by highly transmissible variants (variants of interest), ”they detailed in the exhibition before world media.

The EU has obtained up to 405 million doses, of which 180 million “are optional”. There is also a memorandum of understanding with Germany for an additional 20 million doses. By not achieving the objective, he obtains doubts its supply in Europe. Argentina had not yet acquired these vaccines.

Low efficiency and new context

The German laboratory focuses on this phase 3 of your vaccine is very different in phase 3 during which the other vaccines proved to be highly effective. For this circulation of so many variants. So Pfizer, Sputnik V or AstraZeneca, in today’s world, outside of testing, are they also less effective?

For Javier Farina, infectologist from the Argentine Society of Infectology (SADI), the relation is not so linear. “In the northern hemisphere, when these first vaccines (Pfizer and Moderna) were tested for the first time, there was little or no circulation of variants (including Delta),” he explains to Bugle.

And he adds: “Now, in the trial period of CureVac, there is high circulation Delta. But the CureVac study went wrong, otherwise they wouldn’t have placed so much emphasis on the new variants. “

The “non-linearity” of the conclusions lies, according to Farina, in the fact that the only observation of changes in the efficacy of vaccines already tested dates from a report from England and Scotland “Where a 10 to 15% decrease in the overall effectiveness of the vaccines used, whether Pfizer or AstraZeneca, has been observed. This is in real life, not in the Phase 3 study.

Are there any sudden changes in the efficacy result of CureVac expected after the final tests are completed? “Overall, between the preliminary and advanced results of other vaccines there were no big changes. And I understand that in this aspect this CureVac brand either. In addition, age has not yet been shown to be a determinant of efficacy. At the moment, it is not a vaccine that can be recommended or approved“, replies Farina.

Eduardo López, renowned infectious disease specialist and government adviser on health issues, marks a Bugle that the bar is high in the world of vaccines – with which they go 70% to more than 90% efficient-, but there is also a base, an “approved”. And that CureVac does not happen.

“The World Health Organization (WHO) only approves vaccines that show from 50% efficiency. This one did not succeed. It’s right on the edge. We’ll have to see if that happens, “he said. Why is the justification so based on variants?” I don’t know why CureVac failed, yet the data is poor “Lopez said.

“The analyzes which were carried out in the serum of vaccinated Pfizer or AstraZeneca show the ability to neutralize new strains, although with a lower degree of efficiency, but not much different. Not ‘critical’ efficiency, as is the case with CureVac, ”he adds.

In any case, as all vaccines have small or large differences (the same platforms, like messenger RNA, also have their peculiarities), the two experts give The benefit of the doubt. Must wait.

MG