The rapid development of messenger DNA vaccines (m), such as the immunizing agents of Pfizer and Modern, raised expectations regarding this technology. However, the CureVac vaccine has shown that not every mRNA project will live up to the expectations employed upon them and, unfortunately, some will end up showing weaker results.

In the case of the German biotechnology company, in addition to the proliferation of virus variants, some crucial choices differentiate its candidate's results when compared to projects that achieved even 90% effectiveness, although the results of different immunizations are not comparable with each other. One of those elements was the dosage, CureVac executives said they probably weren't using enough mRNA to induce strong immunity.


The low dosage was necessary as the company was using a different type of mRNA than those used by Pfizer and Moderna. This choice was made because larger amounts could increase the risk of side effects in the volunteers. Thus, the result of the vaccine was only 47% effective against Covid-19 infections.

CureVac's candidate used less mRNA than Pfizer and Moderna. Credit: Thodonal88/Shutterstock

Let's take it easy

Despite the weak results, it is too early to call CureVac a failure, however, preliminary results below the average put the choices made by the company in check, suggesting that virus variants may not be solely responsible for the poor performance of the vaccine in these tests.

If CureVac does not get the approval of health surveillance agencies for its first-generation vaccine, conducting clinical trials for a more promising second-generation version of the vaccine will be hampered. This second version would be more powerful, even without involving the modification of the mRNA, but by optimizing the formula.

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"There was room for improvement for the technology" in the context of developing a second-generation dose of Covid, CureVac spokeswoman Sarah Fakih told Bloomberg. “We could also discuss whether he was the best candidate. But the results do not have a reading of the technology that is not working”, continued the advisor.

However, if improved, CureVac's approach could have advantages over immunizers from Pfizer and Moderna, as it leaves the mRNA in a more natural state, while its competitors use chemical compounds to “mask” their products. Despite the setback, CureVac says it will continue the development of its immunizer and will seek regulatory approval, as, they say, more vaccines are needed.

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