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Reasons for the low protection of CureVac mRNA COVID-19 vaccine
Reasons for the low protection of CureVac mRNA COVID-19 vaccine. On June 16, 2021, German mRNA vaccine company CureVac announced that its mRNA vaccine phase 2b/3 clinical trial HERALD study showed that the CVnCoV COVID-19 vaccine has only 47% protection against COVID-19.
This is also the lowest protection among vaccines that have completed clinical trials.
The result immediately attracted widespread media attention and reports, because it was another major blow to the European Union and developing countries’ vaccine supply.
There have been many discussions on mRNA vaccines in the medical community.
The performance of CureVac in clinical trials is determined by multiple factors, and the prevalence of mutant strains in clinical trials is an important factor.
However, as a vaccine that uses the S-2P antigen in the same way as Pfizer and Moderna vaccines, how to modify the mRNA itself becomes critical. The modification of mRNA determines the tropism of DC cells and the signal pathway induced to make it cleared by the innate immune system or express protein.
CureVac uses unmodified mRNA vectors, and I often say that Pfizer and Moderna have extended 3’Poly(A) and modified mRNA with m1Ψ; these modifications not only determine the stability of the mRNA vector, but also determine its DC tropism and induced signals path. If the mRNA vector itself activates a strong TLR/RIG-I signal, its role is not a vector but an adjuvant, so a large number of vectors may be eliminated by the cell before expression.
On June 16, the German biotechnology company CureVac announced that the interim analysis of its candidate COVID-19 vaccine phase III clinical trial showed that the initial effectiveness of the vaccine in preventing COVID-19 diseases was only 47%, and it failed to meet the statistics of at least 50% of the approval requirements. the goal.
After the news was disclosed, the share price of CureVac, which is listed in the United States, fell by more than half. Previously, the EU ordered 405 million doses due to the fact that CureVac’s vaccines do not require ultra-low temperature refrigeration and are lower in cost.
For more than a year, in the fiercely competitive international COVID-19 vaccine competition, CureVac has been regarded as one of the hopes for the successful development of the first batch of COVID-19 vaccines. To eliminate the threat of being acquired overseas, the German government invested 300 million euros in June 2020 to support its development of a COVID-19 vaccine and obtained a 23% stake in the company. However, with a large number of competitors successfully completing clinical trials and being approved for listing, the Tubingen-based company continues to collect data, delaying the estimated approval time again and again.
At the beginning of June, German Health Minister Spahn said that due to problems with the number of participants in the final clinical study, the CureVac vaccine may not be approved by the EMA before August. On the evening of June 16, CureVac issued an announcement stating that the interim analysis of the Phase III clinical trial of its candidate COVID-19 vaccine showed that the initial effectiveness of the vaccine in preventing COVID-19 diseases was only 47%, and it failed to meet the statistics of at least 50% of the approval requirements. the goal.
CureVac said that this phase 2B/3 trial recruited about 40,000 volunteers from South America and Europe. There were 134 cases in the second interim analysis, and the analysis time was at least 2 weeks after the two doses of vaccine were injected. Virus sequencing of 124 of the 134 cases found that only one of the strains was the original new coronavirus strain, and more than 57% of the cases were caused by mutant strains of concern. At least 13 mutated strains are spreading in each research subgroup. In this context, CureVac’s vaccine shows an effectiveness of 47% against all levels of COVID-19 pneumonia disease, which does not meet the pre-set statistical success criteria.
Dr. Franz-Werner Haas, CEO of CureVac, said: “Although we hope to have better mid-term results, we realize that it is very challenging for vaccines to demonstrate efficiency in this unprecedented wide range of variations. We are continuing the final analysis of at least 80 additional cases, and the overall efficacy of the vaccine may change.” At present, CureVac has submitted existing data to the European Medicines Agency (EMA) for analysis and evaluation to determine the most Appropriate regulatory channels.
At present, the hope of meeting the huge demand of the world through this vaccine has become slim. This setback also cast a shadow on the market’s popular mRNA vaccine technology. It uses facts to remind people once again that the safety and effectiveness of the new coronavirus vaccine must withstand the severe test of phase three clinical trials and the mutation of the new coronavirus.
(source:internet, reference only)