Berlin (AFP)

It was to be the next anti-Covid vaccine approved in Europe, already pre-ordered in millions of doses by Brussels: lack of sufficient effectiveness, according to provisional data, the future of the product developed by the German laboratory CureVac now appears uncertain .

The first results have a bitter taste for this company recognized as one of the pioneers in messenger RNA technology.

CureVac announced Wednesday evening that its main candidate vaccine against Covid-19 had only shown an efficacy of 47%, according to the interim analysis of a large-scale clinical trial.

At this stage, it does not meet the required performance criteria.

"The final efficacy could still change," warns the CEO of the laboratory, Franz-Werner Haas, quoted in a press release, which notably questions the difficulties posed by the appearance of variants of the coronavirus.

The boss said Thursday during a conference call that CureVac had to face "a different virus" because of the "great diversity of mutations" present when he began this phase of testing in December.

- "We continue" -

The company was among the first to enter the vaccine race and was still hoping to bring a high-performance serum to market in May, or June of this year at the latest.

If the immune response of the product is not significantly improved, marketing seems unlikely, according to experts.

A continuous review procedure is underway with the European Medicines Agency (EMA).

Marco Cavaleri, head of vaccine strategy at the agency, on Thursday called for caution: even if the required threshold of 50% efficacy is not met, "this does not mean that we will not examine the data set. We will consider the benefits and risks demonstrated by the vaccine "to make a decision on its approval.

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The boss of the laboratory told him to continue "at full speed" development, "until a final evaluation" expected in two to three weeks.

He suggested that the final product could possibly serve as a "booster" for the first two injections of another preparation if its own efficacy was insufficient.

The BioNTech / Pfizer and Moderna vaccines, also based on the principle of messenger RNA, have demonstrated an efficacy of approximately 95%.

That of the AstraZeneca and Johnson and Johnson vaccines is between 60 and 70%.

CureVac is conducting the final phase of its trials on around 40,000 volunteers in Europe and Latin America.

The immune response has been evaluated in 134 cases of patients who contracted Covid and 80 more cases still need to be analyzed.

Of 124 cases sequenced, only one was of the original strain of SARS-CoV-2, while "more than half of the cases (57%)" were caused by variants considered of concern by the World Health Organization. (WHO), CureVac note.

But the progression of variants is not the only cause in this setback, according to experts who recall that the products of BioNTech and Moderna have demonstrated some effectiveness in the face of coronavirus mutations.

The formulation chosen by CureVac, especially its lower strength of 12 micrograms, could be a factor.

- Public support -

The European Commission has signed a contract with the Tübingen biotech (southern Germany) for the purchase of 405 million doses.

The laboratory's announcement has "no impact on the pace of our vaccination campaign," commented the German Ministry of Health.

The effect, however, was massive on the price of the company, listed in New York, which collapsed by nearly 50% when trade opened.

Founded in 2000, CureVac's main shareholder is German billionaire Dietmar Hopp, co-founder of software giant SAP.

In June 2020, the German government had taken a stake of 300 million euros to acquire 23% of the shares of the laboratory, after an attempt by the American authorities to obtain exclusive rights for the United States on a potential vaccine of CureVac.

The company has joined forces with Swiss pharmaceutical giants Novartis and German Bayer for the production phases.

Allied to the British GSK, it is developing in parallel so-called second generation vaccines, taking into account the variants, but whose development is less advanced.

© 2021 AFP