German biotech CureVac's stock plunges 50% after its COVID-19 vaccine candidate failed a clinical trial

• CureVac lost more than half its value after its COVID-19 vaccine jab showed 47% effectiveness.
• Results were based on clinical trials conducted in Latin America and Europe on about 40,000 volunteers.
• The company attributed its results to 29 virus strains in the 10 countries where its trials took place.

CureVac's shares tumbled by as much as 50% on Thursday after the German pharmaceutical firm said its COVID-19 vaccine candidate failed in a clinical trial.

Interim analysis of data from about 40,000 volunteers showed the biotech's jab is only 47% effective, falling short of the study's criteria and the minimum 50% effectiveness threshold required by US regulators.

Data for the late-stage clinical trials that were conducted in Latin America and Europe was released after the US close on Wednesday. The company, backed by the Bill & Melinda Gates Foundation, attributed its disappointing results to the fact there are at least 29 COVID-19 strains circulating in the 10 countries where its trials took place.

The Gates foundation owns about 1.7% of CureVac, or 3.1 million shares, according to Bloomberg.

CureVac's US shares are listed on the Nasdaq and plunged after hours from $94.79 at Wednesday's close to $49.54 at Thursday's market open.

The 47% efficacy estimate is based on 134 COVID-cases that occurred at least two weeks after the administration of the second dose, the company said in a statement.

"While we were hoping for a stronger interim outcome, we recognize that demonstrating high efficacy in this unprecedented broad diversity of variants is challenging," CureVac CEO Franz-Werner Haas said.

CureVac said last year that it was working with Tesla on a vaccine printer, which Elon Musk reportedly called "an important product for the world." Musk said in a tweet about the biotech in April that it "sounds like they're a few months away from regulatory approval." This tweet was later deleted.

The company will continue trials of its two-dose messenger RNA vaccine and expects to publish final analysis within the next few weeks.

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