A volunteer receives a dose of CureVac vaccine or a placebo during a study by the German biotech company CureVac as part of a test for a new vaccine against coronavirus disease (COVID-19) in Brussels on March 2, 2021.

Yves Herman | Reuters

CureVac shares plunged 50% in expanded trading on Wednesday after the German biopharmaceutical company released preliminary efficacy results for its Covid-19 vaccine candidate that failed to meet the success criteria.

According to a press release, the vaccine candidate has since shown an effectiveness of 47 percent against Covid 19 disease of “any severity”. The company said final analysis of the results will be completed in the coming weeks.

The late-stage clinical study with around 40,000 participants from 10 countries revealed a high prevalence of virus variants, particularly the lambda strain first discovered in South America.

“Although we had hoped for a stronger interim result, we know that it is a challenge to show a high level of effectiveness in this unprecedented variety of variants,” said CEO Franz-Werner Haas in a statement. “As we are heading towards the final analysis with at least 80 additional cases, the overall effectiveness of the vaccine may change.”

The study also found different levels of effectiveness for different age groups, depending on the publication.

CureVac is also working in partnership with GlaxoSmithKline on a separate Covid vaccine candidate. The companies expect to enter clinical trials with this candidate in the third quarter of 2021, CureVac announced on Wednesday.