Germany’s CureVac jab shows only 48% effectiveness against Covid-19 in final stage of trial, driving stock plunge

German biotech firm CureVac said its coronavirus vaccine showed just 48% efficacy against Covid-19 following its final analysis, marking only a slight improvement on the company’s last trial while sending its stock value tumbling.

CureVac announced the second- and third-phase trial results for its CVnCoV vaccine on Wednesday, in its final analysis for a 40,000-subject study that drew participants from 10 countries across Europe and Latin America. 

“In the unprecedented context of 15 strains circulating within the study population at the time of final analysis, CVnCoV demonstrated an overall vaccine efficacy of 48%... against Covid-19 disease of any severity, including single non-respiratory mild symptoms,” the company said, adding that the 18-60 age group fared slightly better, at 53%.

The results were only a meager improvement over CureVac’s preliminary trial earlier this month, which showed the vaccine had 47% overall efficacy.

While CureVac noted that the inoculation was even more effective against “moderate to severe disease” in the 18-60 age group, reporting the figure at 77%, the data was inconclusive for older patients, who face significantly greater risk from Covid-19. Those aged 60 and older represented just 9% of the analyzed cases, but the firm said the available data “did not enable a statistically significant determination of efficacy.”

For severe disease that results in hospitalization or death, the company said its vaccine was fully effective for those aged 18 to 60.

The news dealt a blow to CureVac’s stock value, which initially plunged by some 10 points in after-hours trading, beating back a 9% gain seen earlier on Wednesday after the company announced a reshuffling of its board. CureVac’s previous disappointing trial results had a similar effect on the market, with Wednesday’s data further dashing confidence in a vaccine once forecasted to “bring hope to the unvaccinated world.”

Despite the poor showing, CureVac CEO Franz-Werner Haas spoke optimistically about the vaccine, saying the latest analysis “demonstrates a strong public health value” for the 18-60 age group and provides “clinically relevant data” for emerging coronavirus variants.

The CVnCoV vaccine uses messenger RNA technology similar to the more effective Moderna and Pfizer shots, however unlike those immunizations, CureVac’s remains stable at refrigerator temperatures and does not require sub-zero storage. Russia’s Sputnik V also needs no special storage, making such vaccines attractive for developing nations that lack deep freeze facilities.

Though the World Health Organization recommends an efficacy threshold of at least 50% for coronavirus vaccine trials, the European Union’s drugs regulator suggested last week that it would not impose a similar requirement. Asked about a 50% threshold following CureVac’s preliminary trial results, the agency’s vaccine chief Marco Cavaleri said the regulator “always felt it was difficult to define upfront a threshold.”

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