A volunteer receives a dose of vaccine or a placebo as part of a testing for a new vaccine against the coronavirus disease (COVID-19), in Brussels, Belgium Photograph:( Reuters )
The stakes for CureVac and prospective buyers of its vaccine in Europe had risen after age limits were imposed on the use of the Johnson & Johnson and AstraZeneca vaccines due to a link to extremely rare but potentially fatal clotting disorders
German biotech company CureVac said on Wednesday its COVID-19 vaccine was only 48 per cent effective in the final trial, missing the study's main goal and throwing in doubt the potential delivery of hundreds of millions of doses to the European Union.
The company in part blamed "the unprecedented context of 15 strains circulating" among the trial volunteers, as well as varying responses across age groups.
The stakes for CureVac and prospective buyers of its vaccine in Europe had risen after age limits were imposed on the use of the Johnson & Johnson and AstraZeneca vaccines due to a link to extremely rare but potentially fatal clotting disorders.
CureVac's shot was also expected to help in low and middle-income countries that have lagged far behind richer nations in the global immunisation drive.
As CureVac's only major supply deals, the European Union in November secured up to 405 million doses of the vaccine, of which 180 million are optional. That was followed by a memorandum of understanding with Germany for another 20 million doses.
The Covid vaccines developed by Germany's BioNTech in partnership with US giant Pfizer and by US firm Moderna -- based on the same novel messenger RNA technology -- were approved earlier on in the pandemic after showing around 95 percent efficacy.
Their trials only had to contend with the original strain of the virus. But recent studies indicate that both vaccines also offer strong protection against the newer, more contagious variants.
CureVac said its jab, known as CVnCoV, did slightly better among people aged 18 to 60 than among older ages, with efficacy climbing to 53 percent.
Among that same 18-60 age group, the vaccine offered 100-percent protection against hospitalisation and death.
In a statement, chief executive officer Franz-Werner Haas said "CVnCoV demonstrates a strong public health value" for people aged 18 to 60 "which we believe will be an important contribution to help manage the Covid-19 pandemic and the dynamic variant spread".
The Tuebingen-based company has shared its data with the European Medicines Agency (EMA), which will now decide if the vaccine is good enough to be greenlit.
The European Union has secured up to 405 million doses of the CureVac vaccine should it receive regulatory approval.
Despite being a laggard in the vaccine race, CureVac believes it has advantages over mRNA competitors.
CureVac's product can be stored at standard refrigerator temperature, unlike the first-generation Pfizer and Moderna vaccines which require super-cold freezers.
CureVac's vaccine also requires a lower dosage of just 12 microgrammes, compared to 30 microgrammes for BioNTech and 100 for Moderna, allowing for faster and cheaper mass production.
These factors could possibly give CureVac an edge in poorer or warmer countries.
Scientists have said the weaker-than-hoped results may be down to the lower dosage, or even CureVac's recipe, which unlike its rivals uses an unmodified form of messenger RNA.
The company is already working on a second-generation Covid vaccine for which it has teamed up with pharma giant GSK.
Early results on rats have been promising, it said. Clinical testing on humans is set to begin in the third quarter of 2021.
CureVac was founded in 2000 by mRNA pioneer Ingmar Hoerr and is backed by Dietmar Hopp, the German billionaire behind software behemoth SAP.
The German government last year took a 23-percent stake in CureVac for 300 million euros.
The move came shortly after media reports said then President Donald Trump had sought exclusive US access to any CureVac vaccine, a claim both sides strenuously denied.
(With inputs from agencies)