The European Union’s Covid vaccine rollout has been dealt a blow after the CureVac jab was shown to be only 47 per cent effective.
The German company had struck a preliminary deal to supply the EU with hundreds of millions of doses.
The disappointing clinical trial results fall just below the threshold set out by the World Health Organisation (WHO) for vaccines.
Its efficacy against new variants and more aggressive forms of coronavirus, such as the Indian strain, may be a little lower than that still, reports The Times.
The news will come as a setback to the EU’s inoculation efforts after it had ordered up to 405 million doses of the CureVac vaccine on behalf of its member states.
The UK had also ordered 50 million doses, while Germany had secured an extra 20 million jabs in addition to the 42 million it was due to receive via the EU.
It is understood the German government invested 300 million Euros on a 23 per cent stake in the firm.
All of these purchases were dependent on authorisation by medical regulators and, as that now hangs in the balance, share prices in the company halved overnight.
Franz-Werner Haas, CureVac's chief executive, said the vaccine had worked well in younger recipients and insisted the firm would still file for approval.
He said: “While we were hoping for a stronger interim outcome, we recognise that demonstrating high efficacy in this unprecedented broad diversity of variants is challenging.
“As we are continuing toward the final analysis with a minimum of 80 additional cases, the overall vaccine efficacy may change.”
Despite the disappointment, it is not likely the results will impact on EU’s lamented vaccination programme, which is mostly reliant on the Pfizer-BioNTech jab.
“[These results] will have no effect on the speed of our vaccination campaign,” a spokesman for the German health ministry said.
CureVac's trials involved more than 40,000 people and took place across ten countries in Europe and Latin America.
Tests on 124 patients who became infected showed that just over half of them had picked up “variants of concern” such as the Gamma (Brazilian) and Delta (Indian) variants.
Others, however, had strains that are currently less understood, including the Lambda (Peruvian) and another called B.1.621, first identified in Colombia, making it hard to compare CureVac's efficacy against other vaccines.