Efforts by the British and French drugmakers to produce a Covid-19 vaccine have suffered a further setback, with final clinical data on the jab and a potential launch delayed until next year, as they struggle to find enough uninfected people to test it on.
The two vaccine specialists announced positive preliminary results from a trial that showed the vaccine raised antibody levels against Covid by nine to 43 times when given as a single booster shot in people who had already received doses of Pfizer/BioNTech vaccines.
An independent review body said there were no safety concerns. It is the most comprehensive booster trial to date.
Initial clinical trials revealed that the vaccine failed to produce a strong immune response in older people, after a dose error. The vaccine's immune response is boosted by the substance that stimulates the immune system to produce antibodies against it.
The jab is being tested on new versions in countries including the US, France and the UK.
More than 10,000 volunteers are involved in separate late-stage trials of its use as a primary vaccine. The two companies said that regulatory authorities require phase III efficacy to be demonstrated in naive populations.
