The University Oxford is launching a medical trial alternating doses of Covid-19 vaccines created by different makers, the first study of its kind, it said on Thursday.
The trial will show whether different Covid vaccines, created by Astrazeneca and Pfizer/BioNTech, can be used interchangeably to allow greater flexibility in tight vaccine delivery schedules.
The British government's deputy chief medical officer, Prof Jonathan Van-Tam, said the trial would offer "greater insight" into the use of vaccines against Covid.
"Given the inevitable challenges of immunising large numbers of the population against Covid-19 and potential global supply constraints, there are definite advantages to having data that could support a more flexible immunisation programme," Prof Van-Tam said.
"It is also even possible that by combining vaccines the immune response could be enhanced, giving even higher antibody levels that last longer."
The 13-month study will compare different combinations of prime and booster doses of the AstraZeneca and Pfizer-BioNTech vaccines at intervals of four and 12 weeks.
Britain, the first western nation to launch its vaccination programme, bucked the international trend by administering vaccines at an interval of 12 weeks to give a first dose of the vaccine to more people.
Prof Matthew Snape of Oxford called the study "extremely exciting", saying it would provide "information vital to the roll-out of vaccines in the UK and globally".
If the study shows positive results, Britain's independent medicine regulator would formally assess the safety and efficacy of any new vaccination regimen before it is given to patients.
Disagreements between the UK and the EU over vaccine supplies boiled over in recent weeks, with Brussels moving to restrict exports to Northern Ireland on Thursday before the plans were quickly abandoned.
In the following days, EU member states and the European Commission continued to criticise English-Swedish drug maker AstraZeneca over slow delivery while the efficacy of the vaccine was also called into question.
On Wednesday, the British government seized on a separate study that said the AstraZeneca vaccine significantly reduced virus transmission and was highly protective after a single dose.
AstraZeneca and Oxford said on Wednesday that vaccines against new developing coronavirus variants should be ready by October.
