During an informal Zoom chat between Cambridge academics earlier this week, a question was put to an eminent scientist: “What do you think of the idea of giving an Oxford-AstraZeneca vaccine followed by the Russian Sputnik?”

So far the conventional wisdom in the UK and in the west in general has been that that the first and second doses should come from the same vaccine. In other words, no mix-and-match. If someone has been given the Oxford vaccine as a first dose, the second should be the same. That would also apply to the Pfizer-BioNTech vaccine.

But the scientist, who seemed to know what he was talking about, took everyone by surprise with his enthusiastic endorsement of mix-and-match: “I think it’s a great idea.”

Not wishing to take his word for it, The Telegraph approached recently retired Royal Society president Venkatraman Ramakrishnan, who got his 2009 Chemistry Nobel Prize, after all, for his breakthrough on ribosomes.

Venki, too, is onside with mix-and-match: “I think the mixing might be a good idea to eliminate the problem of the vector being recognised in the booster shot, but they need to do some trials, which I believe are under way.”

Hardly had he spoken that the British government announced that mix-and-match trials have started, involving the Oxford/AstraZeneca and the Pfizer/BioNTech vaccines.

The logic seems to be that while two doses of the same vaccine are very good, two doses from different vaccines might be even better and provide longer immunity. For the time being, the British government is sticking to the same vaccine policy but depending on the trial results, this might change in the future.

Some 800 patients from London, Oxford, Southampton, Birmingham, Bristol, Nottingham and Liverpool are taking part in the 13-month study that is being controlled by the department for health and social care.

Speaking for the government, which is ploughing £7 million into the experiment, minister for Covid-19 vaccine deployment, Nadhim Zahawi, said: “This is a hugely important clinical trial that will provide us with more vital evidence on the safety of these vaccines when used in different ways.

“Nothing will be approved for use more widely than the study, or as part of our vaccine deployment programme, until researchers and the regulator are confident the approach is safe and effective.”

He could not resist a bit of flag flying though it is true the UK is far ahead of the EU on vaccine deployment: “This is another great step forward for British science, expertise and innovation, backed by government funding — and I look forward to seeing what it produces.”