But mRNA vaccines should be easier to adapt because they simply deliver genetic codes in tiny bubbles of fat, then use the body as a factory to make the protein the immune system needs to recognise. These codes can be quickly swapped out and there is no need for the enormously time-consuming process of growing cells in tanks that is required for other types of vaccine.

“mRNA should be the easiest: you can get a new cassette and put it in and so if you need it, you should be able to produce a new vaccine,” said Walton…

Pfizer recently said it had cut the time from the start of the process to putting vaccines into vials from 110 days to 31.

While adenovirus vector vaccines such as the Oxford/AstraZeneca and Johnson & Johnson jabs are also fairly easy to adapt, they are far trickier to scale up. Michael Leuchten, a UBS analyst, said this was shown in the struggles AstraZeneca had with production earlier this year.

“Adenovirus vectors do not like scaling up. They take personal offence to that,” he said.