LONDON: There is a growing consensus around the world that some form of evidence to prove a traveller is free of COVID-19 might be useful to see more people return to air travel, Prime Minister Boris Johnson said on Wednesday.

"There's no doubt that there's a growing global consensus that for the purposes of aviation that evidence of vaccination, or immunity that you've had the disease, or you have taken a negative test, all of these will be valuable," he told a parliamentary committee.