Earlier this month, England's deputy chief medical officer, Jonathan Van-Tam, said the modelling is "getting more difficult to give us any clear sense of whether things will turn up or down."

"We're in for potentially some difficult months over the winter," he told reporters.

However, British Prime Minister Boris Johnson said earlier this week that there is "nothing in the data saying we need to move to Plan B" in Britain.

"The best single thing you can all do is get your booster. When you are called forward to get it, please do so," Johnson said to reporters after his speech at the Confederation of British Industry (CBI) annual conference.