Joussen said that should the UK hit its current vaccination targets, it would have an "immediate impact" on Britons’ booking and travel behaviour this summer.

He added the programme had given Tui hope other important European source markets would be able accelerate their programmes in the weeks and months to come.

"Even if there are delays in the first vaccination phase in some European countries, the vaccination campaigns will lead to the restoration of basic freedoms in many areas of life in the coming months," said Joussen.

"The more determinedly the vaccination campaigns are implemented, the faster we can return to true freedom to travel."

However, Joussen said besides vaccination, reliable testing would also play a key role in reopening borders this summer and allowing holidays to go ahead – but stressed it was his belief there were "ways and means"to make travel possible again in the spring.

"In the transition period, rapid tests can play an important role, especially in tourism," said Joussen.

"We should use these opportunities wherever possible for the sake of the many millions of employees in the European tourism sector and the travellers.

"With uniform and reliable regulations on rapid tests, we can leave quarantine obligations and closed borders behind us. Rapid testing instead of quarantine is a demand of the travel industry, to which Tyui also adheres."

Joussen added that vaccination and rapid testing had changed the outlook for travel in summer 2021 significantly compared to summer 2020.