The boss of one of the companies leading the race for a coronavirus vaccine has suggested that normality could resume in the second half of 2021.
Albert Bourla, chief executive of US pharmaceutical firm Pfizer, said that if his company's jab was successful, normal life would return.
Earlier this week Pfizer revealed that final results from the late-stage trial of its vaccine show it is 95% effective.
The vaccine has been developed with German partner BioNTech.
Speaking to Sky News Mr Bourla said: "As things (are) going on, until we reach herd immunity, people need to be very careful.
"They need to wear a mask, social distance.
"There is light at the end of the tunnel, it's real. We never believed to have a vaccine of this efficiency so people need to be patient.
"I believe that the second half of 2021 will be a very different experience for a lot of us.
"I think if we will be able to vaccinate, we can go back to normal life."
Mr Bourla said that his company had already produced 20 million doses of the vaccine and were preparing for distribution as soon as global regulatory authorities gave permission.
He said that submissions to regulators would be made within several days and that shipping would begin "a couple of hours" after being given the green light.
The UK has secured 40 million doses in total of the vaccine, with 10 million due in the country by the end of the year if the vaccine is approved.
Mr Bourla added that although Britain's exit from the European Union had raised some questions from businesses, he was optimistic about plans to overcome logistical problems.
"I don't think it is a secret that our company, together with all of the corporate world, was not fascinated with the idea that the UK will separate from Europe," he said.
"But we face the reality that this is the will of the United Kingdom's people and we have been working for years now to come to a solution when this transition happens.
"So I believe that all of us have organised their logistics to overcome these types of challenges and hope that things will go well."
Earlier this week, Moderna released preliminary data for its vaccine, showing similar effectiveness.
