Social distancing measures may continue in the UK for the rest of the year, the British chief medical adviser said on Wednesday.
Prof Chris Whitty said he was confident the next few months would lead to a “proof of concept” vaccine.
But Prof Whitty said the likelihood of having that, or a treatment, this year is “incredibly small”.
He was speaking at the government’s daily briefing where ministers have tried to avoid giving times for lifting the lockdown.
So far, the country's three-week lockdown has been extended to six, with the possibility of it being further prolonged in May.
"We have to be very realistic," Prof Whitty said.
"If people are hoping it’s suddenly going to move from where we are in lockdown to where suddenly everything is gone, that is a wholly unrealistic expectation.
“We are going to have to do a lot of things for really quite a long period of time. The question of what is the best package is what we’re trying to work out."
Prof Whitty said that in the long run, the solution to the coronavirus outbreak would rely on either or both of two things, the first of which is the development of a vaccine.
The second is highly effective drugs that can save patients, or that can help vulnerable people to avoid the disease.
“Until we have those ... we’re going to have to rely on other social measures, which of course are very socially disruptive as everyone is finding at the moment," Prof Whitty said.
“But until that point, that is what we will have to do. It will be the best combination that maximises the outlooks but it’s going to take a long time and I think we need to be aware of that.”
The UK has so far had more than 133,000 coronavirus cases and more than 18,000 deaths.
Prime Minister Boris Johnson was one patient but he is now recovering.
There have been questions about the government’s handling of the crisis, particularly the availability of personal protection equipment for medics.
The lockdown has been widely supported but if it were to last for months there is no guarantee the government would keep public opinion on its side.