There are probably between 5,000 and 10,000 people infected with coronavirus in the UK at this time, the government's chief scientific adviser has said.

Sir Patrick Vallance said about 590 cases had been identified but it was likely the real number was much higher.

The "delay" phase had worked well, however, and would help mitigate the strain on NHS services, he said.

He added that closing schools might not have the desired effect.