Almost half of those who have tested positive for coronavirus in Italy show “no or minimal symptoms”, new figures have revealed.

Data released by the country’s National Institute of Health (ISS) on Monday shows 45 per cent of patients do not exhibit anything more than mild symptoms.

One in ten people with the illness display no symptoms at all.

The data also reveals that 22 per cent of infections have been detected in people aged between 19 and 50.

As such, Silvio Brusaferro, president of the ISS, warned young people in Italy to abide by official health recommendations.

Dr Muge Cevik, a virology clinician and research at the University of St Andrews, said in a tweet that almost half of people had “either no or minimal symptoms”, adding that the data was a reminder that coronavirus is “not a disease of the elderly”.

Dr Cevik added: “All age groups contribute. Especially those who feel well with minimal symptoms are more likely to contribute to the spread of infection.”

Since Sunday, the death toll in the country has risen by almost 100 to 463, with the total number of cases standing at 9,172.

The figures make Italy the second-most affected country in the world behind China.

Prime minister Giuseppe Conte announced at a press conference on Monday that the entire country would be on lockdown from Tuesday in an attempt to restrict the spread of the disease.

Mr Conte also criticised young people who have been meeting up at night in social gatherings despite the public health emergency which began on 21 February.

He said: “This nightlife... we can’t allow this any more.”

Some doctors in Italy have compared the current situation to war-time, as they are forced to decide which patients should use the scarce beds available.

Dr. Massimo Galli, head of infectious disease at Milan’s Sacco hospital, said: “Unfortunately we’re only at the beginning.”

Meanwhile, protests have taken place in prisons across Italy because of visiting restrictions that have been put in place.