With the largest cluster of Covid-19 cases in Europe, Italy is taking drastic measures to contain the spread of the virus.

All schools and universities are closing. More than €3.5 billion has been raised as an emergency fund for businesses affected by the crisis. Sporting events are being closed to the public.

"Italy should be a warning to everybody, everywhere", says Professor Massimo Galli, who specialises in infectious diseases at the University of Milan.

Speaking to RTÉ News from his office in Milan, he said the measures being taken by Italy are "the minimum necessary".

He believes the lockdown implemented by China could point the way to containing the spread of the coronavirus, but he believes it is too soon to tell.

The death toll from Covid-19 has exceeded 100 in Italy and there are more than 3,000 confirmed cases of the illness.

Asked to explain the prevalence of the coronavirus in Italy, Professor Galli believes the country was unfortunate to experience infection early, before there was a high degree of awareness among the public or medical professionals.

"We have an epidemic because of one person who returned with an infection in an asymptomatic phase and it spread underground in the 'red zone'," he said, referring to the Lombardy region in the north of Italy. "The fire spread in a large part of our region."

"What happened in Italy could happen everywhere in Europe," he said. "Maybe we are particularly unlucky."

The usually bustling square in front of the Colosseum in Rome is much quieter today

Read more: Coronavirus: Inside Italy's red zone

The number of cases of the virus doubles within four days, Prof Galli estimates, with 2.2-2.6 people on average becoming infected through contact with carriers of the virus.

In an intensive effort to trace the path of the virus and those who have come into contact with it, Italy is also testing more people than other countries.

Official government figures from the start of this month showed almost 25,000 people had been tested.

Under 10% of those tested had the virus, but given the sample size and the rate of infection in Italy, the number of confirmed cases at that time was more than 2,000.

"I am sure we will find other people," says Prof Galli.

"The virus circulated for several weeks before people were identified and sick people were found. People became infected without significant symptoms. The number of patients will increase in the next days."

Italy restricted flights to China before other countries, a move he believes was wrongly criticised at the time. But he accepts that limiting direct travel to the zone was not enough to prevent travel from affected areas to Italy.

"There are other ways people can arrive, with flights through other countries and through the Schengen zone," he added.

"It is impossible to forecast a finish to this," said Prof Galli.

"The next weeks will make clear whether it can be stopped or not. We have to wait and see, but we cannot wait without taking measures that are possibly more strict."