“As of today, throughout Italy we’ve started administering the booster shot to the most vulnerable,” Speranza told news outlets on Monday.

“This is an important step forward in providing protection to those with weaker immune systems.

“Once again, thanks to all health workers”.

The third round of Italy’s vaccination campaign will focus initially on those with the most fragile immune systems – around three million people according to Italian news agency ANSA.

Speranza said health authorities would then decide to give the booster to the over-80s and residents of nursing homes, as well as aged care workers and medical workers on the frontline.

Italian medicines agency AIFA recommends the Pfizer and Moderna vaccines for the third dose, according to ANSA.

The Pfizer vaccine will be used for patients aged 12 and up, and Moderna can be used for patients who are 18 and older.

For immunosuppressed people, the third vaccine can be administered 28 days after the second dose – and should be given as soon as possible after that point, according to the health ministry’s latest guidance.

Boosters for all other categories, meanwhile, should be administered at least six months after the second shot.

While infectious disease experts in Italy agree that booster shots are necessary for vulnerable groups, some say they remain unsure if a third dose will be necessary for the entire population.

More than 40 million people in Italy have been fully vaccinated against the coronavirus, equal to 74 per cent of the population over 12, as the government nears its target of vaccinating 80 per cent by the end of September.

Vaccination bookings have soared since the government announced last week that the Italy’s “green pass” will be compulsory for all workplaces in the country from October 15.

Employees who go to work without the pass will be suspended and go without pay after five days; they will also face fines of between €600 and €1500, according to Italian news agency ANSA.