The first administrations of second booster shots, or fourth doses, for the most at-risk groups began on Tuesday in the province of Rieti, Lazio, according to local media reports.
Fourth doses will soon become available across the Lazio region and in other parts of the country, with the northern region of Lombardy, around Milan, rolling out fourth doses from Thursday.
Italian medicines agency AIFA approved the second booster after the European Medicines Agency (EMA) ruled in favour last week.
The jabs are currently authorised in Italy for over-80s, care home residents and over-60s who are classed as vulnerable, and who had their last dose at least 120 days previously.
A fourth shot for those with compromised immune systems has been available since March.
For these categories, a fourth dose can be booked as usual, via pharmacies or family doctors, and via regional booking websites where available. (Find more information in a separate article here.)
It is not yet known if or when Italy may offer fourth doses to other groups.
Health authorities have previously said they are not planning to make a fourth dose mandatory, though an annual “top-up” shot is likely to be offered.
Health Minister Roberto Speranza said in February that annual shots of a Covid-19 vaccine for the general population are “probable”, though confirmation will come later in the year.
“We will have to evaluate [fourth doses] for everyone after the summer,” Speranza said at the time. “It is to be considered probable, because the virus won’t shake hands and leave forever, unfortunately,”