The president of the Lazio region, which includes Rome, said reservations had restarted using a new website, while a temporary version of the original, regional site that was targeted would launch on Monday.
“Following the work of the past few days, we are now able to present a schedule of services we’re reactivating,” said region chief Nicola Zingaretti.
“The vaccination booking system is operational this afternoon.”
Access to other digital services from the region would roll out again in days and weeks to come, he said.
The region’s official website suffered a massive ransomware attack on Saturday night, a form of malware that encrypts the victim’s files.
Although typically a ransom is demanded in exchange for the key to decrypt the data, no such ransom request had been made, Zingaretti said.
A terrorism investigation has been opened, but the authors of the attack are still unidentified. Zingaretti said the hack had come from abroad.
“One can’t have any certainty about where these attacks came from because the methods used through the internet make it very difficult to identify the true source,” the head of Italy’s parliamentary commission on security, Adolfo Urso, told Mediaset’s TG4 television programme on Wednesday.
Some 66 percent of the adult population in Lazio has been fully vaccinated, according to officials, and 62 percent in Italy overall, over the age of 12.
In June, Italy’s government set up a new agency specialised in cybersecurity in order to fight against an increasing number of attacks.