ROME — Italy added 18,627 new COVID-19 cases on Sunday, raising to 2,276,491 the nation’s number of confirmed coronavirus infections in the pandemic.

Since the previous day, 361 deaths of patients with COVID-19 were registered, boosting the overall known death toll to 78,755, according to the Health Ministry.

The latest infections follow a period of year-end holiday restrictions, including limits on residents’ travel but with some allowances for visiting family or friends.

Starting Monday, Italy returns to a three-tier system, with economic and social activity limits determined by how each region is faring in terms of rate of contagion, availability of ICU beds and other factors.

In a nation of some 60 million people, more than a half-million currently positive persons are isolating at home, with some 26,000 in hospital. In the pandemic’s initial surge, more than two months of severe nationwide lockdown measures saw numbers of new infections and deaths eventually drop drastically.

But after measures were largely relaxed over the summer, cases started rapidly rising again and have stayed stubbornly high in number.