Italy will impose tighter restrictions in Sicily after a surge in cases.

The Italian government announced on Friday that it would impose tighter restrictions on the southern island of Sicily, including an outdoor mask mandate. The announcement followed a sharp increase in coronavirus infections and hospitalizations in the region, where vaccination rates are low.

“It is confirmation the virus has not been defeated yet and that the priority is to keep investing in the vaccination campaign,” Roberto Speranza, Italy’s health minister, said in a statement.

The new rules, which will also limit to four the number of people who can sit at restaurant tables, will be effective on Monday. Doctors say they illustrate the direct consequences of shunning vaccines.

In Sicily, about 55 percent of the population is fully vaccinated, the lowest rate in Italy, and hospitals are filling up with unvaccinated Sicilians.

In Palermo, Sicily’s capital, 80 percent of the hospitalized Covid patients are unvaccinated, and a vast majority of those in the I.C.U. have not received a vaccine, said Dr. Renato Costa, the city’s Covid emergency commissioner. Similar rates are observed throughout the region.

“If we had a higher vaccination rate,” said Dr. Costa, “our hospitals would be emptier.”

Local doctors said the drop in vaccination rates during the month of August was related to the summer holidays, a time when it is more difficult to distribute shots to the region, which has among Italy’s lowest income and education levels.

Over the past weeks, doctors have scrambled to reach and vaccinate Sicilians.

They gave out olive oil, pistachio spread and tickets for Palermo soccer matches to those who agreed to get vaccinated. They provided shots at beaches and pizzerias. To inoculate older and marginalized residents, they brought doses to a local taverna in the low-income Vucciria neighborhood in Palermo and to the Zen, the housing project north of the city.

Last weekend, doctors drove vaccine trucks to a carnival celebration near the city of Catania, and on Monday, they installed a vaccination center inside an ice cream shop in Palermo.

The new restrictions followed an increase in hospitalizations, with a large majority of cases involving unvaccinated people.

“We tried all the paths in these months to make the Sicilians get a vaccine,” Nello Musumeci, the region’s president, wrote on Facebook on Tuesday, decrying the high number of unvaccinated Sicilians in the island’s hospitals. “It is time all of us become aware of the civic duty to protect themselves.”