RENNES, France -- Less than two months after France ended compulsory mask wearing outdoors several coastal resorts have made it mandatory again to combat a fourth wave of COVID-19 infections.

Brittany's Finistere area, which includes the towns of Quimper, Morlaix and Brest, became the latest on Monday to order people to cover their mouths and noses outdoors after a jump in Covid cases since the start of the summer holidays.

With its rugged Atlantic coastline Brittany is one of France's most popular destinations.

Authorities in Finistere said the number of cases per 100,000 inhabitants had risen over four-fold between June 30 and July 30, from 19 to 90.

Last week, masks also became compulsory outdoors again in the Morbihan area, which covers the town of Vannes, and the Cotes-d'Armor, including Dinan and Saint-Brieuc.

Other areas to have revived compulsory mask-wearing outdoors include the Mediterranean island of Corsica, the foothills of the Pyrenees, on the border with Spain and Lake Annecy, at the foot of the Alps.

Health authorities in Corsica said Tuesday that hospitals would start cancelling elective surgery as they struggle with an influx of Covid patients.

They blamed the spread of the Delta variant for an incidence rate of 830 cases per 100,000 people in the north of the island, compared with a national average of 224 cases per 100,000.

President Emmanuel Macron has taken to Tik Tok and Instagram to try convince young people to get vaccinated.

Some 16 million people have since Monday viewed four video selfies by the French leader trying to debunk false claims about the jabs.

So far, 42.6 million people in France have received at least one vaccine shot, representing 63.2 percent of the population. Of these, 35.7 million are fully vaccinated.