ROME (AP) — Protests erupted in Italy on Friday as one of the most stringent anti-coronavirus measures in Europe went into effect, requiring all workers, from magistrates to maids, to show a health pass to get into their place of employment.

Police were out in force, schools were closing early and embassies issued warnings of possible violence amid concerns that anti-vaccination demonstrations could turn violent, as they did in Rome over the weekend.

Protests by port workers in Genoa and Trieste threatened to affect commercial activities, but early reports suggested the ports were operational. Protesters shouted “Liberta" (Freedom) in a largely peaceful demonstration in Florence.

The so-called “Green Pass” shows proof of vaccination, a recent negative test or of having recovered from COVID-19 in the past six months. Italy has required it to access all sorts of indoor activities for weeks, including dining , visiting museums and theaters and on long-distance trains.

But the addition of the workplace requirement has sparked heated debate and opposition in the onetime epicenter of the outbreak, where vaccination rates are nevertheless among the highest in Europe and where even the latest delta variant-fueled resurgence has been kept largely under control.

Not even the Vatican was spared: Three Swiss Guards quit and another three were suspended after they refused to get vaccinated before the Vatican's Green Pass requirement went into effect.