ROME－Millions of Christians around the world have been enduring another Easter holiday weekend under movement restrictions because of a resurgent coronavirus.

Worrying spikes in infections are stretching governments in their responses to COVID-19, but in the United States there was good news with the worst-hit nation crossing the milestone of 100 million vaccinations.

In a number of regions, the increases in infections are being logged even as vaccine rollouts gather pace. Many countries have been forced to reimpose restrictions.

Italy began a strict Easter lockdown on Saturday, with the entire country deemed a high-risk "red zone" during a time when families usually get together.

At Rome's normally bustling Piazza Navona, site of the famed Fountain of the Four Rivers, a scattering of dog walkers and cyclists could be seen enjoying the spring weather.

Shops selling essentials were open in the nearby winding streets, but without the normal throngs.

New curbs were also coming into force on Saturday in France, where authorities are scrambling to deal with a dramatic rise in cases that has overwhelmed hospitals in Paris.

Restrictions had already been stepped up in other European nations such as Belgium.

Germans protested in their thousands on Saturday amid heated debate throughout the country over restrictions in the face of a third wave of COVID-19.

The government scrapped plans for a strict Easter lockdown, but, ahead of the break, Chancellor Angela Merkel urged people to limit their social contacts.

One of the worst COVID-19 outbreaks is devastating Brazil, which has reported more deaths than any country after the US.

It is the epicenter of an unfolding crisis in Latin America, where infections have soared past 25 million, likely fueled by a more contagious variant first detected in Brazil.

Peru has gone into an Easter lockdown, Chile has closed all borders, Ecuador has announced fresh restrictions and Bolivia has sealed the border with Brazil.

Argentina's President Alberto Fernandez announced late on Friday that he had tested positive for COVID-19.

The pandemic has claimed more than 2.8 million lives worldwide.

On the positive side, the US' progress in administering at least one shot to more than 100 million people－the first country to do so-means around half of all adults have been covered.

But infections remain on the rise in parts of the country, and US President Joe Biden urged people to keep wearing masks and taking other precautions. "We need to finish this job," he said.

The US Centers for Disease Control and Prevention has updated its guidance to say that fully vaccinated people can travel without observing quarantines.

In Europe, vaccination campaigns have struggled to gain traction due to supply issues and questions over a vaccine from AstraZeneca.

On Saturday, the UK medical regulator said that out of 30 people who suffered blood clots after receiving the shot in Britain, seven had died.

Paul Hunter, a medical microbiologist at Britain's University of East Anglia, said he initially thought the link between vaccination and blood clots was likely a "random association".

But as evidence mounts of clusters in separate countries, "the weight of evidence is now looking toward Oxford-AstraZeneca actually being the cause of these adverse events", he said of the vaccine that was co-developed with Oxford University.