The United States reaped the fruits Friday of its vaccination campaign against Covid-19 as it became the first nation to reach 100 million people, but Europe's rollout faced fresh impediments and South America tightened restrictions in the face of Brazil's soaring infections.

The United States reported surging job growth and loosened travel curbs as it reached around half of its adult population with at least one dose, with President Joe Biden vowing to cover the vast majority within weeks.

Led by a revival in the leisure and hospitality industries, the US economy created a mammoth 916,000 jobs in March, the Labor Department said.

But infections remain on the rise in parts of the United States, prompting Biden to urge Americans to keep wearing masks and taking other precautions to stop the pandemic that has killed more than 2.8 million people worldwide.

"I plead with you. Don't give back the progress we've all fought so hard to achieve," Biden said in a brief address.

"We need to finish this job," he said. "We need every American to buckle down and keep their guard up in this homestretch."

The Centers for Disease Control and Prevention, meanwhile, updated guidance to say that fully vaccinated people can travel without observing quarantines, although they should still wear masks.

The United States has suffered a catastrophic Covid toll at more than 550,000 people dead, with health measures polarizing the country since last year when Biden's predecessor Donald Trump criticized restrictions.

New woes in Europe

European nations have been struggling to speed up vaccination and several have returned to unpopular lockdowns, with France banning outdoor gatherings of more than six people.

Some of Europe's vaccination woes come from its reliance on the AstraZeneca jab, yet to be approved in the United States, after reports of blood clotting.

Such incidents are rare and the European Medicines Agency has said AstraZeneca is safe. But the Netherlands on Friday followed Germany in halting jabs of the vaccine for people under the age of 60.

"We must err on the side of caution, which is why it is wise to press the pause button now as a precaution," Dutch Health Minister Hugo de Jonge said.

Only 10 percent of Europe's total population has received one vaccine dose, and four percent have received two, according to the World Health Organization.

The WHO director for Europe, Hans Kluge, on Thursday called the rollout "unacceptably slow."

Also complicating vaccination efforts is that India, often dubbed the "pharmacy of the world," has slowed down exports as it battles a major surge.

India has been ramping up vaccinations, expanding eligibility to everyone over age 45.

But on Friday the country reported 81,000 daily infections and 469 deaths, the highest since October.

Among those contracting Covid-19 was cricket legend Sachin Tendulkar, who checked into a Mumbai hospital as a precaution but said he hoped to return home within days.

China -- where the pulmonary disease first emerged in 2019 in circumstances that remain a topic of intense speculation -- as well as Russia have stepped up exports of their own vaccines.

Chinese biopharmaceutical firm Sinovac said it will double capacity to produce its vaccine to two billion doses a year.

Growing worries over Brazil

One of the worst Covid crises in the world is unfolding in Brazil, which has reported more deaths than any country after the United States with a staggering 66,500 Covid-19 fatalities in March alone.

Latin America's infections have soared past 25 million, according to an AFP tally, likely fueled by a seemingly more contagious variant first detected in Brazil.

Rio de Janeiro on Friday extended restrictions, saying that hospitalizations had started to level off for the first time in weeks.

"You have to give a little more time, no matter how hard it is for companies and for those looking for work to earn a living. These decreases in people-to-people contact are already paying off," Mayor Eduardo Paes told reporters.

The city's famous beaches will remain off limits until April 19, when a daily nighttime curfew will also be lifted.

But he said that schools would reopen for in-person classes Tuesday.

The devastation in Brazil has frightened neighbors already battling their own surging caseloads. Peru and Ecuador announced fresh restrictions and Bolivia sealed the Brazilian border.

"We are in a very critical moment of the pandemic," Chilean government spokesman Jaime Bellolio said as he announced a closure of borders starting Monday.

Brazilian President Jair Bolsonaro, a far-right ally of Trump, has dismissed the dangers of the virus and aired conspiracy theories, with the country's military chiefs and top ministers exiting in recent days amid the turmoil.

At a field hospital in the suburbs of Sao Paulo, one doctor said she was alarmed at the spread of the virus -- and frustrated to see many of her compatriots ignore face masks, shun social distancing guidelines and even flood to underground parties.

"I see no difference in people's behavior. People don't seem to understand the magnitude of this," said 53-year-old surgeon Marise Gomes.