The highly contagious Delta variant is surging in countries around the world, from Indonesia to parts of Europe, leading governments to reimpose restrictions just weeks after they had taken steps to return to ordinary life.
The latest example is Portugal, which on Friday will impose a curfew from 11 p.m. to 5 a.m. in Lisbon, Porto and other popular tourism spots, reversing course after it had reopened its economy to prepare for summer travelers.
Scientists believe that the Delta variant may be twice as transmissible as the original strain of the coronavirus. But in countries where high percentages of the population have been vaccinated, the outlook is encouraging, with death tolls and hospitalization numbers remaining low. The vaccines made by Pfizer, Moderna, AstraZeneca and Johnson & Johnson have been found to be effective against the Delta variant.
In Portugal, 34 percent of people are fully vaccinated, compared with about 46 percent in the United States, according to Our World In Data.
Portugal’s new curfews are designed to discourage gatherings of younger people at night, said Mariana Vieira da Silva, a cabinet minister. “This is a time to follow the rules, avoid gatherings, avoid parties and seek to contain the numbers,” she said.
The curfews apply in 19 municipalities ranked as having a “very elevated risk” of Covid-19 and a further 26 with an “elevated risk.” On Thursday, Portugal reported almost 2,500 new cases, the highest daily rise since mid-February, although cases have remained far below its January peak of more 16,000 per day.
In early June, cases in the country had remained so consistently low that Britain allowed its residents to visit without having to quarantine on return. But the day after that announcement was made, London jolted Portugal by downgrading it over concerns about the Delta variant.
London’s decisions were especially significant because Portugal is a popular destination for British tourists, including many who are eager to visit after a year of pandemic lockdowns. The abrupt change in travel rules prompted thousands of tourists in Portugal to catch early flights back to Britain ahead of a quarantine deadline.
The reversal in early June came less than a week after thousands of English soccer fans had visited Porto, in northern Portugal, to watch the final of the Champions League soccer tournament with no quarantine requirement.
Britain is also facing a surge in Delta cases, although its number of death remains low and hospital occupancy is rising much more slowly than in previous waves of the pandemic. As in Portugal, most of Britain’s new cases are among people under 30, and public health officials say that vaccinating younger people is critical to preventing new outbreaks.