The W.H.O. says the European soccer championships are driving virus cases. The E.U. is urged to help African nations buy vaccines.
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.