It had been the epicenter of the pandemic in Europe since January, and large numbers of deaths and hospitalizations overwhelmed a health care system that had already been overstretched by the first wave last year. But the country now appears to be walking out of the pandemic, while places like France, Germany and Italy face a third wave of infections.
Still, there are growing concerns that new variants will soon spread in Britain, in addition to the first discovered in the country late last year — an emergence that led to strict lockdown measures and travel restrictions around the world.
Neil Ferguson, a former adviser to Mr. Johnson on the pandemic, said on Friday that he was concerned about the spread in Europe of the variant first discovered in South Africa.
Early research suggests that the variant, which accounts for a significant portion of new cases in countries like France, may weaken the efficacy of some vaccines. That includes the AstraZeneca vaccine, which is central to Britain’s inoculation drive.
The head of England’s National Health Service, Simon Stevens, 54, also received his first injection of the AstraZeneca vaccine this week, as did Prime Minister Jean Castex of France, 55, who flashed a thumbs-up at television cameras after getting his shot at a military hospital southeast of Paris.
The nearly simultaneous public inoculations of Mr. Johnson and Mr. Castex underscored how public officials in Europe have tried to restore public confidence in the AstraZeneca vaccine, after several countries in the European Union, including France, paused its use this week.
But Britain and France have found themselves in very different situations: Britain, which left the European Union last year, has vaccinated its population at a more rapid pace than France and other countries of the bloc. And British officials have been staunch defenders of the AstraZeneca vaccine, which was developed in conjunction with the University of Oxford.