According to epidemiologists, coronoviruses have mutated several times since first emerging in China in 2019. On Friday, South Africa reported that it had identified a version stating that it was driving a new wave of infection. Scientists said it was different from the one identified in Britain.
Most of these variants are not significant or widespread. But as the number of infected people – and, presumably, some immunity has developed – increases, the pressure of the mutation on the pathogen also increases. Some of the newer variants may be more contagious or cause more severe disease than older versions of the virus.
For months, Mr. Johnson has struggled to balance his reaction to the virus, with pressure not to further harm the economy. At times, he lagged behind banning other European leaders. At other moments, he appeared to be opposing the advice of his own government’s scientific advisors.
In Britain, there were 27,052 new cases and 534 deaths on Saturday. The country has the highest death toll in Europe from the epidemic. Mr Johnson pointed to the rollout of a vaccine, which the UK approved and began to administer as a silver lining from other Western countries. He said 350,000 people in the country had received their first dose of the Pfizer-BioNotech vaccine, a two-shot diet.
But as the economy has declined, the lockdowns have broken politically. When the government placed Manchester, Liverpool and other northern cities where the rate of infection was high, at a more restrictive level, local authorities complained that they were being unfairly targeted. Life in London, he noted, remained mostly unchanged.
Last week, amid indications that London had become a new hot spot, Mr Johnson placed the highest level of ban on Tier 3 in the capital and southeast. But he retracted from his Christmas promise from December 23 to December 27, even inspiring people to keep family gatherings brief and short.