British authorities said on Friday that they are considering changing vaccination protocols and reintroducing local lockdowns to stem the spread of a coronavirus variant first detected in India, a warning sign for countries that are easing restrictions even though their own vaccination campaigns are incomplete.
The numbers of cases involving the variant, known as B.1.617, rose from 520 last week to 1,313 cases this week in Britain, according to official statistics.
The extent to which the variant has spread globally is unclear, because most countries lack the genomic surveillance capabilities employed in England.
That surveillance capability has allowed health officials in Britain to spot the rise of concerning variants more quickly than other nations, offering an early warning system of sorts as a variant seen in one nation almost invariably pops up in others.
Most cases detected in Britain are in northwestern England. The focus has been on Bolton, a town of nearly 200,000 that has one of the country’s highest rates of infection and where health officials have warned of widespread community transmission of the variant. Some cases have also been reported in London. The rapid spread of the variant has led officials to debate speeding up dosing schedules and opening up access to shots in hot spots to younger age groups.