The Delta variant first identified in India now comprises 91% of cases of coronavirus in the UK, the Health Secretary has said.
Matt Hancock told MPs this was according to an assessment he saw on Wednesday evening.
Mr Hancock was speaking on Thursday during more than four hours of questioning by MPs on the science and health committees.
The UK Government is expected to decide next week whether to proceed with a further easing of restrictions in England on June 21, dubbed “freedom day” by some, amid concerns about the dominant variant.
According to Professor Neil Ferguson, whose modelling was instrumental to the UK locking down in March 2020, it may be 60% more transmissible than the Alpha variant which swept across the UK over the winter peak.
Elsewhere, the World Health Organisation’s Europe director warned that the Delta variant first identified in India was “poised to take hold in the region” as many countries prepare to ease restrictions.
Dr Hans Kluge said it had shown signs of being able to evade some vaccines and that some vulnerable people remained unprotected.
“We have been here before,” he said. “Over the course of last summer, cases gradually rose in younger age groups and then moved into older age groups, contributing to a devastating resurgence.”
Dr Kluge said that the spike in Covid-19 cases ultimately led to more lockdowns and deaths in the autumn and winter of 2020, adding: “Let’s not make that mistake again.”