LONDON (Reuters) – Britain reported its highest daily total of new coronavirus infections in a month while cases of a variant of concern first found in India continue to climb, official statistics showed on Thursday.

The overall incidence of infections in Britain is still low, while the number of people in hospital with COVID-19 fell to its lowest level since September on Thursday.

But clusters of the B.1.617.2 variant, believed to be more transmissible than the dominant Kent variant, are growing quickly, and could derail Prime Minister Boris Johnson’s plans to reopen England’s economy by the summer.

British cases of the B.1.617.2 variant first found in India have risen to 3,424, up by 2,111 compared to comparable figures last week, Public Health England said.

It also represents a steep rise compared to figures given on Wednesday, when Health Minister Matt Hancock said there had been 2,967 cases of the variant.

“PHE will continue to monitor all variants closely, paying particular attention to the impact on hospitalizations and deaths which will help us to understand the protective effects of the vaccine,” said Meera Chand, COVID-19 Incident Director at PHE.

Britain reported 2,874 new COVID-19 cases on Thursday, the highest daily figure for new cases since April 19

The uptick comes as Johnson eases restrictions in England, and as a quick rollout of vaccines decouples the link between case numbers and hospitalizations and deaths.

On Thursday, the total number of patients in hospital fell below 900 for the first time since September.

Britain recorded another 7 deaths within 28 days of a positive COVID-19 test, and the statistics portal showed 37.25 million people had been given a first dose of vaccine.

(Reporting by Alistair Smout; editing by Kate Holton and Giles Elgood)