Britain is increasingly confident that vaccines work against the coronavirus variant first found in India, Prime Minister Boris Johnson said on Wednesday, with a leading epidemiologist saying it may be spreading less quickly than at first feared.

Johnson has warned that the emergence of the B.1.617.2 variant might derail his plans to lift England’s lockdown fully on June 21, but on Wednesday he said the latest data had been encouraging.

“We have increasing confidence vaccines are effective against all variants, including the Indian variant,” he told parliament.

Johnson last week said the extent to which the variant could disrupt the planned exit from lockdown would depend on how much more transmissible it was.

Neil Ferguson, an epidemiologist at Imperial College London, said there was a “glimmer of hope” from the latest data that the transmissibility of the variant might be lower than first feared.

He said that while there was a “good deal of confidence” that vaccines would continue to protect against severe disease, the variant might lead to reduced vaccine efficacy against infection and transmission.