According to Public Health England, the Delta variant has a CFR of 0.2% (0.2 to 0.3%). The Alpha (UK) variant has a CFR of 1.9% (1.8 to 2.0%).

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1001358/Variants_of_Concern_VOC_Technical_Briefing_18.pdf