https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachmentdata/file/986709/S12377SPI-M-OConsensussStatement.pdf
- SPI-M-O is therefore confident that B.1.617.2 has a significant growth advantage over the UK’s currently dominant strain, B.1.1.7. The difference in growth rates between B.1.617.2 and B.1.1.7 is consistent with the former having a transmission advantage of more than 50%;this is based on observed growth that has already happened and it is unclear whether this same growth advantage would apply to sustained wider community transmission regionally or nationally. Resolving this question of the applicability of this growth advantage to the wider population will be difficult while the number of cases are small and relatively focussed.
22. Considering this, it is a realistic possibility that this scale of B.1.617.2 growth could lead to a very large increase in transmission. At this point in the vaccine roll out, there are still too few adults vaccinated to prevent a significant resurgence that ultimately could put unsustainable pressure on the NHS, without non-pharmaceutical interventions.