The virus’s behaviour will be a key factor in how it affects the UK and the wider world, with further mutations almost certain
What is the Delta variant?
The Delta variant, also known as lineage B.1.617.2, is a version of Sars-CoV-2, the virus that causes Covid-19. It was first detected in India late last year and contains mutations in the gene that codes for the spike protein which the virus uses to enter cells in the body. According to Public Health England (PHE), this has provided the Delta variant with a transmissibility that is 50%-60% higher than the virus’s Alpha variant. Professor Wendy Barclay of Imperial College London says the Delta variant appears to allow increased amounts of the virus to build up in infected people so they expel more to infect other individuals.
How fast has it spread in the UK?
The Delta variant first appeared in England at the end of April and has quickly become the dominant version of Covid-19 across the UK. As of last week, 94% of new cases have been attributed to the Delta variant. There are also concerns that current vaccines are less able to protect against the variant, although the latest PHE figures suggest two doses of either vaccine are still highly effective against hospitalisation: 96% for Pfizer/BioNTech and 92% for Oxford/AstraZeneca.
