Will vaccines protect us against the Delta variant?

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.

And in the rest of the world?

India, where the variant was first detected, has borne the brunt of its impact, with the UK coming second in the total number of cases. Germany has also been badly affected, with Chancellor Angela Merkel warning that Europe is on “thin ice” in its battle against the Delta variant. Russia is also struggling against rising levels of infections, reporting more than 20,000 cases last Thursday, its highest total since January. These figures have been spurred largely by the Delta variant. And in Australia and Israel, which have done well in combating Covid-19 recently, restrictions have been reimposed as cases – again driven by the Delta variant – have started to surge.

Can we expect further variants?
The answer is: almost certainly yes. Already a version of the Delta variant – known as Delta Plus – has raised concern among virologists. It was found in at least 22 cases in the Indian state of Maharashtra last week and could be more transmissible than the original Delta variant. PHE has confirmed 41 of the 75,953 UK Delta cases have been caused by the new mutation.


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