Covid-19: how and why is the virus mutating?

The new Covid variant, B117, is rapidly spreading around the UK and has been detected in many other countries. Although it is about 50% more infectious than previous variants, B117 does not seem to cause more severe disease or be immune to current vaccines. Yet it has raised concerns over how the virus may adapt to our antibodies and vaccines in the future. To explore these issues, the health editor, Sarah Boseley, speaks to Prof Ravi Gupta about how and why viruses mutate. Help support our independent journalism at