The UK, South Africa and Brazil variants could be much more contagious than earlier versions. All three have undergone changes to their spike protein – the part of the virus which attaches to human cells. As a result, these variants seem to be better at infecting cells and spreading.
However, there is no evidence that any of them cause much more serious illness for the vast majority of people who become infected.
As with the original version, the risk is highest for people who are elderly or have significant underlying health conditions.
Measures such as washing your hands, keeping your distance from other people and wearing a face covering will still help prevent infections, and because the new variants appear to spread more easily it is important to be extra vigilant.
Covid: How worrying are the UK, South Africa, and Brazil coronavirus variants? (BBC)
What we know about the South African Covid-19 variant (BBC Future)
SARS-CoV-2 variants (WHO) (NNT World)