The B.1.617.2 variant of the Covid-19 virus which was first detected in India, has been classified as a variant of concern by the World Health Organisation (WHO). The variant has three lineages but only one strain of the Covid-19 Delta variant is now considered "of concern", while two other strains have been downgraded. The variant has higher transmissibility and has now spread globally to over 54 countries. Here's everything you need to know about this.