Delta (B.1.617.2)
The Delta variant was first detected in India in May 2021 and has now been verified in 176 locations worldwide, rapidly overtaking existing variants to become the dominant variant in many countries. Delta contains the D614G mutation, plus many additional ones not seen in other variants of concern. These include an L452R mutation, which is thought to increase infectivity, and may help the virus to evade destruction by immune cells; a T478K mutation, thought to help it avoid recognition by the immune system; and a P681R mutation, which is associated with an enhanced ability to trigger severe disease. There have also been reports of a ‘Delta plus’ variant, which was first identified in Nepal and carries an additional K417N mutation.
