Delta variant 60% more transmissible, reduces vaccine effect, UK experts say

The rapid surge in cases during Delhi’s fourth Covid-19 wave was mainly driven by the Delta variant, which likely has immune-evasion properties and accounted for 60 per cent of the cases in April, according to a new study.

The Delta variant, B.1.617.2, is 50 per cent more transmissible than the Alpha variant, B1.117, first discovered in the UK, say researchers from the National Centre for Disease Control (NCDC) and the CSIR Institute of Genomics and Integrative Biology (IGIB).

Prior infections, high seropositivity and partial vaccination are “insufficient impediments” to the spread of the Delta variant, found the scientists. They traced the factors contributing to the scale and speed of the fourth wave that started in April in Delhi and compared them to the preceding three waves last year.