The Delta variant is the primary cause behind the second COVID wave, finds a study carried out by scientists of INSACOG (the consortium of labs undertaking genome sequencing in India) and National Centre for Disease Control (NCDC) on the reasons behind the second wave.
The B.1.617 variant and its lineage B.1.617.2 were primarily responsible for surge in cases with high transmissibility of 50% more than Alpha variant (B.1.1.7), as per the study.
The Delta variant is present in all states, but has infected most in Delhi, Andhra Pradesh, Gujarat, Maharashtra, Odisha and Telangana, which were the worst hit in the second surge.