Genomic analysis of early SARS-CoV-2 breakthrough infections from the state of Kerala suggest a preponderance of variants of concern

The SARS-CoV-2 Variant of Concern, Delta (B.1.617.2) was first reported in December 2020 in India and has spread colossally throughout the globe. Owing to factors like increased transmissibility, immune escape, and virulence, the delta variant has been considered as a potential public health threat apart from other variants of concern like alpha, beta and gamma. Kerala was one of the first states in India to enroll in the systematic genomic surveillance. In the present report, vaccine breakthrough infections were followed up in 147 patients including 55 healthcare workers who had been vaccinated with ChAdOx1 nCoV- 19/BBV152 across eleven districts from the state of Kerala. The timeline of samples analysed were from April 2021 till June 2021. Severity of the infections reported in the enrolled patients found to be mildly symptomatic, majorly with only 0.7% (n=1) of the cohort to be asymptomatic. Genomic analysis of the samples revealed the Delta variant (B.1.617.2) to constitute about 81.6% (n=120) in the studied cohort. This was followed by the Kappa variant B.1.617.1 (8.35%, n=9), AY.1 (0.6%, n= 1), AY.12 (0.6%, n= 1), AY.4 (1.2%, n= 2), AY.9 (1.2%, n= 2) and Eta variant, B.1.525 (0.6%, n= 1). 11 samples were not assigned any lineage. Evidence from this study suggests the preponderance of the Delta variant in the samples analysed