HYDERABAD: Coronavirus’ Delta variant and its sub-lineages were responsible for vaccine breakthrough infections in Hyderabad and other parts of Telangana through the second wave of Covid-19, reveals a study by a team of city researchers. Vaccine breakthrough infections were observed in people vaccinated by either Covishield or Covaxin.
The study, involving genome-wide analysis by Asmita Gupta, Reelina Basu and Murali Dharan Bashyam of the laboratory of molecular oncology, Centre for DNA Fingerprinting and Diagnostics (CDFD), revealed that there was a sudden change in the landscape of the nucleotide variations (NV) of the novel coronavirus coinciding with the second wave.
The study also revealed that the Delta sub-lineages were marked by presence of several NVs over and above those that defined the Delta. Also, Delta sub-lineages like AY.20 and AY.39 had relatively higher numbers of NVs compared to other sub-lineages observed in Telangana.
The study was published in preprint server MedRxiv recently.
“A large fraction (70%) of vaccination breakthrough cases belonged to the Delta lineage, followed by (sub-lineages) AY.44 (5.2%), AY.20, AY.43, and AY.39 (5% each). Interestingly, 57%, 39%, 29%, and 22% of all samples classified as AY.32, AY.43, AY.35, and AY.20 respectively, belonged to vaccination breakthrough cases,” the researchers said.
The genome-wide analysis also gave an insight into the novel coronavirus variants and their sub-lineages that were in circulation in Hyderabad and Telangana during the second wave of Covid-19. It revealed that there were several nucleotide variations completely mutually exclusive with those associated with previously circulating lineages.
There was also a preferential co-occurrence of specific nucleotide variations in Delta sub-lineages but absent from Delta itself. The study suggested a higher enrichment of certain co-occurring nucleotide variations in vaccination breakthrough (compared to other) cases.
As part of the study, the team had analysed the whole genome sequence of 3,543 Covid-19 samples from Telangana collected between April 2020 and October 2021.
“The dataset included 313 vaccination breakthrough cases, of which 244 belonged to Telangana. Of these, 154 were completely vaccinated, 149 had received only one vaccination dose, while the status of 10 was unavailable,” the researchers said.
