Background and objectives: India had faced a devastating second outbreak of COVID-19 infection, in which a majority of the viral sequences were found to be of the B.1.617.2 lineage (Delta-variant). While India and the world focused on vaccination, reports of vaccine-immunity evasion by the virus, termed “breakthrough cases”, emerged worldwide. Our study was focused on the primary objective to identify the mutations associated with breakthrough infections SARS-CoV-2. Methods: In our study, we extracted the SARS-CoV-2 RNA (ribonucleic acid) from reverse transcription-polymerase chain reactio...