Changing SARS-CoV-2 variants in Karachi, Pakistan from alpha to delta through COVID-19 waves three and four

Abstract We investigated the presence of SARS-CoV-2 variants of concern (VoC) in Karachi, Pakistan between April and July 2021 in specimens received at the Aga Khan University Clinical Laboratories. VoC were identified using a PCR based approach targeting lineage specific mutation. Of the 710 clinical isolates tested, 63% were VoC comprising; 36% alpha, 37% beta, 7% gamma and 21% delta variants. Alpha variants remained the majority whilst, delta strains increased to 43% of cases in July. Thirty-six per cent of all cases were admitted COVID-19 in-patient samples. Of the in-patient cases, 41% were alpha, 28% were beta, 8% were gamma and 24% were delta variants. Overall, we report an increase of delta variants in Karachi over the past two months which is concordant with the currently observed exacerbation in COVID-19 morbidity and mortality.