Dynamics of SARS-CoV-2 variants characterized during different COVID-19 waves in Mali

The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants may have contributed to prolonging the pandemic, and increasing morbidity and mortality related to coronavirus disease 2019 (COVID-19). This article describes the dynamics of circulating SARS-CoV-2 variants identified during the different COVID-19 waves in Mali between April and October 2021.

The respiratory SARS-CoV-2 complete spike (S) gene from positive samples was sequenced. Generated sequences were aligned by Variant Reporter v3.0 using the Wuhan-1 strain as the reference. Mutations were noted using the GISAID and Nextclade platforms.

Of 16,797 nasopharyngeal swab samples tested, 6.0% (1008/16,797) tested positive for SARS-CoV-2 on quantitative reverse transcription polymerase chain reaction. Of these, 16.07% (162/1008) had a cycle threshold value ≤28 and were amplified and sequenced. The complete S gene sequence was recovered from 80 of 162 (49.8%) samples. Seven distinct variants were identified: Delta (62.5%), Alpha (1.2%), Beta (1.2%), Eta (30.0%), 20B (2.5%), 19B (1.2%) and 20A (1.2%).

Several SARS-CoV-2 variants were present during the COVID-19 waves in Mali between April and October 2021. The continued emergence of new variants highlights the need to strengthen local real-time sequencing capacity and genomic surveillance for better and coordinated national responses to SARS-CoV-2.