Prolonged replication of BA.1 and BA.2 Omicron lineages compared to Delta variant in nasopharyngeal samples from COVID-19 patients

Abstract

Objectives: We aimed to characterize and compare the viral loads (VL) of the Omicron BA.1 and BA.2 lineages and the Delta variant in nasopharyngeal samples from newly diagnosed COVID-19 patients and their kinetics over time.

Patients and methods: The kinetics of the VL were measured on the CT data from 215 SARS-CoV-2 positive patients who presented at least two positive PCRs a day apart and were screened for SARS-CoV-2 viral lineages.

Results: We observed no significant difference in median CT value during the first diagnostic test between the Delta variant and the two Omicron lineages. However, the kinetics of CT decreases for the BA.1 and BA.2 lineage were significantly lengthier in time than the kinetics for the Delta variant. The BA.2 lineage presented lower median CT value (-2 CT) (inversely proportional to the VL) than the BA.1 lineage.

Conclusions: BA.2 Omicron lineage presented higher VL than BA.1 Omicron lineage at diagnostic. Omicron BA.1 and BA.2 lineages have more prolonged replication than the Delta variant.

Keywords: BA.1; BA.2; Kinetic; SARS-CoV-2; Viral load.