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Updated: Aug 23, 2025

Author Spotlight: A Pseudotype Virus System for Assessing Omicron Subvariants and Neutralizing Antibodies in SARS-CoV-2 Research
Published on: September 8, 2023
Prolonged replication of BA.1 and BA.2 Omicron lineages compared to Delta variant in nasopharyngeal samples from
Elisa Teyssou1, Stéphane Marot1, Théophile Cocherie1
1Sorbonne Université, INSERM, Institut Pierre Louis d'Epidémiologie et de Santé Publique, AP-HP, Hôpitaux Universitaires Pitié Salpêtrière - Charles Foix, laboratoire de virologie, F-75013 Paris, France.
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.
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