SARS-CoV-2 Omicron variant, lineage BA.1, is associated with lower viral load in nasopharyngeal samples compared to Delta variant

AbstractHigh viral load in upper respiratory tract specimens observed for Delta cases may contributed to its increased infectivity compared to the Alpha variant. Herein, we showed that the RT-PCR Ct values in Health Care Workers sampled within five days after symptom onset were significantly higher for Omicron cases than Delta cases (+2.84 Ct, p=0.008). This result comfort the studies showing that the increased transmissibility of Omicron is related to other mechanisms than higher virus excretion.