Characterizing the SARS-CoV-2 Omicron variant shedding and duration of RT-PCR and rapid antigen test positivity on vaccinated individuals.

Abstract The SARS-CoV-2 Omicron variant has demonstrated increased transmissibility and ability to escape natural and vaccine-induced immunity. We aimed to characterize the duration of Omicron’s shedding by comparing viral isolation to rapid antigen test (RAT) and real-time polymerase chain reaction (RT-PCR) positivity. Thus, we performed a cross-sectional study of 30 vaccinated individuals with mild COVID-19 to evaluate the ability to infect Vero cells at day 5, 7, 10 and 14 since symptoms onset. Viral growth was observed in 46% and 20% of respiratory samples at day 5 and 7, respectively, while all were negative from day 10. RAT showed 100% of sensitivity during the first 7 days of symptoms compared to viral isolation, being a better infectivity predictor than RT-PCR Ct values. In conclusion, immunocompetent vaccinated individuals with Omicron infection can still transmit the virus on the 7th day of symptoms. This data may impact decisions on end-isolation protocols for mild COVID-19.