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Reverse-transcriptase polymerase chain reaction (RT-PCR) cycle threshold (Ct) values by day past symptom onset (DPSO). Mean Ct values on DPSO among adults and children (A), Delta and Omicron and severe acute respiratory syndrome coronavirus 2 variants (B), vaccinated and unvaccinated participants (C), and female and male participants (D). Dots represent individual participant values; lines, mean Ct values; and shaded regions, 95% confidence intervals.
