trendless, > By both Ct value and antigen concentration measurements, median viral loads rose from the day of symptom onset and peaked on the fourth/fifth day. Ag RDT sensitivity estimates were 30.0-60.0% on the first day, 59.2-74.8% on the third day, and 80.0-93.3% on the fourth day of symptoms.
> In 74 influenza A PCR-positive individuals (55.4% women; median 35.0y), median influenza viral loads peaked on the second day of symptoms.
> In a highly immune adult population, median SARS-CoV-2 viral loads peaked around the fourth day of symptoms. Influenza A viral loads peaked soon after symptom onset. These findings have implications for ongoing use of Ag RDTs for COVID-19 and influenza.
https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciad582/7285011