Table 1.

Summary of the viral load data used for modeling

Country	Number of data	Reporting unit	Specimens for measuring viral load	Date of collection	Source
Symptomatic
USA	$33$	viral load (copies/mL)	Nares and oropharyngeal swabs	Nov 2020 to May 2021	ref. 44
USA	$12$	viral load (copies/mL)	Nares and oropharyngeal swabs	Nov 2020 to May 2021	ref. 26
Germany	$8$	viral load (copies/swab)b	Pharyngeal swab	Jan 2020	ref. 19
Korea	$34$	cycle thresholda	Oro/nasopharyngeal swabs	May 2020	ref. 45
Korea	$2$	cycle thresholda	Oro/nasopharyngeal swab	Feb 2020	ref. 46
Singapore	$12$	cycle thresholda	Nasopharyngeal swab	Jan to Feb 2020	ref. 47
China	$8$	cycle thresholda	Nasal swab	Jan 2020	ref. 48
Asymptomatic
USA	$44$	viral load (copies/mL)	Nares and oropharyngeal swabs	Nov 2020 to May 2021	ref. 44
USA	$28$	viral load (copies/mL)	Nares and oropharyngeal swab	Nov 2020 to May 2021	ref. 26
Japan	$18$	cycle thresholda	Nasopharyngeal or throat swab	Jan 2020	ref. 49
Korea	$4$	cycle thresholda	Nasal and throat swabs	Feb to Apr 2020	ref. 50
Singapore	$7$	cycle thresholda	Nasopharyngeal swab	Mar to Apr 2020	ref. 51

^aViral load was calculated from cycle threshold values using the conversion formula: ${\log }_{10}\left(\mathrm{Viral\; load}\left[\mathrm{copies}/\mathrm{mL}\right]\right)=-0.32\times \mathrm{Ct\; values}\left[\mathrm{cycles}\right]+14.11$²².

^b1 swab = 3 mL.