Table 3.

Association between C_T value and natural log(n+1) transformed antigen concentration (pg/ml), variant, vaccine status, and presence of symptoms for 151 Delta and 168 Omicron samples, excluding samples with missing information on days since last vaccine or symptom duration.

	Base Model			Full Model
Variable	Beta	SE	p-value	Beta	SE	p-value
Log (Antigen Concentration + 1)	−2.3	0.079	<0.001	−2.2	0.080	<0.001
Variant
Delta	Ref	—		Ref	—
Omicron	−6.8	0.546	<0.001	−6.5	0.569	<0.001
Vaccine Status
Not Fully Vaccinated				Ref	—
Fully Vaccinated				0.75	1.34	0.6
Presence of Symptoms
Asymptomatic				Ref	—
Symptomatic				−8.0	2.19	<0.001
Days Since Last Vaccine
Unvaccinated				Ref	—
Within the Last 90 Days				0.23	1.31	0.9
Between 91 and 180 Days Ago				−0.10	1.53	>0.9
Between 181 and 270 Days Ago				−0.57	1.49	0.7
More than 270 Days Ago				0.86	1.85	0.6

SE = Standard Error, Ref = Reference Level

NOTE: Beta coefficients have been rounded but percentage change calculations were computed before rounding and therefore may be different.