Table 2.

The mean copy numbers of virus RNA markers (mean ± standard deviation, log₁₀ copies 100 ml⁻¹) detected with SARS betacoronavirus E-Sarbeco, SARS-CoV-2 N2 and norovirus GII assays in Viikinmäki WWTP influent wastewater sample taken 19–20 April 2020 and stored over 84 days at 4 °C, −20 °C, and −75 °C. The analysis at each time and temperature point was performed from triplicate aliquots. The number of replicates with results above the quantification limit (LOQ) are shown in parenthesis.

Target	Sample fraction	Storage time (days)	RNA copy number at storage temperatures			Quantification frequency (number of aliquots)
			4 °C	−20 °C	−75 °C
SARS E-Sarbeco	Supernatant	29	2.6 ± 0.2 (2)	< LOQ (0)	2.4 (1)
		64	3.1 ± 0.2 (3)	2.8 ± 0.2 (3)	2.8 ± 0.0 (2)
		84	2.9 ± 0.3 (2)	2.5 (1)	2.8 ± 0.3 (2)
	Total mean ± SE (95% CI): 2.8 ± 0.1					Supernatant: 16/27 (59%)
	Pelleta	84	3.4 ± 0.2 (3)	2.8 ± 0.5 (2)	3.3 ± 0.0 (2)
	Total mean ± SE (95% CI): 3.2 ± 0.2					Pellet: 7/9 (78%)
SARS-CoV-2 N2	Supernatant	29	3.7 ± 0.1 (2)	3.5 (1)	3.6 ± 0.1 (2)
		64	3.7 ± 0.2 (3)	3.7 ± 0.1 (2)	3.7 ± 0.1 (2)
		84	3.7 ± 0.2 (2)	3.4 (1)	3.6 ± 0.2 (3)
	Total mean ± SE (95% CI): 3.6 ± 0.1					Supernatant: 18/27 (67%)
	Pelleta	84	4.2 ± 0.1 (3)	3.9 ± 0.1 (2)	3.9 ± 0.4 (3)
	Total mean ± SE (95% CI): 4.0 ± 0.2					Pellet: 8/9 (89%)
Norovirus GII	Supernatant	29	4.4 ± 0.2 (3)	4.8 ± 0.1 (3)	4.8 ± 0.1 (3)
		64	3.7 ± 0.1 (3)	3.7 ± 0.1 (3)	3.8 ± 0.0 (3)
		84	3.5 ± 0.1 (3)	3.6 ± 0.3 (3)	3.7 ± 0.1 (3)
	Total mean ± SE (95% CI): 4.0 ± 0.2					Supernatant: 27/27 (100%)
	Pelleta	84	3.8 ± 0.2 (3)	3.0 ± 0.1 (2)	3.0 ± 0.1 (3)
	Total mean ± SE (95% CI): 3.3 ± 0.3					Pellet: 8/9 (89%)

^aThe analysis is performed for the particulate fraction (i.e., pellets from pre-centrifugation). SE = standard error, CI = confidence interval.