Type of control	Result interpretation
Sample	Negative control	Should be negative
Positive control	Should be positive
Negative sample	Sample is negative if each Ct value is undetectable for GI/GII
Positive sample	Ct values (GI/GII) of both replicates is < 38; this (arbitrarily) cut-off needs to be determined experimentally for each realtime PCR platform and kit
Tentative positive sample	Sample is tentatively positive if Ct value (GI/GII) of one replicate is <38
Internal process control (MS2)	Samples with a threshold cycle (Ct) value of ≥32 for MS2 should be retested undiluted and 1/10 diluted.
	Parameter	Acceptable value
Standard curve using norovirus RNA transcripts	R2	>0.97
Efficiency	90% to 115%