TABLE 3.

Limit of detection in DBS of the TaqMan HIV-1 Qualitative Test, v2.0, using the 2nd International HIV-1 RNA WHO Standard, NIBSC code 97/65041, HIV-1 subtype B, diluted in HIV-1-negative whole blood for DBS^a

Nominal input (HIV-1 RNA cp/ml)	No. of replicates	No. of positives	Positivity rate (%)
500	189	189	100
400	187	185	99
300	188	183	97
150	188	166	88
75	188	108	57
0	188	0	0

^aOne copy of HIV-1 RNA is equivalent to 1.7 ± 0.1 IU. Probit analysis showed a 95% hit rate of 221.8 cp/ml (95% confidence interval, 195.6 to 260.5 cp/ml).