Table 2. Overall mean estimates from quantitative and qualitative assays of HEV samples in study to establish a WHO International Standard for HEV RNA NAT-based assays*.
| Assay type and sample | No. | Mean (95% CI)† | SD | % CV |
|---|---|---|---|---|
| Quantitative | ||||
| 1 | 123 | 5.58 (5.32–5.85) | 0.54 | 98 |
| 2 | 125 | 5.60 (5.33–5.87) | 0.53 | 94 |
| 1 + 2 | 248 | 5.59 (5.33–5.86) | 0.55 | 99 |
| 3 | 124 | 5.66 (5.40–5.93) | 0.45 | 77 |
| 4 | 125 | 5.66 (5.40–5.93) | 0.44 | 76 |
| 3 + 4 |
249 |
5.66 (5.40–5.93) |
0.44 |
76 |
| Qualitative | ||||
| 1 | 19 | 5.25 (5.01–5.50) | 0.51 | 150 |
| 2 | 20 | 5.26 (4.97–5.56) | 0.62 | 179 |
| 1 + 2 | 39 | 5.26 (5.08–5.44) | 0.56 | 163 |
| 3 | 20 | 5.27 (4.90–5.64) | 0.79 | 226 |
| 4 | 20 | 5.31 (5.02–5.61) | 0.64 | 183 |
| 3 + 4 | 40 | 5.29 (5.07–5.52) | 0.71 | 202 |
*Samples 1 and 2, replicate samples of the candidate WHO International Standard; samples 3 and 4, replicate samples of the candidate Japanese national standard. HEV, hepatitis E virus; WHO, World Health Organization; NAT, nucleic acid amplification technique; no., no. dilutions analyzed (in linear range for quantitative assays); % CV, geometric coefficient of variation. †Values are log10 copies/mL for quantitative and log10 NAT–detectable units/mL for qualitative assays.