Number of primiparous women required for a double blinded postnatal efficacy trial on preventive HPV16 vaccination with the second pregnancy as the end point
| Number of vaccinees at a given vaccine efficacy | |||
|---|---|---|---|
| Age group (years) | HPV16 attack rate* (%) | 90% | 70% |
| *Between the first and the second pregnancy. | |||
| ≤17 | 13.8 | 142 | 274 |
| 18–19 | 7.0 | 292 | 566 |
| 21 | 2.3 | 914 | 1782 |
| 23 | 2.4 | 876 | 1706 |
| 25 | 1.3 | 1626 | 3176 |
| <25 | 4.5 | 460 | 898 |