Table 1.
Socio-demographic characteristics of the female participants (birth cohort 2001) per sampling moment.
| Study round (time since vaccination) | R1 (Mo 1) |
R2 (Mo 6) | R3 (Y 1.5) |
R4 (Y 2.5) |
R5 (Y 3.5) |
R6 (Y 4.5) |
R7 (Y 5.5) |
R8 (Y 6.5) |
R9 (Y 7.5) |
|---|---|---|---|---|---|---|---|---|---|
| Participation (n = 56) complete | 55 | 54 | 52 | 45 | 47 | 47 | 30 | 32 | 31 |
| Blood only | 0 | 0 | 1 | 3 | 2 | 1 | 1 | 4 | 2 |
| Questionnaire only | 0 | 1 | 2 | 0 | 1 | 1 | 10 | 1 | 2 |
| Calendar year | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 |
| Age (median, range) | 13, 12-13 |
13, 13-14 |
14, 14-15 |
15, 15-16 |
16, 16-17 |
17, 17-18 |
18, 18-19 |
19, 19-20 |
20, 20-21 |
| Ethnicity (% Dutch) | 48 (81.4) | 48 (81.4) | 48 (81.4) | 41 (91.1) | 39 (90.8) | 37 (90.3) | 33 (91.7) | 27 (93.1) | 23 (95.8) |
| Current educational level* | |||||||||
| High | 29 (52.7) | 29 (52.7) | 29 (53.7) | 22 (48.9) | 25 (52.1) | 25 (56.8) | 18 (51.4) | 20 (69.0) | 22 (75.9) |
| Middle | 18 (32.7) | 20 (36.4) | 21 (38.9) | 18 (40.0) | 19 (39.6) | 19 (43.2) | 17 (48.6) | 9 (31.0) |
7 (24.1) |
| Low | 8 (14.6) | 6 (10.9) | 4 (7.4) | 5 (11.1) | 4 (8.3) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| Ever had sex (% yes) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
5 (11.1) |
12 (25.0) | 18 (38.3) | 24 (60.0) | 23 (69.7) | 26 (78.8) |
| Age sexual debut among sexually active participants (median, range) | N/A | N/A | N/A | 15, 14-15 | 15, 15-16 | 16, 14-17 | 16, 14-19 | 16, 13-19 | 17, 15-20 |
| Ever used contraception (% yes) | 4 (7.3) |
5 (9.0) |
9 (16.7) |
17 (37.8) | 26 (53.1) | 32 (66.7) | 30 (76.9) | 29 (82.9) | 29 (93.6) |
| Underlying illness (% yes) | 2 (3.6) | 3 (5.5) | 4 (7.4) | 2 (4.4) | 5 (10.4) | 5 (10.4) | 2 (5.0) | 2 (6.1) | 3 (9.1) |
| Immunosuppressive medication (% yes) | 1 (1.9) | 0 (0.0) | 0 (0.0) | 1 (2.3) | 0 (0.0) | 2 (4.3) | 0 (0.0) | 0 (0.0) | 2 (6.3) |
| Had menarche (% yes) | 39 (70.9) | 46 (83.6) | 51 (94.4) | 45 (100) | 48 (100) | 48 (100) | 40 (100) | 33 (100) | 33 (100) |
Mo, Month; Y, Year; N/A, Not applicable.
* Low = primary or lower general vocational secondary education; Middle = intermediate vocational secondary education; High = higher vocational/general secondary education, (pre)university education.