Studies that examined the influence of HPV vaccination on pregnancy and STI rates among young females
| STUDY* | COUNTRY | DESIGN | PARTICIPANT CHARACTERISTICS | OUTCOMES | |
|---|---|---|---|---|---|
| PREGNANCY | STI | ||||
| Smith et al,3 2015 | Canada | 6 population-based administrative databases | Age 13–17 y; 128 712 vaccinated and 131 781 unvaccinated | No evidence that vaccination increased the risk of composite end point: RR = 0.96, 95% CI 0.81 to 1.14 | |
| Bednarczyk et al,9 2012 | United States | Cohort study using medical records | Vaccinated at age 10–12 y; 493 vaccinated and 905 unvaccinated | Risk of composite end point not elevated: IRD = 1.6, 95% CI −0.03 to 2.24, per 100 PY | |
| No difference in pregnancy diagnosis: IRD = 0.07, 95% CI −0.20 to 0.35, per 100 PY | No difference in diagnosis of Chlamydia trachomatis: IRD = 0.06, 95% CI −0.30 to 0.18 | ||||
| Liddon et al,10 2012 | United States | Data from the National Survey of Family Growth | Age 15–24 y; 279 vaccinated and 964 unvaccinated | NA | No difference in receiving STI service in past year among those aged 15–19 y (38.7% [95% CI 27.7% to 51.0%] vs 28.9% [95% CI 23.3% to 35.2%]) |
| Rysavy et al,11 2014 | United States | Cross-sectional survey, using assisted interviews | Age 13–23 y; 153 vaccinated and 70 unvaccinated | Not being vaccinated was associated with pregnancy (20% vs 9%, P = .016) | No difference in the proportion of C trachomatis, gonorrhea, genital herpes, syphilis, pubic lice, HIV, genital warts, HPV, trichomoniasis, and hepatitis B infections between vaccinated and unvaccinated participants |
| Kumakech et al,12 2017 | Uganda | Population-based comparative cross- sectional survey | Age 15–24 y (median age was 18.6 y); 438 females (53% of whom were vaccinated) | NA | No statistically significant difference between vaccinated and unvaccinated participants regarding the history of STD syndrome and the prevalence of syphilis and HIV infections |
| Jena et al,13 2015 | United States | Insurance claim database | Age 12–18 y; 21 610 vaccinated and 186 501 unvaccinated | NA | HPV vaccination was not associated with an increase in STIs: OR = 1.05, 95% CI 0.80 to 1.35 |
| Cummings et al,14 2012 | United States | Comparison of a group of vaccinated adolescent girls with historical controls. Questionnaires and clinician- or self- collected vaginal swabs | Age 14–17 y; 75 vaccinated and 150 matched unvaccinated | NA | No differences in diagnoses for C trachomatis and Trichomonas infections between vaccinated and unvaccinated adolescent girls: OR = 0.9, 95% CI 0.04 to 2.20, and OR = 5.3, 95% CI 0.7 to 42.3, respectively |
| Sadler et al,15 2015 | United Kingdom | Clinical histories from genitourinary medicine clinic visitors | Age 14–20 y; 231 vaccinated and 132 unvaccinated | NA | Not being vaccinated was positively associated with receiving C trachomatis diagnosis: OR = 2.30, 95% CI 1.06 to 5.00 |
HPV—human papillomavirus, IRD—incidence rate difference, NA—not applicable, OR—odds ratio, PY—person-years, RR—relative risk, STD—sexually transmitted disease, STI—sexually transmitted infection.
↵* Only studies including some participants younger than 18 years of age were included in this table. Studies including only adults were not included in this review.