Human papillomavirus infection in Bhutan at the moment of implementation of a national HPV vaccination programme

Abstract

Background: Cervical cancer is the most common female cancer in Bhutan, the first low/middle-income country to implement a national human papillomavirus (HPV) vaccination programme.

Methods: To provide a robust baseline for future evaluations of vaccine effectiveness, cervical cell specimens were obtained from 2,505 women aged 18-69 years from the general population, and biopsies from 211 cervical intraepithelial neoplasia grade 3 (CIN3) and 112 invasive cervical cancer (ICC) cases. Samples were tested for HPV using GP5+/6+ PCR.

Results: Among the general population, HPV prevalence was 26%, being highest (33%) in women ≤24 years, but remaining above 15% in all age-groups. Determinants of HPV included age, marital status, and number of sexual partners. Among the eight percent with cytological abnormalities, 24 CIN3 and 4 ICC were histologically confirmed. Even after additional testing with a sensitive E7 PCR, no infections with vaccine-targeted HPV types were detected in the few vaccinated women (n = 34) compared to 6% prevalence in unvaccinated women of similar age (p = 0 · 215).

Conclusion: Based upon type-specific prevalence among biopsies, at least 70% of ICC in Bhutan are theoretically preventable by HPV16/18 vaccination, but screening programmes should be expanded among older women, who have an important underlying burden of CIN3 and ICC.

Figure 1

Age-specific prevalence of human papillomavirus (HPV) DNA and of cytological abnormalities among 2,505 women. Bhutan, 2011–2012. HPV = human papillomavirus.

Figure 2

Age-specific prevalence of human papillomavirus (HPV) DNA among 885 women ≤24 years old, according to two HPV DNA tests (GP5+/6+ and multiplex E7). Bhutan, 2011–2012. HPV = human papillomavirus; HR = high-risk.