Towards cervical cancer elimination through HPV vaccination in Bhutan

Cervical cancer is caused by infection with carcinogenic types of human papillomavirus (HPV), also known as high-risk HPV types. Infection with the most frequently occurring and carcinogenic HPV types can be controlled through targeted vaccination, which has been widely introduced in high-income countries but is still poorly adopted in low- and middle-income countries. To mark Cervical Cancer Awareness Month, the International Agency for Research on Cancer (IARC) is highlighting some of its research projects to tackle the global burden of this cancer type.

In 2010, Bhutan launched an HPV vaccination programme. Girls aged 12–18 years were offered vaccination against four of the most common and carcinogenic HPV types. The campaign was a resounding success, with reported initial coverage reaching about 90% of girls in the target age group.

Researchers from IARC and the Ministry of Health of Bhutan are performing long-term field studies, embedded in the local health-care systems, to provide real-time evaluation of the impact of HPV vaccination in the country and to inform future local cervical cancer control policies.

IARC scientists compared HPV prevalence in women aged 17–29 years from data gathered in 2011–2012 with HPV prevalence in women from data gathered in 2018. They showed that in Thimphu, the capital of Bhutan, the prevalence of HPV types targeted by the vaccine decreased by 93% during this period. Furthermore, unvaccinated women also benefited from the reduced HPV transmission in the community: in this group, the prevalence of vaccine-targeted HPV types decreased by 88%.

Reductions in cancer incidence as a result of any public health intervention often take decades to manifest, because cancers typically occur a long time after the exposure to carcinogenic agents, such as HPV. Tracking reductions in cancer rates can be even more challenging in low- and middle-income countries, because proving the effect requires well-maintained population-based cancer registries, which are often lacking in these settings.

This study by IARC scientists is important because, although a direct effect of HPV vaccination on cervical cancer rates may not be measurable for many years, the observed reduction in HPV prevalence unequivocally shows that vaccination programmes can be successful, and this can galvanize both public and institutional support for HPV vaccination programmes.

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Visit the Cervical Cancer Awareness Month 2022 webpage