Cervical Cancer Prevention: Is One Dose of the HPV Vaccine Enough? | Kathleen M. Schmeler, MD

Kathleen Schmeler, MD

During the World Health Assembly in May 2023, WHO Director-General Tedros Adhanom Ghebreyesus, PhD, MSc, commented on advancements in global efforts to eliminate cervical cancer, stating in his opening remarks that “vaccines are bringing the dream of eliminating cervical cancer within reach.” Kathleen M. Schmeler, MD, shares information about studies on single-dose vaccinations and the possibilities this approach offers to realize cervical cancer elimination.

Cervical cancer is the fourth most common cancer in women worldwide with an estimated annual incidence of 604,000 cases and 341,000 related deaths globally. Over 85% of these cases and deaths occur in low- and middle-income countries (LMICs), primarily due to a lack of organized vaccination, screening, early detection, and treatment programs. In addition, some medically underserved regions of the US also have high rates of cervical cancer. For example, the Rio Grande Valley (RGV) along the Texas–Mexico border has cervical cancer incidence and mortality rates approximately 25% higher than the rest of the state, and 55% higher compared with the rest of the US.

To address these growing disparities in cervical cancer incidence and mortality between high-and low-resource areas, the World Health Organization (WHO), with endorsement from over 194 countries, launched a global initiative to accelerate the elimination of cervical cancer as a public health problem. The targets for this initiative include: (1) 90% of girls worldwide receive the HPV vaccine by the age of 15; (2) 70% coverage of screening using a high-performance test at the ages of 35 and 45; and (3) 90% of women with pre-invasive/invasive cervical disease receive treatment.

The HPV vaccine shows great promise and was first introduced in the US in 2006. Despite limited uptake, the HPV vaccine has already led to a notable drop in cervical cancer cases and deaths among the first American generation to get vaccinated. Among women ages 20 to 24, cervical cancer rates declined by 65% from 2012 to 2019. In most high-income countries, including the US, the vaccine is given in a series of two or three shots beginning as early as age 9; however, a large number of countries have not successfully introduced the vaccine due to cost and the implementation challenges of multiple doses.

Fortunately, there is increasing evidence that a single dose of the HPV vaccine may be enough. In 2022, the WHO changed their recommendations to a single HPV dose for those age 9 to 20 years and two doses (six months apart) for those age 21 and older. Several countries including Australia, the UK and Ireland have already adopted these new guidelines. This approach is further supported by the recent results of the KEN-SHEE study, a randomized controlled trial in Kenya, which showed a single HPV dose to have an efficacy of 97.5% at 1.5 years and to be comparable to multi-dose regimens 24 and 30 months after vaccination. The results of this study and others supporting a single dose could be a game-changer. Transitioning the HPV vaccination to a single dose could alleviate many barriers and move towards the elimination of cervical cancer in LMICs and here at home in the U.S.

Kathleen Schmeler, MD, is a Professor in the Department of Gynecologic Oncology and Reproductive Medicine at MD Anderson Cancer Center in Houston, Texas. She provides surgical care and chemotherapy to women with gynecologic malignancies.