High-income countries that initiated widespread administration of the Human Papilloma Virus (HPV) vaccine in the mid-2000s have experienced substantial declines in cervical cancer cases, marking a significant achievement in medicine. A new study in The Lancet by researchers at Queen Mary University of London (Queen Mary) suggests this vaccine may also be responsible for a near-complete protective effect against death from cervical cancer among women under 30 in England who received the vaccine between 12-18 years old—one of few analyses of the HPV vaccine's effect on mortality.
The findings by Queen Mary researchers Peter Sasieni and Milena Falcaro provide compelling evidence that HPV vaccination is a highly effective cancer prevention strategy, but more data is needed to confirm a direct cause-and-effect link to declines in cervical cancer mortality, writes Dr. Allison Portnoy , assistant professor of global health at Boston University School of Public Health (BUSPH), in an invited commentary also published in The Lancet.
"The study makes an important contribution to the literature on the population-level impact of HPV vaccination by connecting mortality data and HPV vaccine coverage data, but these are indeed population-level rather than individual-level data," writes Dr. Portnoy, whose research focuses on the public health, economic , and equity effects of vaccination and vaccine policy.
Specifically, the study found that cervical cancer deaths declined by 80 percent in 2015-2019, and no deaths were recorded between 2020-2024, among 20-24-year-olds who received the vaccine between 12-18 years old. Research has indeed determined causal links between the HPV vaccine and prevention of precancerous cells (high-grade cervical intraepithelial neoplasia) that can lead to cervical cancer and death, Dr. Portnoy notes, but cautions that other factors that may have contributed to the sharp decline in mortality identified in the study. Improvements in and expansion of cervical cancer screening, as well as increased HPV vaccination, may have been instrumental in the observed mortality decline. Herd immunity may have also played a role, she writes, as people who received HPV vaccination are less likely to transmit HPV to other unvaccinated individuals.
According to the World Health Organization (WHO), HPV is the most common sexually transmitted infection, and it includes more than 200 known types. The majority of people who become infected with HPV do not display any symptoms and the infection usually clears on its own, but certain high-risk strains can lead to persistent infections and several types of cancer, and these strains cause almost all cervical cancer diagnoses. Almost all cervical cancer diagnoses are thought to be caused by the virus. National HPV vaccination programs focused on adolescent girls in the mid-2000s because the primary goal was to prevent cervical cancer, but programs now also promote vaccination to young males, who may also be susceptible to HPV attributable cancers that affect males such as oropharyngeal, anal, and penile. England's school-based program led to a 90-percent drop in HPV infections among adolescents, putting the country closer to its goal to eliminate cervical cancer as a public health problem by 2040.
HPV vaccination and cervical cancer data that will continue to emerge could provide detailed insight into individual-level HPV and cervical cancer diagnoses and outcomes, Dr. Portnoy writes. "Additionally, because vaccinated cohorts are still relatively young, continued and longer-term follow-up will be important to assess whether these reductions persist into older ages when cervical cancer mortality risk is higher and when different HPV genotypes might contribute to the burden differentially by age."
For now, the population-level findings in the study underscore the importance of countries' continued investment in national vaccination programs and cancer screenings, as well as the need to vaccinate early in adolescence, Dr. Portnoy writes. Without concerted investment in these preventive measures, inequities in access to the HPV vaccine will continue to widen, especially in low-income countries, where HPV rates are highest, she adds.
"The findings from England therefore provide an important benchmark for what could be achievable when high vaccination coverage is sustained over time, but [realizing] similar gains globally will require intentional implementation and delivery strategies to mitigate inequalities in cervical cancer burden," writes Dr. Portnoy. "… As vaccinated cohorts age and countries gather longer-term follow-up data, the next step will be ensuring that these gains are achieved equitably through sustained vaccination, screening, and treatment infrastructure capable of supporting the WHO strategy for cervical cancer elimination."
