The HPV vaccine provides effective protection against the human papillomavirus and the cancers it can cause. Because HPV is sexually transmitted, inclusion in mandatory vaccination schedules has been a controversial topic and laws vary by state. To further complicate matters, companies have continued to improve the vaccine, expanding the list of virus strains it protects against. A new study PNAS finds that having states require the latest, most protective HPV vaccine for girls and boys would be highly cost-effective and lead to better health outcomes on a national level.
HPV is the most common sexually transmitted infection in the US, with more than 100 viral strains circulating in the population. It is believed that more than half of cervical cancer cases in the US are caused by HPV, which can also cause vaginal cancer, penile cancer, anal cancer, and cancer of the mouth and throat.
Fortunately, several HPV vaccines are now available, including bivalent, quadrivalent, and non-valent — these protect against two, four, and nine strains of HPV, respectively. These vaccines can protect women against 66-81 percent of cervical cancer cases, depending on the number of strains included in the formulation.
Since states have drastically different recommendations regarding HPV vaccination, analyzing vaccination coverage and cost-benefit ratio can be challenging. Migration across state lines is also common, particularly in the years between vaccination, which occurs in adolescence, and disease onset, which occurs in early adulthood.
To study HPV vaccination and cervical cancer, a team of researchers developed a complex statistical model that took into account HPV infection, cervical cancer, vaccination coverage, and interstate migration for all 50 states and Washington DC. To approximate sexual intermingling and interactions, the researchers used data on the rate of partnership formation from the National Survey for Family Growth. In addition, they used a comparison of state-specific adolescent vaccination rates to determine the cost-effectiveness of new programs.
The researchers found that the 9-strain HPV vaccine would be significantly more effective at preventing cervical cancer cases and deaths than either of the less thorough versions. Based on their statistical analysis, they conclude that switching to the non-avalent HPV vaccine would have the same public health and economic benefit as increasing vaccination coverage by 11 percent, but would cost nearly $3 billion less.
If all states switch to the non-avalent HPV vaccine, state-specific health savings per capita could be as high as four dollars and forty cents. In addition, all states (not just those with vaccination programs) would see significant increases in residents’ quality-adjusted life years (QALYs). QALYs are a standard measure of the effectiveness of public health interventions, assessing the number of additional high-quality years of life an intervention provides.
The statistical analysis also showed that we would see greater benefits from increasing vaccination coverage in states that currently have lower rates compared to increasing rates in states that already vaccinate the majority of adolescents, due to the increase in herd immunity for states that currently have a low rate of vaccinations. vaccination rate.
Since interstate migration is likely to occur in the years between vaccination and cancer onset, the researchers argue that a nationally funded HPV vaccination campaign is likely to have the greatest impact. Much of the health and economic benefits of HPV vaccination will occur beyond a state’s borders, and this migration reduces states’ motivation to invest heavily in an HPV vaccination program. So federal involvement may be necessary to see the maximum benefit to public health and the economy.
The researchers write that a cohesive national vaccination plan using the nine-strain HPV vaccine would maximize economic and health benefits while limiting costs. However, this could prove to be a controversial recommendation, as some groups may find a federally orchestrated vaccination schedule for a sexually transmitted virus inappropriate.
Regardless of how it is arranged, teenagers within the vaccination window should be vaccinated with the non-avalent HPV vaccine before they are too old for vaccination. to CDC recommendations.
PNAS2016. DOI: 10.1073/pnas.1515528113 (About DOIs).