By Zsombor Gal
In 2018, the World Health Organization counted nearly 570,000 new cases of cervical cancer in addition to 310,000 deaths worldwide. Roughly 90% of these deaths occurred in low- and middle-income countries, where screening and treatment programs are not as readily available as in developed nations. Though it may be surprising, prevention of cervical cancer through vaccination has only recently been viewed as a comprehensive solution to this global health crisis.
21st century innovation provided the first vaccine specifically approved for the prevention of cancer. In 2006, the U.S. Food and Drug Administration approved a vaccine developed by Merck & Co. to prevent human papillomavirus (HPV) infection. The tetravalent vaccine, known as Gardasil, protects against four HPV strains known to cause cervical, anal, vulvar, vaginal, and penile cancers. More recently, Gardasil 9 was approved to protect against five additional HPV strains associated with cervical cancer. These vaccines contain virus-like particles, which consist of self-assembled HPV capsid proteins, but lack the viral DNA. Thus, the vaccine enables the recipient to produce antibodies against HPV virions while preventing the production of harmful viral proteins that are responsible for disease. HPV is an example of a transforming virus, in that it encodes proteins that inactivate tumor suppressor proteins within human cells. This causes the rapid proliferation of cells, leading to tumor formation. Hence, as HPV is the most common sexually transmitted infection, not only in the United States but globally, it represents a serious threat to human health.
Not everyone infected with HPV will develop cancer. In fact, HPV is typically cleared by the immune system or simply causes precancerous lesions such as skin warts. However, exposure to high-risk HPV strains or long-lasting infectious greatly increases the risk for cancers caused by HPV. Because the risk of death due to these cancers is exceptionally high, it is important that all children and adolescents receive the vaccine prior to becoming sexually active.
However, this has unfortunately not been the case. In 2017, the Centers for Disease Control and Prevention reported that only 49 percent of adolescents in the United States are up to date on HPV vaccination. Many developing nations fall short of this statistic or have only recently introduced countrywide vaccination programs. The reasons for low vaccination rates encompass a variety of factors, including awareness, healthcare accessibility, cost, and misguided parental decisions.
Cancer-causing viruses are not a recent discovery, but public awareness of genital and oropharyngeal cancers caused by HPV is strikingly low. Additionally, because HPV is typically diagnosed in sexually active adults, many pediatricians are either unaware of the cancer risk or unwilling to discuss sex with the parents of younger children. The HPV vaccine may be suffering from an “image problem,” as it is often portrayed as a sexually transmitted disease vaccine, not as a cancer prevention vaccine. This contributes to parental anxieties that receiving the vaccine may encourage sexual promiscuity at a young age.
Poor access to healthcare and infrequent medical check-ups also contribute to low vaccination rates. Citizens of developing nations and minority populations face difficulties in obtaining regular care by a physician at all and thus have lower vaccination rates overall. Further complicating the matter is the fact that the HPV vaccine is rather expensive. Those without health insurance can expect to pay $250 dollars per dose for Gardasil in the United States, which consists of three doses!
The HPV vaccine clearly needs a rebranding. As the world’s first vaccine against cancer, and perhaps the simplest form of cancer prevention aside from lifestyle change, it seems illogical that parents should reject vaccination for their children. Initiatives must be put into place to serve populations without reliable and inexpensive access to healthcare, as well as in developing nations with high incidences of HPV infection. There is hope: leaders in these countries may choose to follow the example of Rwanda, a sub-Saharan nation that has achieved 93% vaccination coverage. Rwandan leaders combined the expertise and influence of state agencies, infectious disease entities, and international vaccine providers to reach a substantial portion of the population within a short period of time. The elimination of preventable cancers such as HPV would be a major milestone in the history of medicine.