“Herd immunity” is a theory in immunology that holds that an entire population doesn’t need to get vaccinated against an infectious disease because once a significant portion of that population is vaccinated, even the un-vaccinated will be protected. As more and more people are vaccinated against an infectious disease such as polio, say, or measles, the chances of new infections among even the unprotected begin to fall.
Of course, the ideal is universal vaccination (who wants to take chances, right?). But as theorists of herd immunity propose, “in contagious diseases that are transmitted from individual to individual, chains of infection are likely to be disrupted when large numbers of a population are immune or less susceptible to disease” since there is less probability that an individual would come into contact with an infectious individual.
Herd immunity is one reason medical authorities now propose giving the anti-HPV vaccines to men and boys apart from women and girls. The HPV or human papillomavirus has been identified as causing over 80 percent of all cases of cervical cancer, a disease that afflicts only women. But as Dr. Ricardo Manalastas of UP-PGH pointed out in a talk at a recent Scientific Meeting of
AOGIN-Philippines, HPV, which Manalastas described as “ubiquitous” or common in humans, (it is also responsible for genital warts) has been implicated in other forms of cancer as well: penile and anal cancer and oral and oropharyngeal (mouth and throat) cancer among men; and vulvar and genital cancers among women.
But even if one were concerned only with cervical cancer, Manalastas points out that if men and boys were likewise vaccinated against HPV, then the chances of a woman being infected with HPV and risking cervical cancer (HPV is sexually transmitted) would fall as well. Vaccinated males would also in turn protect MSMs or men having sex with men, a side benefit.
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The good news is that HPV vaccination for men and boys has already been approved by the local Food and Drug Administration. There are currently two types of HPV vaccines: the bivalent, which protects against infection by the two most common cancer-causing types of HPV; and the quadrivalent, which protects not just against the two most common cancer-causing types, but also the two most common types that cause genital warts.
In the pipeline, says Manalastas, is the 9-valent vaccine, which protects against nine types of HPV (over 100 have been identified) implicated in cervical and other types of cancers, and in genital warts.
Now the bad news. HPV vaccines have been in the market in the Philippines for six years, and the two drug companies marketing the two types of vaccines have embarked on extensive and energetic marketing efforts, tapping the services of celebrity endorsers, coming up with emotionally engaging ads and sponsoring various outreach programs to bring the benefits of vaccination even to those who can scarcely afford it. But after all these, says Manalastas, “only one percent of the eligible population has been reached.”
To make an impact in the battle against cervical cancer, says the doctor, “we need to cover 70 percent of the population.” In other words, he says, “we need to do better!”
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It doesn’t take too much intellectual or scientific calisthenics to come up with a reason for the dismal reach of the HPV vaccine. The reason is obvious: cost. Currently, the three doses (via injection) of the vaccine costs a total of P12,000—not an amount to sneeze at, but certainly cheaper than the latest models of smart phones, iPads or iPods.
“My dream,” Manalastas says, “is a workplace- or school-based, national government-funded vaccination program.” This is the program currently in place in Australia, where the vaccine was developed, and that nation, he says, “has seen a dramatic decrease in genital warts in men and women.” Warts, he points out, make for a practical (and visible) marker to indicate possible prevalence of cervical and other HPV-caused cancers.
The current situation of very limited reach for the HPV vaccine echoes that of screening procedures for cervical cancer. Before the development of alternative screening, the “gold standard” was the pap smear, which was minimal in cost although it required analysis by a pathologist working out of a lab. Despite decades of experience, only one percent of the female population was getting screened, including those who were getting yearly smears.
With the development of VIA, or visual inspection with ascetic acid, and the one-stop approach of screening and treatment (by cryotherapy or freezing of suspicious-looking tissue), the cost of screening has been lowered considerably. But still health advocates are struggling to reach enough women, especially those in hard-to-reach areas. Currently being tried out is the “mother-daughter approach,” which calls for reaching out to older women to get screened, while convincing their daughters to go for vaccination.
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Manalastas is worried. The history of vaccination—or rather, the speed at which the population and government respond to it in this country—is not very promising. “It took us a total of 25 years before the Hepa-B vaccine (the only other vaccine besides the HPV vaccine which protects against a form of cancer, this time liver cancer) became part of the expanded program of immunization,” he points out. Are we willing to wait for 25 more years before the HPV vaccine becomes routine, available and accessible to every Filipino girl and boy? Or are we willing to watch them die from an entirely and easily preventable disease?