The HPV vaccine prevents cancer, but most kids don’t receive it

The human papillomavirus vaccine can prevent six potentially lethal malignancies, but inoculation is meeting with rising resistance from parents. (Photo: NYTimes)
Vaccine hesitancy is hardly limited to shots against COVID-19. Even the HPV vaccine, which can prevent as many as 90 percent of six potentially lethal cancers, is meeting with rising resistance from parents who must give their approval before their adolescent children can receive it.اضافة اعلان

The Food and Drug Administration licensed this lifesaving vaccine in 2006 to protect against sexually transmitted infection by HPV, the human papillomavirus. Most of us will get infected with HPV during our lifetimes, certain strains of which can lead to cancers of the cervix, vagina and vulva in women; cancers of the anus and back-of-the-throat in both women and men; and penile cancer in men. HPV can also cause genital warts.

But the vaccine only works if it’s administered before people become infected by the virus. And that often means getting vaccinated before teens and young adults have any form of sexual activity.

Unless they are vaccinated, more than 80 percent of women become infected with HPV by age 50. And while most infections clear on their own, enough persist to cause many thousands of cancers years later. There is no treatment for an HPV infection.

Yet Kalyani Sonawane, a researcher at the University of Texas Health Science Center, and her colleagues reported in March that parental intent not to vaccinate their adolescents against HPV rose from 50.4 percent in 2012 to 64 percent in 2018. Many parents resisted the vaccine despite their doctors’ recommendations, Sonawane said. Ironically, parents were most resistant — at 68.1 percent — to vaccinating girls, the very group for whom this vaccine was initially developed to prevent cervical cancer.

Now, if not for the slow adoption of the HPV vaccine by the parents of adolescents, we would likely be well on our way to eliminating nearly all cases of cervical cancer and the five other HPV-caused cancers, 45,000 cases of which are diagnosed annually in the US, Dr. Abraham Aragones, a public health researcher at Memorial-Sloan Kettering Cancer Center told me.

A highly effective vaccine

Until recently, the vaccine’s ability to prevent cancer was presumed but not proved. Cervical cancer risk rises with age, most often occurring in midlife or later, so it can take many years to confirm the vaccine’s ability to protect against cancer.

Now a new study in Britain of an early version of the vaccine found that within 13 years of vaccine administration, there were 87 percent fewer cases of cervical cancer among young women immunized between ages 12 and 13, compared to unvaccinated women. Significantly lower cancer rates were also found among women immunized between ages 14 and 16 and between 16 and 18, although the greatest benefit occurred among those vaccinated at the youngest ages, before most girls were likely exposed to the virus through sexual contact.

(Illustration : Envato-Elements)

The British study involved a vaccine called Cervarix that protects against two variants of the virus. The current US version of the HPV vaccine, called Gardasil-9, is even more effective: It protects against nine variants of the virus and is expected to prevent more than 90 percent of HPV-related cancers, Aragones said. A recent analysis in JAMA Pediatrics found a similar decrease in cervical cancer incidence and mortality in young women since the vaccine was introduced.

Based on a steadily declining incidence of cervical cancer and a high rate of vaccine coverage in Australia, researchers there predicted that the country would have fewer than four new cases of cervical cancer per 100,000 women by 2028 and virtually none by 2066.

To be sure, regular Pap smears that detect precancerous cervical lesions have helped greatly to prevent the development of invasive cancer, but early detection efforts do not fully eliminate the risk of cervical cancer. This year, the American Cancer Society estimates that 14,480 new cases of invasive cervical cancer will be diagnosed in the US and about 4,290 women will die from it. And there is no screening test like the Pap smear for the other five HPV-caused cancers.

Parents’ buy-in remains the biggest obstacle

Once the real cancer culprit was identified as the human papillomavirus and a vaccine to prevent it finally developed, persuading parents to have their young daughters immunized has been an uphill battle for practitioners. Few have the time and factual ammunition to counter parental fears and misinformation about this vaccine.

Getting parents to agree to immunizing boys has faced an additional obstacle. The original approval of the vaccine to prevent cervical cancer prompted many parents to question its value for boys, for whom the vaccine was approved three years later. Parental resistance to immunizing their sons rose to 59.2 percent in 2018, up from 44.4 percent just six years earlier

“Parents and providers don’t necessarily appreciate the burden of HPV-caused cancers among men,” said Dr. Dean A. Blumberg, chief of pediatrics at UC Davis Children’s Hospital. “Oral-pharyngeal cancer rates are almost five times higher in men than in women, and they’ve increased in recent years with the rise in oral sex. The vaccine is important for the boys to protect their own health and the health of their future partners.”

(Illustration : Envato-Elements)

How the vaccine is administered

Between ages 9 and 15, two shots of HPV vaccine are required, administered six months apart; from age 15 on, three shots are needed. Side effects are usually mild, like pain or swelling at the injection site and perhaps brief fever, fatigue, nausea or muscle pain. The vaccine’s cost is nearly always covered by insurance.

Sonawane said parental misconceptions about the vaccine’s safety are commonplace, and doctors rarely have the time to debunk vaccine misinformation parents find online. “Positive information about vaccines doesn’t get posted on social media,” she observed.

Some parents fear that immunizing their children against HPV will encourage them to engage in sexual activity, although there is no evidence this happens. Aragones, among others, suggested that the best way for doctors to minimize parental opposition is to describe the vaccine’s anticancer role, limit discussing the link to sexual activity and include the immunization with the other vaccines that are routinely given to adolescents.

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