A decade after its introduction, the vaccine for human papillomavirus has reduced the prevalence of this cancer-causing STD in teenage girls by nearly two-thirds. It’s an incredible success story, leading experts to question why HPV vaccinations aren’t more common in the United States.
According to a new study in Pediatrics, there was a 64 per cent decrease in HPV prevalence among teenage girls aged 14 to 19, and a 34 per cent decrease among women aged 20 to 24, within six years of the vaccine’s introduction. The US federal research team, headed by Elizabeth R. Unger from the Centers for Disease Control and Prevention (CDC), investigated the prevalence of the disease in women and girls of various age groups before the vaccine was introduced in 2006, and compared the prevalence in the same age groups between 2009 to 2012. Only girls were studied because the recommendation to vaccine boys wasn’t issued until 2011 (the researchers say they will include boys in future studies).
“The vaccine is more effective than we thought,” Debbie Saslow of the American Cancer Society told the New York Times. And vaccinated teenagers are not spreading the virus, so “they also protect the people who haven’t been vaccinated”.
HPV is the most common sexually transmitted infection in the United States. The CDC says nearly all sexually active men and women will contract some form of it at some point in their lives. Most people will clear the virus, but some forms of HPV persist, leading to genital warts and certain forms of cancer, including cervical, anal, penile, mouth and throat cancers.
When the vaccine was introduced 10 years ago, the CDC immediately recommended it be administered to all adolescents. But today, only 40 per cent of girls and 20 per cent of boys in the US are immunised. Part of the problem has to do with the unfounded claim that HPV vaccines will somehow make girls more promiscuous; a 2014 Canadian study quickly dispelled this false association.
But there are other barriers as well. As the New York Times reports:
In other countries, the vaccine is often given in two doses, particularly to girls younger than 15. In the United States, it is given in three doses. An immunization advisory committee to the C.D.C. will convene this week to learn more about the efficacy of the lower dose.
And in some countries, the vaccine is either mandatory or at least offered at school, its cost covered by a national health care system, making administration more streamlined and comprehensive. Such measures helped Rwanda achieve a 93 per cent immunization rate in girls. Australia, where the vaccine is offered free to schoolgirls, accomplished a 92 per cent reduction in genital warts in women under 21, a study showed.
But in the United States, the vaccine is largely optional.
As paediatric specialist Joseph A. Bocchini Jr. pointed out, one way to deal with the problem is to exclude the sexually transmitted nature of the virus from the conversation. “We don’t really discuss how people become infected with every vaccine-preventable disease,” he said.
Perhaps instead of framing it as something related to sex, healthcare providers should call it for what it really is: The world’s first cancer vaccine.
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