Sexually transmitted infections after HPV vaccination of young women

HPV quadrivalent cancer preventing vaccine, known as Gardasil (or Silgard in Europe), can reduce the risk of several types of cancer by blocking sexually transmitted (along with a few other pathways) infection by human papillomavirus (HPV). There are more than 40 HPV sub-types that can infect the genital areas of males and females. Additionally, some HPV types can also infect the mouth and throat. HPV is generally transmitted from personal contact during vaginal, anal or oral sex. About one-quarter of those sub-types are implicated in a number of genital, anal and oral cancers.

In a broad review of all of the published clinical research involving HPV vaccines, there is a clear scientific and medical consensus that HPV vaccines are extraordinarily safe, they quickly reduce HPV infection rates in populations of adolescents and young adults, and by reducing HPV infection rate, we will eventually have a real and statistically significant reduction in the risks of many types of cancer.

And as I’ve said many times, there are just a handful of methods, supported by real scientific evidence, to reduce the risk of cancer–quit smoking, lose weight to be clinical “skinny”, stay out of the sun, remove radon gas from your house, and get the HPV vaccine. No, eating a non-GMO, organic blueberry-kale shake will absolutely have NO effect on your risk of getting cancer, unless you find that so disgusting that you lose substantial weight.



Despite the fact that Gardasil Stops Cancer, uptake of that vaccine has been fairly low in the USA. Part of the issue is that the internet is clogged with anecdotal (and ultimately unverifiable) beliefs that Gardasil is dangerous. A Canadian newspaper article, going all in with false balance and buying into post hoc fallacies, undoubtedly written by someone who is both a science denier and ignorant about causality in medicine, tries to scare off readers from Gardasil. If it was the only bogus article written by the so called “press”, I’d be outraged. I’m not any more, it’s just that there are so few real science writers out there.

Other anti-Gardasil types go dumpster diving in the VAERS database trying to show that Gardasil does this or does that.

But unlike the Canadian news article or VAERS junk data, peer reviewed real scientific articles, describing case-control studies that included controls, huge numbers (often into the millions of patients), unbiased design, and powerful statistical analysis that separates randomness from correlation or causality, have shown that HPV vaccines are incredibly safe, possibly the safest vaccines on the market.

Five of the largest studies, here, here, herehere, and here, which includes nearly 5 million injections have shown absolutely no deaths, serious adverse reactions, and, in some cases, adverse reactions occur in a lower rate than in the unvaccinated population (probably a statistical anomaly, but maybe vaccines have some risk reduction for some events).

One of the most enduring myths about Gardasil is that somehow it makes girls and boys more promiscuous, leading to more unprotected sex. Mostly, antivaccine myths lack plausibility, but there could be some logic that a teenager who now is protected against one sexually transmitted infection (STI) thinks they’re super men and women, and decided that they should turn suddenly into promiscuous vessels of STI’s. I guess this presumes that teenagers are illogical and stupid (I’m sure every parent of a teenager may have days when they’re convinced of this proposition)–however, it is a belief that has been thoroughly debunked by recent clinical studies, which has shown that these vaccinated kids do not suddenly become promiscuous.

In addition, in a national survey of pediatricians, about 60 percent believed that parents would be concerned that HPV vaccination would promote unsafe or promiscuous sexual behavior, and 11 percent of pediatricians themselves reported they were concerned about this. It is frustrating that even pediatricians buy into this myth.

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recent article published in JAMA Internal Medicine provides evidence that the HPV vaccine makes no difference in young women’s sexual behavior–they are just as like to engage in sex in the ways and frequency whether vaccinated with Gardasil or not.

According to Dr. Anupam Jena, assistant professor of health care policy at Harvard Medical School, lead author of the study:

The vast majority of studies do not find that public policies induce sexual activity. That being said, there are some high-quality studies that do find this behavioral response. For parents and policymakers and pediatricians to be concerned about the issue is not unfounded.

And Jena’s study does show that HPV vaccination does not induce a sudden increase in sexual activity and risky sexual behavior

The researchers used health insurance claims to determine whether STDs among females who were vaccinated with the HPV vaccine increased compared with those who were not. The researchers examined more than 200,000 medical records, checking for definitive reports of STIs, including AIDS, gonorrhea, herpes, syphilis and chlamydia. They measured the rate of STIs before vaccinations and after. They did not assess condom use or number of sexual partners (information that probably cannot be determined from most medical records).

These researchers also found that women who had the HPV vaccination had a higher rate of STIs both before and after they were vaccinated, which implied that women who choose to get a vaccine may already be sexually active–this data implies that these women consciously decided to get the vaccine because they were already sexually active. Furthermore, when the researchers compared vaccinated to unvaccinated females, they found the same rate of overall infection, leading them to conclude that the vaccine is not responsible for triggering sexual behavior. In other words, the HPV vaccination did not increase the incidence of STIs despite these young women being sexually active.

The CDC recommends that both boys and girls receive the first of the three part vaccine at age 11 or 12, to allow the immune system to build it’s response to the virus before teens become sexually active. The CDC now recommends the HPV vaccine for males through age 21 who did not get any or all doses when they were younger. The vaccine is also recommended through age 26 for men who have had sex with men, and for people with compromised immune systems, including HIV/AIDS patients, through age 26.

In an accompanying article in JAMA Internal Medicine, Dr. Robert A Bednarczyk, from the Rollins School of Public Health at Emory University, stated that:

These findings should not come as a surprise to researchers in the field of HPV vaccinology and should serve as continued reassurance that HPV vaccination does not lead to sexual disinhibition. However, this reassurance leaves us with the question, “How can we use these findings to address concerns of anxious parents of adolescents?”

Dr. Bednarczyk says that it’s more than just parents that need to be educated about the HPV vaccine, but also pediatricians (and other physicians who vaccinated children). They need to know that starting the vaccination series at 11 or 12 years old induces a more robust immune response than if it is done in older teenagers or young adults. They need to know that the HPV vaccine prevents cancer. They need to communicate this information to parents as accurately and forcefully as they do for other vaccines like for pertussis, meningococcal, or other diseases prevalent in teenagers.

Dr. Bednarczyk concluded that:

To date, much research has been conducted to identify HPV vaccination barriers, but less research has been conducted to identify the preferred content and mode of delivery of information to mitigate these barriers. Addressing this knowledge gap through the development and delivery of information relative to all key partners (adolescents, their parents, and their health care professionals)will be critical in removing the stigma of HPV vaccine in our efforts to fully use this vaccine. The materials should also address other fears that parents might have, including the safety of the vaccine, especially because many parents worry about their children receiving multiple vaccines at thesametime. In the meantime,physicians should recommend the HPV vaccine as part of the adolescent vaccination platform, as is done for the Tdap andMCV4 vaccines, and highlight the reasons that support early vaccination: better immune response, importance of vaccinating before sexual activity, and consistent evidence that HPV vaccination does not lead to increased sexual activity.

Gardasil is safe. Gardasil prevents cancer. It does not cause promiscuity or unsafe sexual behavior. And we have evidence of all three.

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The Original Skeptical Raptor
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Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!