Over on BigThink David Berreby writes on a study released Dec 13th that investigated the usage of the HPV vaccine:

Study: HPV Vaccine Is Not A Gateway to Sex

A frequently cited objection to widespread use of the Gardasil vaccine against Human Papillomavirus is that it will give children the message that it’s normal, expected and inevitable that they will have sex with a partner or partner who has had sex with others before. That is, for some parents, is a message they don’t want to send. At heart, that position is a matter of values and not facts. Still, maybe some parents can take comfort in this study (pdf), out today in the American Journal of Preventive Medicine: It found that the vaccine isn’t interpreted as a sexual all-clear. Quite the opposite: Girls who were vaccinated, the authors found, were no different in their later sexual behavior than were those who were not.

There are some nuances, as usual in science and especially in data gathering. From the study:

[…]

A main goal of this NSFG analysis was to explore any association between sexual behaviors and receipt of HPV vaccine. Results do not indicate a difference in sexual experience by HPV vaccine status. While an association was found in another national survey, neither that survey nor NSFG had data on age at vaccination that would allow further exploration of the fındings. Therefore, neither survey could assess the temporal relationship between vaccine and sexual initiation. Such data will be available in future surveys. Ascertaining the timing of receipt of HPV vaccine in relation to initiation of sexual activity would allow researchers to determine what percentage of girls/women are getting vaccinated before onset of sexual activity. This is important considering the prophylactic nature of the vaccines and the rapid acquisition of HPV soon after sexual initiation.

So there is more work to be done in studying this issue, but those who insist that HPV vaccination increases a woman’s proclivity to sexual activity should take note that assertion will be very hard to prove. For example:

However, ascertaining timing of vaccination to sexual activity would not be suffıcient to address concerns that receipt of HPV vaccine might promote earlier sexual initiation and riskier sexual behaviors. If there was an association and vaccination preceded initiation of sexual activity, it still could not be concluded that the sexual activity was due to a perceived lack of risk. Other explanations include provider likelihood to recommend to older adolescents who are more likely to initiate sex or that vaccine is sought by girls/ women who were planning initiation of sexual activity. […]

I suspect that one of the biases of those who claim vaccinations lead to riskier behavior is that they are selecting (and relaying anecdotally) subjects that are a subset of all women, a subset that would be more likely to engage in sexual activity in the first place. Understanding such biases in data collection is one of the most important tasks of scientists.

The study found some other interesting results:

Among sexually active women, a signifıcant difference was found between vaccinated and unvaccinated women in reported consistency of condom use; sexually active young women who had received the vaccine were more likely to report always using a condom in the past 4 weeks than sexually active young women who had not received the vaccine. This fınding could be due to girls/women who are more concerned about safer sex also being more likely to receive the vaccine, or that receipt of HPV vaccine (possibly through education about HPV or other STDs at the time of vaccination) leads to safer sex.

This is an important distinction lost on the ardent victorians: HPV vaccine may be associated with safer sexual practices, not necessarily an increased probability of sexual activity among all women!

The authors conclude:

[…] The lack of association between receipt of HPV
vaccine and initiation or increased frequency of sexual
behaviors should assuage some concern for a causal link
between the two.

Well yes, it should assuage some concern, but the likes of those who are using the HPV vaccination as a scare tactic, as we’ve seen in the GOP nomination process, most likely don’t care about scientific studies like these in the first place.

Finally also worth noting, this study raised some light also on the relationship of health care insurance and HPV vaccination:

Receipt of HPV vaccine was higher among those with insurance in both age groups.