The Human Papilloma Virus vaccine or HPV was first introduced in 2006. It was first approved by the country of Gabon in Africa (Yes, I had to Google Map it) in March 2006 but then soon after by Mexico, Australia and the US in June 2006. Since then it has been approved in 129 countries and as of the end of 2015 205 million doses have been administered. The original HPV4 (against strains 6, 11, 16 & 18) has since been replaced by the HPV9 (adding strains 31, 33, 45, 52 & 58) introduced in 2014. (There is also a bivalent HPV vaccine which just covers 16 &18)
Worldwide, HPV is the most common STD and cervical cancer is the 4th leading cause of cancer in women. (> 500,000 new cases in 2012) HPV is the cause of all cervical cancers as well as the majority of anal, vaginal, and penile cancers and many of the vulvar and oropharyngeal cancers with strains 16 & 18 being the cause of the vast majority of the cancers while 6 &11 cause almost all of the anogenital warts.
The schedule most US physicians are familiar with is 0, 2, and 6 months, however the WHO in 2014 has approved an alternate 0, 6-12 month 2-shot regimen for 9-14 year olds after finding it “noninferior” to the 3-shot regimen. (In fact the ACIP is also considering the 2 shot schedule.)
A recent review, coinciding with the 10th anniversary of the vaccine, was done to “quantify the reported effectiveness and impact of 4vHPV vaccination on HPV infection, anogenital warts, and cervical cytological and histological abnormalities.” Cancer rates were not evaluated given the long period of time they take to develop.
Even still, the results were impressive. 58 studies were reviewed which covered data from 9 different countries. In most studies declining HPV infection rates were detected as early as 4 years after vaccine introduction. After 6 years in Australia, women who completed the entire series had an 86% reduction while those that received only 1 or 2 immunizations still had a 76% reduction. Data from the US showed a similar reduction (89%) in sexually-active females 14-24 years, 1 or 2 shot group. While these reductions were comparisons to unvaccinated peers, reductions from prevaccination cohorts were shown as well and even the unvaccinated females in the postvaccine era showed decreased rates (17-49%) reflecting likely herd immunity. As expected, rates of genital warts and cervical cytology abnormalities also showed declines in all the studies and countries represented.
Implementation has varied across the globe where many countries giving the vaccine in schools, other in health centers and some in both. Rates have also varied from the US with 3-shot completion of 40% female & 22% males, France 17% of 16 year olds, to > 80% in the UK, Denmark, Iceland, Colombia, Bhutan, Malaysia, Rwanda, and South Africa among others.
The expectation with such dramatic declines in HPV infection will be a (hopefully as) dramatic decline in cervical cancer rates over the next 10-20 years. Perhaps by then pap smears will be a thing of the past?
Jeff Ribordy, MD, Regional Medical Director