Another important study published in Pediatrics last month adds to the growing body of clinical evidence showing that vaccinating the pediatric population against human papillomavirus (HPV) is both safe and effective in preventing some specific and not uncommon types of cancer. Katherine Bortz drills down into this now-1o-year-old study of quadrivalent HPV vaccine to look first at its immune response:
Of the 1,661 preadolescents and adolescents included in the study, seropositivity was observed in 89% to 96% 10 years after immunization.
Any time a new vaccine is developed, parents typically ask their pediatrician how long the vaccine is expected to last. (“Will a booster dose be needed?”) As predicted, this ongoing study demonstrates that antibodies to HPV persist (ie. the vaccine remains effective) 10 years after vaccination. It is unlikely that booster doses after the initial series will be necessary.
In both cohorts, the preteens and teenagers did not have any cases of HPV type 6, 11, 16 or 18, nor were any related diseases observed.
10 years after receiving HPV vaccine as part of the study, none of the preteens and teenagers developed genital warts or cancers related to the four HPV types contained in the vaccine. So the vaccine is doing what pediatricians say it will — prevent cancer caused by HPV.
Throughout the study period, no serious adverse events were reported.
But wait. Pediatricians don’t give their patients the quadrivalent HPV vaccine any longer. Instead, we now give girls and boys the 9-valent HPV vaccine (Gardasil-9) in order to prevent infections and cancer caused by five additional types of human papillomavirus. There are ongoing studies related to this version of the HPV vaccine but chances are the results will be similar in terms of immunogenicity, effectiveness, and safety.
The added benefit of giving the new 9-valent HPV vaccine instead of the old quadrivalent vaccine is that only two doses of Gardasil-9 are necessary to complete a series if the first dose is given before the 15th birthday. (Three doses are needed if vaccination commences after the 15th birthday.)
Pediatrician and vaccine expert, Dr. Paul Offit, recommends HPV vaccines in order to prevent cervical, vulvar, vaginal, penile, anal, and oral cancers, in addition to genital warts that no man or woman wants to get:
This study should further reassure doctors and their patients that the HPV vaccine—which as a 9-valent vaccine now has the capacity to prevent about 29,000 cases of cancer and 5,000 deaths from cancer every year — provides durable protection without any serious side effects. The only question that remains is why are some parents still hesitant to give this safe, cancer-preventing vaccine to their children.