More data about the benefits of Merck’s original HPV vaccine Gardasil have arrived. Its protection can last over a decade, and it’s more powerful for those who get it earlier in their life, the longest follow-up study of the shot found.
Published in Pediatrics, the Merck-funded study was an extension from a base study that involved 1,661 boys and girls aged 9 to 15 in nine countries across four continents. Around 89% to 96% of participants remained seropositive against HPV types 6, 11 and 16 after 10 years, while immune responses against type 18 ranged from 77% to 79%, according to the study.
Preadolescents—those designated as those 12 or younger when they received the first dose—maintained 16% to 42% higher geometric mean titers compared with the adolescents in the study. None of the subjects developed HPV-related diseases, though 10 subjects had persistent infection lasting longer than six months, according to the researchers.
“These findings justify efforts to vaccinate subjects at the earliest opportunity,” wrote the team, led by Daron Ferris, M.D., of Augusta University’s Department of Obstetrics and Gynecology. “Moreover, by vaccinating preadolescents before exposure to HPV, the full potential of the vaccine is more likely to be realized.”
The CDC currently recommends HPV vaccination for children ages 11 to 12, but the vaccine can be given as early as age 9.
HPV types 6 and 11 account for about 90% of genital warts, while types 16 and 18 cause about 70% of cervical cancer cases and are identified as the reason behind many cases of vaginal and vulvar cancer, plus anal cancer and cancers of the head and neck.
The newer version of the vaccine, Merck’s Gardasil 9, offers additional protections against five other HPV types also responsible for those cancers; it has been shown to sustain antibody responses up to six years. Though the 10-year follow-up on Gardasil 9 won’t be available any time soon, Ferris’ team said data on the quadrivalent vaccine “should be translatable to” the 9-valent vaccine. Merck's Gardasil won FDA approval in 2006, followed by Gardasil 9 in 2014.
HPV vaccination rates in the U.S. are far from ideal, according to the CDC, as only 43% of teens completed the schedule. “If healthcare providers improve the rate of HPV vaccination, most aggressive types of cervical and genital neoplasia can be prevented,” the researchers wrote. About 17,500 women and 9,300 men are affected by HPV-related cancers each year.