In December, the FDA expanded the age indication for Merck’s recently approved Gardasil 9 HPV vaccine to include males aged 16 to 26 years, matching the indication of this vaccine for females. The 9-valent vaccine has demonstrated comparable antibody responses to the four HPV types included in the quadrivalent formulation and effectively prevented infection and disease related to five additional HPV types.
By the end of 2016, Merck expects that the remainder of health care providers in the U.S. will have fully transitioned to using 9vHPV, according to Liana R. Clark, MD, medical director of Merck Vaccines. In addition, Merck will continue to manufacture 4vHPV (Gardasil) vaccine as it is licensed in 129 countries worldwide.
With both vaccines equally indicated, physicians are now questioning when to use their remaining supply of 4vHPV vaccine.
“I think the problem is what to do with the health departments and the physicians’ offices that have the 4vHPV vaccine on hand,” Jose R. Romero, MD, professor of pediatrics at the University of Arkansas for Medical Sciences, told Infectious Disease News. “Right now, the Advisory Committee on Immunization Practices has not made a recommendation to begin vaccination with 4vHPV and then switch to 9vHPV. They’re just saying, ‘Use what you have and use it up.’ ”
Prioritizing HPV in males
Since protection offered by the five additional strains in 9vHPV rises only 4% in males vs. 14% in females, one strategy of using up remaining 4vHPV vaccine is to administer it only to males, according to Sandra Adamson Fryhofer, MD, an internal medicine physician in private practice and an adjunct associate professor of medicine at Emory University.
However, by giving the 4vHPV to males with 9vHPV available, clinicians would be administering a vaccine that protects against fewer cancer-causing HPV strains. Thus, in a better world, 9vHPV, and not 4vHPV, would be the only choice for clinicians, she said.
“We cannot predict who might be in that 4%,” Fryhofer told Infectious Disease News. “Ideally, it would be nice if the company would just switch out for clinicians, at no charge, 9vHPV for remaining 4vHPV. But at this point, that is not what they are doing.”
Another strategy is to offer both vaccines as part of the three-dose regimen, according to Romero.
“Some physicians are starting vaccination with 4vHPV, giving a dose, and then switching to 9vHPV for the last two,” he said. “I think I would probably use 4vHPV initially and then switch to 9vHPV. But, that’s just a personal practice.”
While remaining 4vHPV vaccine should be used in males, any HPV vaccine in general needs to be administered to males at a higher rate, according to Clark, who noted a recent study in Pediatrics, which showed that providers are not recommending the 4vHPV or 9vHPV vaccine at the same rate to adolescent males as they are to adolescent females. According to Clark, providers can increase vaccination coverage by improving their recommendation rate for females as well as males.
Vaccinating still first priority
The CDC estimates that an additional 53,000 cases of cervical cancer could be prevented in girls aged 12 years and older by increasing three-dose HPV vaccination coverage (from about 40% in 2014) to 80%. In addition, for every year that vaccination rates do not improve, another 4,400 women will develop cervical cancer. Thus, a more pressing issue than what to do with excess 4vHPV vaccine is to ensure that everyone is vaccinated, according to Fryhofer.
“The bottom line is vaccinating with any of the available vaccines will protect against HPV strains that cause about 64% of all HPV-related cancers,” she said. “Vaccinating with any available product is much better than not vaccinating at all.” – by Will Offit
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Disclosures: Clark is medical director of Merck Vaccines. Fryhofer is an American College of Physicians liaison to the ACIP. Infectious Disease News was unable to confirm Romero’s relevant financial disclosures at the time of publication.