Children and adolescents receiving the 9-valent human papillomavirus vaccine Gardasil 9 along with the Menactra meningococcal vaccine and a Tdap booster at the same visit do not experience decreased effectiveness or safety from any of the vaccines, a study showed.
The titers from all three vaccines were noninferior when administered together, compared with administration of the Tdap (tetanus, diphtheria, and acellular pertussis) and the meningococcal vaccine a month after the first HPV-9 dose. Adverse events also were similar across both groups, except injection-site reactions were more common in those receiving all three vaccines together initially.
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“Providing vaccinations to adolescents is challenging because they make infrequent health care visits,” wrote Dr. Andrea Schilling of Alemana-Universidad del Desarrollo in Santiago, Chile, and her associates. “Concomitant administration would minimize the number of visits required to deliver each vaccine individually and therefore facilitate adherence to recommended vaccination regimens.”
Boys and girls aged 11-15 who self-reported as sexually naive in Chile, Colombia, Mexico, Peru, and the United States received recommended vaccines between October 2009 and February 2011. Among the 1,241 participants who received the 9-valent HPV vaccine, 621 of them received the Menactra meningococcal vaccine, covering Neisseria meningitidis serotypes A, C, Y, and W-135 (MCV4), and Tdap vaccines at the same visit. The other 620 participants received the MCV4 and Tdap vaccines 1 month after the HPV vaccine dose (Pediatrics. doi: 10.1542/peds.2014-4199).
Both groups showed similar levels of geometric mean titers for all nine HPV types included in Gardasil 9, all four N. meningitidis serotypes included in MCV4, and diphtheria, tetanus, and pertussis 4 weeks after the third dose of Gardasil 9. Both groups had 100% seroconversion for all HPV types at 7 months after the first dose. In addition, at least 75% of participants in both groups showed at least a fourfold increase in titers to N. meningitidis serogroup A, and at least 89% in both groups showed a fourfold increase for serogroups C, Y, and W-135. Finally, at least 99.8% of participants across both groups had at least 0.1 IU/mL diphtheria and tetanus titers 4 weeks after the Tdap booster. Antibodies to pertussis proteins were likewise noninferior in the concomitant group, compared with the nonconcomitant group.
The most commonly reported adverse events were pain, redness, or swelling at the injection site, reported by 85.3% of those receiving all three vaccines in the same visit and by 85.1% of those receiving the Tdap and MCV4 after the 9-valent HPV vaccine. However, 14.4% of those who received all the vaccines together reported swelling at the injection site, compared with 9.4% of those who received the MCV4 and Tdap a month after the HPV-9. The authors said that the higher rate for combined administration was attributable to the concomitant administration of the Tdap with the HPV vaccine. Otherwise, 0.8% of participants in both groups reported serious adverse events, all deemed unrelated to the vaccine.
“In the United States, coverage for the first dose of HPV vaccine remains substantially lower (by 20-25 percentage points) than coverage for other vaccines recommended by the Advisory Committee on Immunization Practices for children 11-12 years of age,” the authors wrote. “It is estimated that coadministration of HPV vaccine with other vaccines, such as diphtheria, tetanus, pertussis, meningococcal conjugate, and influenza vaccines, could increase coverage for the first dose of HPV vaccine to more than 90%.”
The investigators said the main limitation of the study was that it was not blinded. “As such, safety assessment could have been biased toward an overestimation of [adverse events],” they wrote.
The research was funded by Merck & Co. Dr. Schilling reported receiving past research support from Merck and honoraria from Merck-Chile, Grunenthal-Chile, and Grunenthal-L.A. Her associates reported financial relationships with numerous pharmaceutical companies.