{"id":146,"date":"2024-05-08T17:13:16","date_gmt":"2024-05-08T17:13:16","guid":{"rendered":"https:\/\/www.merckvaccines.com\/vaqta\/?page_id=146"},"modified":"2026-03-26T09:23:06","modified_gmt":"2026-03-26T09:23:06","slug":"pediatric-efficacy-immunogenicity","status":"publish","type":"page","link":"https:\/\/www.merckvaccines.com\/vaqta\/pediatric-efficacy-immunogenicity\/","title":{"rendered":"Efficacy and Immunogenicity \u2013\u2028Pediatric"},"content":{"rendered":"\n\n
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VAQTA\u00ae (Hepatitis A Vaccine, Inactivated) \u2028pediatric clinical data \u2013 efficacy \u2028and immunogenicity<\/strong><\/h1>

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VAQTA has been FDA-approved for over 25 years.<\/strong><\/h2><\/div>\n\n\n\n
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VAQTA demonstrated 100% efficacy against hepatitis A in the landmark Monroe study of 2 to 16-year-oldsa<\/sup><\/strong><\/p>\n\n\n\n

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In the Monroe study, VAQTA demonstrated 100% efficacy against hepatitis A with 21 cases occurring in the placebo group and none in the vaccine group (P < 0.001) \u226550 days after vaccination.<\/span><\/p>\n\n\n\n

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Following review of the interim analysis of the initial study after a single dose, the monitoring committee recommended that the study be terminated so that the placebo recipients could be vaccinated. A booster dose was administered to a subset of vaccinees 6, 12, or 18 months after the primary dose.<\/p>\n\n\n\n

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Clinical study design<\/strong><\/h3><\/div>\n\n\n\n
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a<\/sup>An initial randomized, double-blind, placebo-controlled study was conducted to evaluate the efficacy of a single dose of VAQTA in a community with recurrent outbreaks. In this study, 1037 children, 2 to 16 years of age, were enrolled. Each child received an intramuscular dose of VAQTA (25 U) (n=519) or placebo (n=518). Efficacy was based on clinically confirmed cases of hepatitis A occurring \u226550 days after vaccination.<\/p>\n\n\n\n

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After 5 months, the initial study was terminated so that the vaccine could be provided to the subjects in the placebo group. A second (booster) dose was administered at 6, 12, or 18 months after the first dose of VAQTA. All vaccines were closely monitored for clinically confirmed cases of hepatitis A from 1991 to January 2001.<\/p>\n\n\n\n

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The total duration of the protective effect of VAQTA in healthy vaccinees is unknown at present.<\/p><\/div><\/div><\/p>\n\n\n\n

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Vaccination with VAQTA may not result in a protective response in all susceptible vaccinees.<\/p><\/div><\/div><\/p>\n\n\n\n

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VAQTA demonstrated 100% efficacy*<\/sup>across multiple studies<\/strong> after the second dose.<\/strong><\/h2><\/div>\n\n\n\n
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Clinical study design<\/strong><\/h3><\/div>\n\n\n\n
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The efficacy of VAQTA was evaluated in a clinical trial that included children 12 through 23 months of age who were randomized to receive the first dose of VAQTA with or without\u202fM-M-R\u00aeII<\/sub>\u202f(Measles, Mumps, and Rubella Virus Vaccine Live) and VARIVAX\u00ae (Varicella Virus Vaccine Live) and the second dose of VAQTA with or without\u202fTripedia<\/em>\u202f(diphtheria and tetanus toxoids and acellular pertussis vaccine) and optionally either oral poliovirus vaccine (no longer licensed in the US) or\u202fIPOL<\/em>\u202f(Poliovirus Vaccine Inactivated).<\/p>\n\n\n\n

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Immunogenicity data were combined from 11 randomized clinical studies in children and adolescents 2 through 18 years of age who received VAQTA (25 U\/0.5 mL). These included administration of VAQTA in varying doses and regimens (N=404 received 25 U\/0.5 mL), the Monroe Efficacy Study (N=973), and comparison studies for process and formulation changes (N=1238).<\/p>\n\n\n\n

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*The efficacy of VAQTA in 1 through 18 year-olds was based upon immunogenicity measured 4 to 6 weeks following vaccination.<\/p>\n\n\n\n\n

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