Vaccine
Volume 33, Issue 21, Pages 2395-2516 (15 May 2015)
http://www.sciencedirect.com/science/journal/0264410X/33

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Evaluation of anthrax vaccine safety in 18 to 20 year olds: A first step towards age de-escalation studies in adolescents
Original Research Article
Pages 2470-2476
James C. King Jr., M.D., Yonghong Gao Ph.D., Conrad P. Quinn Ph.D., Thomas M. Dreier Ph.D., Cabrini Vianney M.S., Eric M. Espeland Ph.D.
Abstract
Background/objectives
Anthrax vaccine adsorbed (AVA, BioThrax®) is recommended for post-exposure prophylaxis administration for the US population in response to large-scale Bacillus anthracis spore exposure. However, no information exists on AVA use in children and ethical barriers exist to performing pre-event pediatric AVA studies. A Presidential Ethics Commission proposed a potential pathway for such studies utilizing an age de-escalation process comparing safety and immunogenicity data from 18 to 20 year-olds to older adults and if acceptable proceeding to evaluations in younger adolescents. We conducted exploratory summary re-analyses of existing databases from 18 to 20 year-olds (n = 74) compared to adults aged 21 to 29 years (n = 243) who participated in four previous US government funded AVA studies.
Methods
Data extracted from studies included elicited local injection-site and systemic adverse events (AEs) following AVA doses given subcutaneously at 0, 2, and 4 weeks. Additionally, proportions of subjects with ≥4-fold antibody rises from baseline to post-second and post-third AVA doses (seroresponse) were obtained.
Results
Rates of any elicited local AEs were not significantly different between younger and older age groups for local events (79.2% vs. 83.8%, P = 0.120) or systemic events (45.4% vs. 50.5%, P = 0.188). Robust and similar proportions of seroresponses to vaccination were observed in both age groups.
Conclusions
AVA was safe and immunogenic in 18 to 20 year-olds compared to 21 to 29 year-olds. These results provide initial information to anthrax and pediatric specialists if AVA studies in adolescents are required.