Abstract
The impact of alternate routes of vaccine administration, subcutaneous (SC) or intramuscular (IM), on the safety and immunogenicity of herpes zoster subunit candidate vaccine (HZ/su) was assessed in Japanese adults aged ≥ 50 y. During this phase III open-label study, 60 subjects were randomized (1:1) to receive HZ/su through SC or IM routes in a 0, 2 month schedule. Vaccine response rates (VRRs) and geometric mean concentrations (GMCs) of varicella zoster virus glycoprotein E (gE)-specific antibodies were determined by ELISA. Solicited and unsolicited symptoms were recorded for 7 and 30 d after each vaccination and graded 1-3 in severity. Serious adverse events (SAEs) were recorded throughout the study. At one month post-dose 2, VRRs were 100% (95% Confidence Interval (CI): 88.1-100) in both groups; anti-gE antibody GMCs were 44126.1 mIU/ml (95% CI: 36326.1-53601.0) and 45521.5 mIU/ml (95% CI; 37549.5-55185.9) in the SC and IM groups, respectively. Injection site reactions (pain, swelling and redness) were common, and observed more frequently following SC administration. Grade 3 redness and swelling were more frequently observed after SC administration. Fatigue and headache were the most frequently reported general symptoms for both routes of administration. Ten and 7 unsolicited AEs were reported in the SC and IM group, respectively. Two unsolicited AEs (1 in SC; 1 in IM) were considered related to vaccination by the investigator. Three non-fatal SAEs considered unrelated to vaccination were reported during the study. Administration of the HZ/su vaccine candidate resulted in a substantial immune response that was comparable between SC and IM subjects, but local reactogenicity may be greater for SC.