IMMUNOGENICITY & SAFETY OF VAQTAÔ IN JIANGSU, CHINA
Chen X,
Chen Z, Lu W, Wang H, Chen L*, Poerschke G*, Eves K*, Kuter B*;
Zhang Jia Gang Anti-epidemic Station; Zhang Jia Gang Feng Huang Hospital;
Jiangsu Center of Disease Control; China; MSD China*; Merck
& Co., Inc., PA, USA*
Objective: To
determine the immunogenicity, safety and tolerability of VAQTAÔ [Hepatitis A [HA] vaccine, purified
inactivated, MSD] in healthy Chinese children in an area of high to
intermediate endemicity of HA. Methods:
Eligible subjects ages 2 to 17 years received 25U/0.5 mL of VAQTAÔ, IM, at 0 and 24 weeks schedule. Serum
samples were obtained prior to dose 1 and 4 weeks after the 1st
and 2nd dose, respectively. To evaluate immunogenicity
after vaccination with VAQTAÔ, a modified Abbott HAVABÒ
kit was used. Samples with anti-HAV titers ³ 10 mIU/mL were
considered seropositive. Adverse
Events [AE¡¯s] were monitored for 14 days after each vaccination visit.
Results: 50
subjects [24 male, 26 female] were enrolled. Mean age was 6.1 ¡À 0.8 years. Mean body weight was 20.4 ¡À 2.8 kg. Mean height was 116.6 ¡À 5.5 cm. 12 (24%) were found to be
seropositive prior to dose 1 and were excluded from analysis. Serological
results were available for 38 baseline seronegative subjects post-dose 1
and 37 post-dose 2. After primary dose 34/38 (89.5%, 95% CI 75 to 97)
seroconverted. GMT was 33.1 mIU/mL (95% CI 22.4 to 49.0). After the booster
dose all subjects (37/37)
seroconverted, giving a seroconversion of 100%. GMT was 7585.8 mIU/mL (95%
CI 5623.4 to 10471.3). AE¡¯s to VAQTAÔ were generally mild and transient.
Conclusions: A pediatric two dose regimen of VAQTAÔ
was found to be highly immunogenic and generally well tolerated in healthy
Chinese children. These data support the use of HA
vaccine at an early age.