Formalin inactivated Hantaan virus vaccine (Hantavaxr) purified from suckling rate brains is currently licensed in Korea. This vaccine was demonstrated 97% of seroconversion rate and no significant side reaction in adult volunteers with standard
dose of
0.5ml (10,249 ELISA unit/ml). There is no data in children. We have recently compared results of the safety and immunogenicity of Hantaan virus vaccine in healthy children to investigate the seroconversion rate with half of recommended adult dose
in
standard vaccination schedule. Sixty five children with age between eight to eighteen were randomly assigned to two groups. Full dose group (FDG) (n=29, mean age 14 yrs) recieved 0.5ml (4,096 ELISA unit) of Hantavax and half dose group (HDG)
(n=36,
mean
age 10 yrs) received 0.25ml (2,049 ELISA unit). Both group was treated with two consecutive subcutaneous injections, according to 0 and 4 weeks vaccination schedule. Immunogenicity was assessed by determination of IgG antibody titers for vaccine
antigens using immunofluorescent antibody technique in four different time period, prior to vaccination (T0), 4 weeks after first dose(T1) and 4 weeks after second dose (T2), 16 weeks after second dose (T5). Reactogenicity was assessed by nurse
recording of local and general reactions for one week after administration of each dose. The seroconversion rate and geometric mean titers (GMTs) between two groups were as follows; seroconversion rate of HDG was 97.1% and that of FDG was 96.3%
at
T2.
The GMTs of HDG was 206 and that of FDG was 217 at T2. there was no significant general reaction during follow up, except mild fever (1), induration and redness (2) at the injection site. We concluded that low dose administration of Hantaan virus
vaccine, 0.25ml, subcutaneously may be optimum in immunogenicity for the immunization of children, and we are waiting the results of other studies in progress of this vaccine in children.
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