A field study of inactivated vaccine against epidemic hemorrhagic fever

To assess the safety and antibodies response of the three lots and two immunization procedures of inactivated vaccine prepared with Meriones unguicu/atus kidney cells infected with Z10 strain of EHFV by Shanghai Institute of Biological Products, a population vaccination trial was conducted among the students and soldiers of a military college in Shaanxi Province from March to June, 1992. Of 1 186 people, 550 were randomly divided into five groups. Blood samples were collected from the subjects before and after vaccination. Three groups were inoculated with one of the three lots on 0, 7, 28 d, respectively. Another group was vaccinated with lot 91-32 on 0. 30, 60 d, the rest with placebo on 0, 7, 28 d. The vaccination rate was 93.5%. All of the vaccinees were observed for inoculation reaction. The reaction rate was 0.6%. H1 and IgM antibodies were measured by McAb-ELISA and Mac-ELISA, respectively. The average seroconversion rate was 49.5% (35.7% ~53.8%). Geometric mean tiler (GMT) of HI antibody of three lots were 1 :208, 1 :211. 1 : 156, respectively. There was no significant difference in seroconversion rate and GMT between three lots. The results suggest that the preparation technology of the vaccine is reliable. No significant difference was found between the two procedures. The seroconversion rates of the antibodies in placebo group were 0%. It showed that these vaccines were eflective.