Immunogenicity And Safety Of An E.coli-produced Hepatitis E Vaccine In The Elderly Over The Age Of 65

Objectives:.To evaluate the immunogenicity and safety of an E.coli-produced Hepatitis E vaccine in the elderly over the age of 65.Methods:This study is an open label design.Elderly participants over 65 were enrolled in vaccine group and participants aged from 18 to 65 were enrolled in immunogenicity control group.Three doses of Hecolin(?)were given to the two groups at 0,1 and 6 months.Adverse events occurring within 30 days after each dose and serious adverse events during the entire trial were collected for the safety analysis of vaccination.Serum samples before immunization and 1 month after the third dose were obtained from participants of the two groups for assessment of immunogenicity.Moreover elderly participants over 65 were enrolled in safety control group without vaccination to collect the adverse events.Results:200 elderly participants over 65,201 participants aged from 18 to 65 and 200 elderly participants over 65 were assigned vaccine group,immunogenicity control group and safety control group respectively after informed consent and screening.In baseline seropositive subset,seroconversion rates of IgG against hepatitis E virus(HEV)of vaccine group and immunogenicity control group were 97.09%(95%CI:91.72-99.40)and 96.97%(95%CI:89.48-99.63)respectively when three doses were given,and they were 96.20%(95%CI:89.30-99.21)and 100.00%(95%CI:96.87-100.00)respectively in the baseline seronegative subset.The above difference between the two groups were not statistically significant(P>0.05).In baseline seropositive subset,geometric mean concentration(GMC)of the two groups 1 month after the third dose were 19.65(95%CI:16.80-22.98)and 24.52(95%CI:21.63-27.81)respectively when three doses were given,and they were 5.36(95%CI:3.88-7.41)and 10.84(95%CI:9.42-12.47)respectively in the baseline seronegative subset.The above difference were statistically significant(P<0.05),which means the GMC in elderly people are affected by age and IgG status of pre-vaccination mostly.However,100%of baseline seropositive people and 93.67%of baseline seronegative people in vaccine group have GMC level not less than 1 Wu/mL.The incidence of adverse events in the vaccine group,immunogenicity control group and safety control group were 40.00%,42.29%and 40.00%respectively,the difference between the vaccine group and immunogenicity control group or the vaccine group and safety control group were not statistically significant(P>0.05).Most adverse events were moderate.Pain,itching and swelling at injection sites,as well as fever were the most common adverse events after vaccination in the vaccine group and immunogenicity control group.No serious adverse events were related to vaccination.Conclusions:The results showed that Hecolin.is safe and immunogenic for elderly over the age of 65 and suggest that it could prevent new HEV infection.