Safety And Efficacy Of Using Oral RBS/WC Cholera Vaccine In Population

Cholera is an acute, intestinal infectious disease caused by infection of the intestine with the sero-group 01 or sero-group 0139 of Vibrio cholerae, which is the major public health problem in the developing countries and undeveloped countries. The studies on cholera Vaccines have been carried through by the scientist all over the world for more than one century, and so many kinds of vaccines as killed whole cell vaccine, anti-cholera toxin Vaccine, combined vaccine of anti-bacterial and anti-toxin, and attenuated live vaccine have been developed successfully. Although it was proved in field trials that non-intestinal immunization can produce high level of seral antibodies, the titer of antibodies was not high in local intestinal mucous membrane. However, oral rBS/WC cholera vaccine (Shanghai Lianhe Sai'er Bioengineering Co., Ltd) can prevent from diarrhea caused by Vibrio cholerae, and infection with enterotoxigenic Escherichia coli. This study was to observe and assess the adverse reaction and immunological efficacy of oral rBS/WC cholera vaccine and provide the scientific basis for its' popularizing application. Materials and methods 3006 subjects of 13 villages were selected from 6 towns of zhangzhen, shangpu, lihai, songxia, gaibei and xietang in shangyu of Zhejiang province, which were divided into three groups according to the principles of random, double blind and control. Oral capsule labeled A, B and C was administered in each group, respectively. One piece was administered for each subject on the 1st, 8th and 28th day and another piece was administered for strengthen immunization after a year. The adverse reactions were observed for all subjects, and anti-CT antibody and vibriocidal antibody were assayed in 60 subjects selected from each group randomly at pre-administration and 1st, 3rd, 6th,and 12th post-administration. The diarrhea symptom was also surveilled in all subjects and their stool was detected for vibrio cholerae and enterotoxigenic Escherichia coli. Results There was no severe adverse reaction after administration except transient bellyache, diarrhea and headache etc, with the rate of 3.39% for the first adverse reaction. The rate of adverse reaction was higher in control group than that of experimental group, which probably be the psychogenic reaction. The rates of adverse reaction in the next two administrations were on the decrease gradually and there was no significant difference in two groups. The titer and the positive rate of antibody were the highest at one month after the whole course administration of oral rBS/WC cholera vaccine and then decreased gradually. Both the titer and the positive rate of anti-CT antibody increased after the strengthen immunization. Thirty five of 2763 cases had diarrhea in three month after the whole course administration of oral rBS/WC cholera vaccine by surveillance, with the seasonal occurrence rate of 1.27%, and all of cases with diarrhea were not caused by vibrio cholerae and enterotoxigenic Escherichia coli. Conclusion The adverse reaction of oral rBS/WC cholera vaccine was low and the severe adverse reaction was not observed in this study. The subjects administered the whole course administration of oral rBS/WC cholera vaccine had higher anti-CT antibody. In view of its fine immunological efficacy, oral rBS/WC cholera vaccine could be popularized and applied in proper population.