Salmonella paratyphi A conjugate vaccine(Lanzhou Institute of Biological Products)

To observe the antibody levels of the study population after different doses and different immunization schedules of Paratyphoid A conjugate vaccine, and to evaluate the appropriate immunization dose and immunization schedule of Paratyphoid A conjugate vaccine. To evaluate the safety of different doses of Paratyphoid A conjugate vaccine in the study population. To evaluate the immunogenicity and safety of Paratyphoid A conjugate vaccine in different age groups.