The efficacy of various routes of administration of rubella vaccine RA27/3 was evaluated in a group of children. The vaccinees were randomly divided into three groups: subcutaneous, nose drop, and aerosol spray. Immunization was evaluated in terms of serum antibody rise and clinical side effects. Seroconversion was achieved in 100% of the children with no significant difference in the geometric mean titers of serum antibody in the various groups. Thus, respiratory tract immunization of small children with rubella vaccine RA27/3 is equally effective, compared to the subcutaneous route, in stimulating serum antibody. Side effects occurred in only 4% of the vaccinees in each group, the symptoms being mild and transient. We believe local immunization is less painful than subcutaneous injection and is an acceptable technique for mass administration of the vaccine in children.
Serological response to cholera revaccination has been studied in a semi-closed community consisting of individuals mostly in the 2-20-years age-group. The subjects had been inoculated against cholera every year at the beginning of the local epidemic season. Pre- and post-vaccination sera were obtained from 29 subjects inoculated with cholera vaccine (test group) and 28 from subjects inoculated with TAB vaccine (control group). These sera were tested for vibriocidal and agglutination titres. The geometrical means of the vibriocidal and agglutination titres of the post-vaccination sera in the test group rose by 490% and 463% respectively. This booster effect was observed mostly in individuals in the 2-14-years age-group, who had low titres (vibriocidal
An important consideration in evaluating vaccines is the duration of immunity. The only really important measure of this immunity is the protection against infections and/or illness at various time intervals, following natural or artificial challenge. There are few data of this sort, more commonly immunity is estimated by measuring serum antibody, in many instances an erroneous measure. Serum antibody levels to respiratory viruses fall only slightly 6 months following infection or immunization. It is difficult to assess the duration of antibody for much longer than this, because of problems with intercurrent infection. With respiratory bacterial infections, e.g. pneumococcal pneumonia, parenterally-induced immunity probably lasts for only several months. Secretory antibody induced by inactivated viral vaccines, seems to persist for about a year, after having reached a peak level at about 4-6 weeks following immunization. Work with the live attenuated polio virus vaccine indicates longer lasting immunity, with detectable antibody persisting for up to 34 months. Restimulation with the inactivated polio virus vaccine produced no evidence of a secondary response (memory). Following booster immunization with influenza very little evidence of memory is seen. Cell-mediated immunity (CMI): in guinea pigs BCG sensitization can be demonstrated for at least 2-9 months. In humans, intracutaneous BCG immunization leads to positive tuberculin reaction in 6-10 weeks, and skin sensitivity lasts an average of about 4 years. There is contradicting data as to the duration of protection against infection following BCG immunization. Local and systemic CMI have been shown to exist independently of each other in experimental animals and man.
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