Serological response to cholera revaccination in a semi-closed community in Calcutta.

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 </=320 and agglutination </=40) in their prevaccination samples. Revaccination, therefore, appears to be useful as a booster for individuals having low titres.