Immunogenicity of partial doses of live oral cholera vaccine CVD 103-HgR in children in the United States.

In a phase 4, placebo-controlled, double-blind, multi-center study performed to assess the immunogenicity of a single oral dose of live, attenuated cholera vaccine, volunteers aged 2-17 years were randomized 6:1 to receive 1 × 109 colony forming units of PXVX0200 or placebo. In the subset of subjects who consumed < 80 % of the vaccine dose, seroconversion rates were calculated and stratified by amount consumed. Of 468 subjects dosed, a subset of 33 (7 %) received < 80 % of the vaccine dose. SVA seroconversion occurred in 75.8 % of these subjects, including 100 % (7/7) of those who took 50-80 % and 69.2 % (18/26) of those who took < 50 %, versus 98.5 % of those who consumed 80 % or more. Vaccination with PXVX0200 produced an immune response in most children who received partial dosing. Since SVA seroconversion is a strong correlate of protection, PXVX0200 may protect against cholera infection in children who ingest only part of the vaccine dose.