A cluster randomized non-inferiority field trial on the immunogenicity and safety of tetanus toxoid vaccine kept in controlled temperature chain compared to cold chain.

BACKGROUND: In resource-poor settings, cold chain requirements present barriers for vaccine delivery. We evaluated the immunogenicity and safety of tetanus toxoid (TT) vaccine in "Controlled Temperature Chain" (CTC; up to 40 °C for

METHODS: A cluster randomized, non-inferiority trial was conducted in Moïssala district, Chad, December 2012-March 2013. Thirty-four included clusters were randomized to CTC or SCC. Women aged 14-49 years, eligible for TT vaccination and with a history of ≤1 TT dose, received two TT doses 4 weeks apart. Participants were blinded to allocation strategy. Tetanus antibody titers were measured using standard ELISA at inclusion and 4 weeks post-TT2. Primary outcome measures were post-vaccination seroconversion and fold-increase in geometric mean concentrations (GMC). Non-inferiority was by seroconversion difference (TTSCC-TTCTC)

RESULTS: A total of 2128 women (CTC=1068; SCC=1060) were recruited. Primary intention to vaccinate analysis included 1830 participants; 272 of these were included in the seroconversion analysis. Seroconversion was reached by >95% of participants; upper 95%CI of the difference was 5.6%. Increases in GMC were over 4-fold; upper 95%CI of GMC ratio was 1.36 in the adjusted analysis. Few adverse events were recorded.

CONCLUSIONS: This study demonstrates the immunogenicity and safety of TT in CTC at

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