The results of a study conducted by Epicentre /Médecins Sans Frontières (MSF) assessing the immunogenicity and safety of a tetanus toxoid vaccine have been recently published in Vaccine
The study was conducted in collaboration with the Project Optimize, the Belgian Institute of Public Health (WIV-ISP) and the Ministry of Health of Chad. A cluster randomized, non-inferiority trial was conducted in Moïssala district, Chad, between December 2012 and March 2013. Prior to the study, stability indicator parameters of TT kept in CTC were shown to meet international requirements after exposure of vaccines in the study area to temperatures between 24.6 and 40.1°C (mean 31.2C°) for 30 days. Women aged 14-49 years, eligible for TT vaccination and with a history of ≤1 TT dose were allocated to CTC or standard cold chain (SCC). Participants received two TT doses 4 weeks apart. 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).
A total of 2,128 women (CTC=1,068; SCC=1,060) participated in the study. Seroconversion was reached by >95% of participants in the CTC and cold chain groups; 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.
This study demonstrates that TT can be used in CTC without a significant loss of vaccine effectiveness. The use of TT in CTC could facilitate the implementation of Supplementary Immunization Activities (SIAs) targeting high-risk populations living in remote and hard to reach areas.
[sup] 1[/sup] In press: Juan-Giner A, et al. A cluster randomized non-inferiority trial on the immunogenicity and safety of tetanus toxoid vaccine kept in controlled temperature chain compared to cold chain. Vaccine (2014), http://dx.doi.org/10.1016/j.vaccine.2014.09.027