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Clin Infect Dis. 2015 Nov 15;61 Suppl 5:S578-85. doi: 10.1093/cid/civ513.

Higher Tetanus Toxoid Immunity 2 Years After PsA-TT Introduction in Mali.

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Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis Fogarty International Center, National Institutes of Health, Bethesda, Maryland.
Vaccine Evaluation Unit, Public Health England, Manchester Royal Infirmary, United Kingdom.
Centre pour le Développement des Vaccins, Ministère de la Santé, Bamako, Mali.
Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom.
Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom Medical Research Council Unit, Fajara, The Gambia.
Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, United Kingdom.



In 2010, mass vaccination with a then-new meningococcal A polysaccharide-tetanus toxoid protein conjugate vaccine (PsA-TT, or MenAfriVac) was undertaken in 1- to 29-year-olds in Bamako, Mali. Whether vaccination with PsA-TT effectively boosts tetanus immunity in a population with heterogeneous baseline tetanus immunity is not known. We assessed the impact of PsA-TT on tetanus toxoid (TT) immunity by quantifying age- and sex-specific immunity prior to and 2 years after introduction.


Using a household-based, age-stratified design, we randomly selected participants for a prevaccination serological survey in 2010 and a postvaccination survey in 2012. TT immunoglobulin G (IgG) antibodies were quantified and geometric mean concentrations (GMCs) pre- and postvaccination among all age groups targeted for vaccination were compared. The probability of TT IgG levels ≥0.1 IU/mL (indicating short-term protection) and ≥1.0 IU/mL (indicating long-term protection) by age and sex was determined using logistic regression models.


Analysis of 793 prevaccination and 800 postvaccination sera indicated that while GMCs were low pre-PsA-TT, significantly higher GMCs in all age-sex strata were observed 2 years after PsA-TT introduction. The percentage with short-term immunity increased from 57.1% to 88.4% (31.3-point increase; 95% confidence interval [CI], 26.6-36.0;, P < .0001) and with long-term immunity increased from 20.0% to 58.5% (38.5-point increase; 95% CI, 33.7-43.3; P < .0001) pre- and postvaccination.


Significantly higher TT immunity was observed among vaccine-targeted age groups up to 2 years after Mali's PsA-TT mass vaccination campaign. Our results, combined with evidence from clinical trials, strongly suggest that conjugate vaccines containing TT such as PsA-TT should be considered bivalent vaccines because of their ability to boost tetanus immunity.


Africa; conjugate; meningococcal vaccines; seroprevalence; tetanus

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