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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.

Author information

1
Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis Fogarty International Center, National Institutes of Health, Bethesda, Maryland.
2
Vaccine Evaluation Unit, Public Health England, Manchester Royal Infirmary, United Kingdom.
3
Centre pour le Développement des Vaccins, Ministère de la Santé, Bamako, Mali.
4
Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom.
5
Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom Medical Research Council Unit, Fajara, The Gambia.
6
Disease Dynamics Unit, Department of Veterinary Medicine, University of Cambridge, United Kingdom.

Abstract

BACKGROUND:

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.

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

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.

KEYWORDS:

Africa; conjugate; meningococcal vaccines; seroprevalence; tetanus

PMID:
26553691
PMCID:
PMC4639490
DOI:
10.1093/cid/civ513
[Indexed for MEDLINE]
Free PMC Article

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