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. 2015 Nov 15;61 Suppl 5(Suppl 5):S578-85.
doi: 10.1093/cid/civ513.

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

Nicole E Basta  1 , Ray Borrow  2 , Abdoulaye Berthe  3 , Uma Onwuchekwa  3 , Awa Traoré Eps Dembélé  3 , Rachael Almond  2 , Sarah Frankland  2 , Sima Patel  2 , Daniel Wood  2 , Maria Nascimento  4 , Olivier Manigart  5 , Caroline L Trotter  6 , Brian Greenwood  4 , Samba O Sow  3
Affiliations

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

Nicole E Basta et al. Clin Infect Dis. .

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.

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Figures

Figure 1.
Figure 1.
Box plot of tetanus toxoid immunoglobulin G (IU/mL) distribution before and after a meningococcal A polysaccharide–tetanus toxoid protein conjugate vaccine mass vaccination campaign. The age given is age at enrollment for 2010 survey and age as of 1 December 2010 for postvaccination survey.
Figure 2.
Figure 2.
Tetanus toxoid immunoglobulin G (IgG) levels (IU/mL) by sex and age group before and after a Meningococcal A Polysaccharide–Tetanus Toxoid Protein Conjugate Vaccine mass vaccination campaign.
Figure 3.
Figure 3.
Predicted probability of short-term tetanus immunity (≥0.1 IU/mL) (A) and long-term tetanus immunity (≥1.0 IU/mL) (B) based on the adjusted logistic regression model by age group and sex before and after a Meningococcal A Polysaccharide–Tetanus Toxoid Protein Conjugate Vaccine mass vaccination campaign.
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