TY - JOUR
T1 - Population-level persistence of immunity 2 years after the PsA-TT mass-vaccination campaign in Mali
AU - Basta, Nicole E.
AU - Borrow, Raymond
AU - Berthe, Abdoulaye
AU - Dembélé, Awa Traoré Eps
AU - Onwuchekwa, Uma
AU - Townsend, Kelly
AU - Boukary, Rahamatou M.
AU - Mabey, Lesley
AU - Findlow, Helen
AU - Bai, Xilian
AU - Sow, Samba O.
N1 - Publisher Copyright:
© 2015 The Author. Published by Oxford University Press on behalf of the Infectious Diseases Society of America.
PY - 2015/11/15
Y1 - 2015/11/15
N2 - Background. In 2010, Africa's first preventive meningococcal mass vaccination campaign was launched using a newly developed Neisseria meningitidis group A (NmA) polysaccharide-tetanus toxoid conjugate vaccine, PsA-TT (MenAfriVac), designed specifically for the meningitis belt. Given PsA-TT's recent introduction, the duration of protection against meningococcal group A is unknown. Methods. We conducted a household-based, age-stratified seroprevalence survey in Bamako, Mali, in 2012, 2 years after the vaccination campaign targeted all 1- to 29-year-olds. Randomly selected participants who had been eligible for PsA-TT provided a blood sample and responded to a questionnaire. Sera were analyzed to assess NmA-specific serum bactericidal antibody titers using rabbit complement (rSBA) and NmA-specific immunoglobulin G (IgG) by enzyme-linked immunosorbent assay. The proportion of participants putatively protected and the age group- and sex-specific rSBA geometric mean titers (GMTs) and IgG geometric mean concentrations (GMCs) were determined. Results. Two years postvaccination, nearly all of the 800 participants (99.0%; 95% confidence interval [CI], 98.3%-99.7%) maintained NmA-specific rSBA titers ≥8, the accepted threshold for protection; 98.6% (95% CI, 97.8%-99.4%) had titers ≥128, and 89.5% (95% CI, 87.4%-91.6%) had titers ≥1024. The rSBA GMTs were significantly higher in females than in males aged <18 years at vaccination (P <. 0001). NmA-specific IgG levels ≥2 μg/mL were found in 88.5% (95% CI, 86.3%-90.7%) of participants. Conclusions. Two years after PsA-TT introduction, a very high proportion of the population targeted for vaccination maintains high antibody titers against NmA. Assessing the duration of protection provided by PsA-TT is a priority for implementing evidence-based vaccination strategies. Representative, population-based seroprevalence studies complement clinical trials and provide this key evidence.
AB - Background. In 2010, Africa's first preventive meningococcal mass vaccination campaign was launched using a newly developed Neisseria meningitidis group A (NmA) polysaccharide-tetanus toxoid conjugate vaccine, PsA-TT (MenAfriVac), designed specifically for the meningitis belt. Given PsA-TT's recent introduction, the duration of protection against meningococcal group A is unknown. Methods. We conducted a household-based, age-stratified seroprevalence survey in Bamako, Mali, in 2012, 2 years after the vaccination campaign targeted all 1- to 29-year-olds. Randomly selected participants who had been eligible for PsA-TT provided a blood sample and responded to a questionnaire. Sera were analyzed to assess NmA-specific serum bactericidal antibody titers using rabbit complement (rSBA) and NmA-specific immunoglobulin G (IgG) by enzyme-linked immunosorbent assay. The proportion of participants putatively protected and the age group- and sex-specific rSBA geometric mean titers (GMTs) and IgG geometric mean concentrations (GMCs) were determined. Results. Two years postvaccination, nearly all of the 800 participants (99.0%; 95% confidence interval [CI], 98.3%-99.7%) maintained NmA-specific rSBA titers ≥8, the accepted threshold for protection; 98.6% (95% CI, 97.8%-99.4%) had titers ≥128, and 89.5% (95% CI, 87.4%-91.6%) had titers ≥1024. The rSBA GMTs were significantly higher in females than in males aged <18 years at vaccination (P <. 0001). NmA-specific IgG levels ≥2 μg/mL were found in 88.5% (95% CI, 86.3%-90.7%) of participants. Conclusions. Two years after PsA-TT introduction, a very high proportion of the population targeted for vaccination maintains high antibody titers against NmA. Assessing the duration of protection provided by PsA-TT is a priority for implementing evidence-based vaccination strategies. Representative, population-based seroprevalence studies complement clinical trials and provide this key evidence.
KW - Africa
KW - immunity
KW - meningococcal vaccines
KW - seroprevalence
UR - http://www.scopus.com/inward/record.url?scp=84947572467&partnerID=8YFLogxK
U2 - 10.1093/cid/civ602
DO - 10.1093/cid/civ602
M3 - Article
C2 - 26553687
AN - SCOPUS:84947572467
SN - 1058-4838
VL - 61
SP - S547-S553
JO - Clinical Infectious Diseases
JF - Clinical Infectious Diseases
ER -
