Evaluation of serotype-specific immunity to Streptococcus pneumoniae in pregnant women and cord blood of infants: impact of race and ethnicity.

BACKGROUND

Although invasive pneumococcal disease (IPD) has significantly decreased in children since the introduction of the pneumococcal conjugate vaccine, instances of IPD from non-PCV7 serotypes have increased. Concerns remain regarding the risk for IPD during the neonatal period. Our objective was to measure quantitative antibody levels to 16 serotypes of Streptococcus pneumoniae in pregnant non-Hispanic black, non-Hispanic white, and Hispanic mothers, and in cord blood samples.

METHODS

Antibody levels were evaluated by Luminex assay.

RESULTS

Forty-two percent of all mothers had protective (-0.35 microg/mL) antibody levels to 16 serotypes. Hispanic mothers were most likely to possess protective antibody levels for 12 serotypes but were less likely to possess protective antibody levels for serotypes 9V, 12F, and 18C, compared to non-Hispanic white or black mothers. Thirty-three percent of cord blood samples demonstrated protective antibody levels. Hispanic infants had a higher prevalence of protective antibodies to all serotypes except 11A, 14, 18C, and 23F. Non-Hispanic black infants had a higher prevalence of protective immunity to serotypes 11A, 14, and 18C, and non-Hispanic white infants to only serotype 23F.

CONCLUSIONS

Hispanic mothers and their infants have a higher prevalence of protective immunity to most serotypes of S pneumoniae, compared to white or black mothers/infants. We found no evidence of a lower prevalence of protective immunity to specific serotypes in non-Hispanic black vs. non-Hispanic white infants that might account for the reported higher incidence of IPDs in blacks. Environmental factors in Hispanic mothers may be responsible for their enhanced level of immunity. A significant number of cord blood samples had inadequate levels of protective immunity to a variety of S pneumoniae serotypes.