Elsevier

Vaccine

Volume 30, Issue 46, 12 October 2012, Pages 6521-6526
Vaccine

Immune response to tetanus booster in infants aged 15 months born prematurely with very low birth weight

https://doi.org/10.1016/j.vaccine.2012.08.056Get rights and content
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Abstract

Objectives

To compare humoral and cellular immune responses to tetanus booster vaccination in infants born prematurely with those born at full term and identify factors associated with the humoral response.

Methods

A prospective study was carried out on children born prematurely and with a birth weight <1500 g and with infants born at full term. At 15 months (pre-vaccination) and 18 months (post-vaccination), anti-tetanus antibodies were measured by ELISA; the intracellular interferon-gamma percentages of CD4+ T and CD8+ T cells after in vitro stimulation with tetanus toxoid were determined by flow cytometry. Chi-squared or Fisher's exact test was used to compare categorical variables. Student's t-test or Mann–Whitney test was used to compare numerical variables. Regression analysis was performed to determine factors associated with humoral immunity. Statistical significance was considered if p < 0.05.

Results

Sixty-four premature and 54 full-term infants were studied. The proportion of children immune against tetanus at 15 and 18 months was similar in both groups. The geometric mean of the antibodies was lower among the premature children at 15 months (p = 0.025) and was similar in both groups at 18 months (p = 0.852). The percentages of CD4+ and CD8+ T cells expressing intracellular IFN-γ were similar in both groups at 15 and 18 months. Gestational age <32 weeks was associated with a reduction of −0.116 IU/mL in the level of antibodies at 15 months. Breastfeeding >6 months was associated with a 3.5-fold greater chance of optimal protective (≥0.1 IU/mL) antibody level against tetanus at 15 months and an increase of 0.956 IU/mL in the level of antibodies at 18 months.

Conclusions

Humoral and cellular response following a tetanus booster was similar in both groups. Premature infants exhibited lower levels of anti-tetanus antibodies at 15 months of age, with the lowest levels in those born at a gestational age of less than 32 weeks. Breastfeeding was associated with greater levels of antibody against tetanus.

Highlights

► Preterm infants had lower antibody levels before tetanus booster at 15 months. ► Breastfeeding was associated with higher tetanus antibody levels before booster dose. ► Lower antibody levels were found in infants born before 32 weeks of gestation. ► Preterm and full term infants had similar immune response after tetanus booster dose.

Keywords

Premature infant
Immunization
Tetanus toxoid
Humoral immunity
Cellular immunity

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