Abstract
BACKGROUND: Under-vaccination is undoubtedly driving recent worldwide measles outbreaks, but undernutrition may also be playing a role in low- and middle-income countries. Studies have shown reduced immune response to vaccines in undernourished children but few have followed children beyond infancy, when they are more likely to be exposed to infectious diseases. METHODS: In the Venda Health Examination of Mothers, Babies and the Environment (VHEMBE) South African birth cohort study, we examined the relationship between undernutrition, as measured by stunting and other growth measures, and vaccine-specific serum antibody level to three different vaccine types: measles, tetanus and Haemophilus influenzae type b (Hib). We included 621 fully-vaccinated children with anthropometric measurements at ages 1, 2, and 3.5 years and antibody levels at 3.5 and 5 years. RESULTS: At 5 years of age, 90.4% of fully-vaccinated children were protected against measles, 66.7% against tetanus, and 56.1% against Hib. Children who were stunted or had any indicator of diminished growth at 3.5 years averaged a 24.1% (95% CI = -44.2, 0.6) or a 27.2% (95% CI = -45.1, -1.3) lower antibody titer for measles, respectively, relative to those with normal growth. In addition, girls, but not boys, with any indicator of diminished growth at 3.5 years averaged a 36.8% (-59.3, -7.0) lower antibody titer for tetanus. We found no association between undernutrition and Hib antibody titers. CONCLUSIONS: Early life undernutrition may be associated with lower induction or persistence of antibody responses to certain vaccines. Addressing child undernutrition may improve vaccine efficacy and reduce the burden of vaccine-preventable diseases.