Joint Impacts of Nutrition and Socioeconomic Status on SARS-CoV-2 Antibody Titer in a Prospective Birth Cohort in Brazil.

PurposeIn this study, we examine the joint effects of stunting and socioeconomic status (SES) on COVID-19 serostatus in Brazil and whether these patterns vary by COVID-19 vaccine status. MethodsWe use data from birth through the 7-year follow-up of the Pelotas 2015 birth cohort, including anthropometry, demographics, vaccination status, and COVID-19 antibody test results. We use linear regression models to examine the associations between SES (exposure) and stunting (effect modifier) on COVID-19 antibody titer among children who had not been vaccinated for COVID-19 (n=1,103) and among children who had been vaccinated (n=1,875). ResultsAll SES strata had a statistically identical probability of testing positive. While not statistically significant, stunted children who were unvaccinated tended to have lower COVID-19 titers (difference -0.10, 95% CI: -0.21,0.004) compared with children who were not stunted, and this difference was attenuated among stunted children who were vaccinated. Duration of school enrollment was associated with increased antibody titer, with each month being associated with a 0.17 unit higher increase in OD titer (95% CI: 0.15, 0.18). ConclusionsThis result may suggest that stunted children have poorer immune responses to natural infection and thus lower immunity, but vaccination can overcome this deficit. Future recommendations include population-wide follow-up vaccination, particularly for stunted children. Given increasing antibody titer with a longer duration of school attendance, primary COVID-19 vaccination and potential boosters may be useful for children prior to school entry to reduce the risk of natural infection.