Date of Award

January 2026

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Catherine Buck

Second Advisor

Inci Yildirim

Abstract

Background: In adults, excess adiposity is associated with impaired immune function, but thisrelationship is not well understood among infants and young children under the age of 5. Objective: To examine the association between adiposity at birth and the risk of developing laboratory-confirmed viral infections through early childhood in term and preterm infants. Methods: Term and preterm (30-36 weeks gestational age) infants were recruited at birth, and underwent body composition assessments during hospitalization. Electronic medical records were reviewed to identify laboratory-confirmed viral respiratory infections (influenza A/B, SARS-CoV-2, respiratory syncytial virus, and other respiratory viruses) through early childhood. Associations between adiposity measures (weight Z-score, mid-upper arm circumference, subscapular and triceps skinfold thickness, and body fat percentage) and viral infection risk were examined using Poisson regression models to estimate incidence rate ratios (IRR). Results: Among 150 infants in the initial cohort, 86 with any viral testing were included (median follow-up 49.3 months, IQR 43.2-55.1). A total of 607 viral tests were performed. Positivity rates were 8.7% for influenza A, 0% for influenza B, 11.7% for SARS-CoV-2, 21.1% for RSV, and 84.7% for other respiratory viruses. SARS-CoV-2 infections occurred earlier and more frequently in life, whereas influenza occurred later in follow-up. In adjusted Poisson regression models, subscapular skinfold thickness was weakly associated with infection risk (IRR 1.06, 95% CI 0.92-1.22); similar null associations were observed across other adiposity measures. Conclusions: In this cohort, adiposity measures at discharge were not associated with viral infection incidence in early childhood. SARS-CoV-2 infections tended to occur earlier in infancy and influenza later in follow-up, and modest differences in infection risk over time were observed by adiposity. These findings suggest that infant adiposity may not meaningfully influence early-life viral infection susceptibility, though further research in larger cohorts is needed to improve precision and evaluate whether associations emerge later in childhood.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 09/16/2027

Download

Share

COinS