Fine particulate matter, nitrogen dioxide, and Tdap vaccine antibody levels in Mexican children

Objective: Existing research suggests that vaccine antibody response can be attenuated by environmental factors, but limited studies have assessed the association with air pollutants. We hypothesize that air pollution exposure early in life can alter immune response in later childhood.

Methods: We obtained serum antibody levels of tetanus, diphtheria, and pertussis measured in vaccinated children ages 4-6 years from the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) cohort in Mexico. We constructed 1-km² fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) models over the Mexico City Metropolitan Area, which we geocoded to participants’ home addresses. We employed linear mixed-effects models to examine the association between early life exposure to PM_2.5 and NO₂, measured as averaged pollutants exposures in the first year of life, and log-transformed tetanus, diphtheria, and pertussis (Tdap) antibody levels in later childhood (ages 4-6). Models included random intercepts for participant and were adjusted for temperature, sex, child age at blood draw, maternal age at birth, BMI, and socioeconomic status.

Results: 299 children contributed to antibody levels at 4 years (n=287) and 6 years (n=12). We observed negative but imprecise associations with both pollutants. Per 1 µg/m³ increase in one-year postnatal PM_2.5, Tdap antibody levels decreased by 3.47% (95%CI: -7.35, 0.57%), 3.37% (95%CI: -7.18, 0.60%), and 2.56% (95%CI: -6.93, 2.02%) respectively. Per 1 µg/m³ increase in one-year postnatal NO₂, Tdap antibody levels decreased by 3.89% (95%CI: -7.22, -0.45%), 3.51% (95%CI: -6.81, -0.09%), and 1.93% (95%CI: -5.74, 2.04%) respectively.

Conclusion: We found preliminary evidence suggesting decreased antibody levels in response to postnatal PM_2.5 and NO₂ exposure, though not all results were significant. Additional work is necessary to explore associations for different types of routine vaccinations and at different critical time windows.