Abstract
BACKGROUND: As immunity wanes and viral mutations continue, the risk of endemic SARS-CoV-2 breakthrough infections (BTIs) remains. Air pollution is considered a risk factor for respiratory infection, but evidence of its association with SARS-CoV-2 BTIs is limited. OBJECTIVES: We aimed to examine the effects of long-term exposure to air pollution on disease outcomes, immune responses, and antibody dynamics of SARS-CoV-2 BTIs. METHODS: We gathered data on self-reported SARS-CoV-2 infections through questionnaires and measured IgG antibody levels using serological assays from a total of 6,875 participants from the Yichang COVID-19 Antibody Longitudinal Survey cohort in China. Air pollutant exposure [particulate matter (PM) with an aerodynamic diameter ≤ 2.5 μm (PM2.5), PM with an aerodynamic diameter ≤ 10 μm (PM10), PM with an aerodynamic diameter ≤ 1 μm (PM1), SO2, NO2, O3, and CO] was quantified using validated models for the past 5 y (2018-2022). Logistic and linear regression models were applied to analyze the associations between air pollutant levels and SARS-CoV-2 BTIs, Long COVID, COVID-19 hospitalization, and antibody responses. Quantile g-computation was used to assess the combined effects of pollutant mixtures. A linear mixed model was used to evaluate the effect of air pollution on antibody dynamics. RESULTS: Per interquartile range (IQR) increase in PM2.5, SO2, NO2, and CO, the adjusted odds ratios (ORs) for SARS-CoV-2 BTIs were 1.65 [95% confidence interval (CI): 1.30, 2.08], 1.30 (95% CI: 1.12, 1.50), 1.63 (95% CI: 1.20, 2.20), and 1.24 (95% CI: 1.06, 1.45). The ORs for PM2.5 were 1.78 (95% CI: 1.07, 3.02) and 2.02 (95% CI: 1.18, 3.54) for Long COVID and hospitalization. Per IQR increase in PM1 and NO2, IgG antibody percentages decreased by - 2.31% (95% CI: - 4.49%, - 0.13%) and - 2.69% (95% CI: - 5.35%, - 0.03%). Effects were stronger in older adults, those with comorbidities, and the undervaccinated. The combined effect on SARS-CoV-2 BTIs was mainly driven by PM2.5 (59.4%), and the impact on IgG response was largely attributed to NO2 (63.7%). Exposure to the highest levels of PM2.5 (p = 0.002), PM1 (p < 0.001), and NO2 (p = 0.002) was associated with a faster IgG decline than the lowest. DISCUSSION: Long-term exposure to air pollution increases the risk of SARS-CoV-2 BTIs and disease severity while weakening the immune response, particularly for vulnerable populations. https://doi.org/10.1289/EHP15660.