Association between long-term exposure to air pollutants and IgG antibody levels following SARS-CoV-2 breakthrough infections: a cross-sectional study

Objective To investigate the association between long-term exposure to air pollutants and immunoglobulin G (IgG) antibody levels in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) breakthrough infection cases, providing evidence for revealing the impacts of environmental factors on post-infection immune responses.

Methods In March 2023, a combined convenience and stratified random sampling strategy was employed to survey community residents in 14 districts and counties of Yichang city, Hubei province. Questionnaire data and IgG measurements were obtained, and 3 885 vaccinated individuals with SARS-CoV-2 breakthrough infections were included in the analysis. Residential addresses were decoded to latitude and longitude. Publicly available environmental databases were used to estimate long-term exposure to fine particulate matter (PM_2.5), inhalable particulate matter (PM₁₀), ultrafine particulate matter (PM₁), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), carbon monoxide (CO), temperature, relative humidity, and population density. Multivariate linear regression models were employed to evaluate the effects of long-term pollutant exposure on IgG levels.

Results Per interquartile range increase in PM₁ and NO₂ was associated with –2.83% (95%CI: –5.22% to –0.45%) and –3.17% (95%CI: –5.71% to –0.63%) changes in IgG antibody levels, respectively. Combined exposure to PM₁ and NO₂ was associated with a –1.49% (95%CI: –2.89% to –0.10%) change in IgG antibody level, with NO₂ contributing a higher proportion (57.0%) to the overall effect. Negative associations of PM₁ and NO₂ with IgG levels were more pronounced among individuals aged ≥ 60 years, smokers, and those with a time interval ≥ 12 months between the last vaccination and infection (all P_interaction < 0.05).

Conclusions Long-term exposure to PM₁ and NO₂ may impair the immune response following SARS-CoV-2 breakthrough infection. Individuals aged ≥ 60 years, smokers, and those with extended intervals since last vaccination are predisposed to weaker immune responses.