Air pollution lowers COVID-19 vaccine immune response

By Neha MathurApr 9 2023Reviewed by Lily Ramsey, LLM

In a recent study published in the journal Environmental Health Perspectives, researchers performed a population-level cohort study in Catalonia, Spain, to evaluate the association between exposure to air pollution for a prolonged duration and coronavirus disease 2019 (COVID-19) vaccine-induced antibody response.

Study: Long-Term Exposure to Air Pollution and COVID-19 Vaccine Antibody Response in a General Population Cohort (COVICAT Study, Catalonia). Image Credit: Toa55 / Shutterstock

Background

Previous studies have shown that air pollutants trigger aberrations in multiple classes of immune cells, thereby exacerbating asthma and chronic respiratory and cardiovascular diseases. Studies have also found that chronic inflammation induced by air pollution has a negative effect on vaccine efficacy, including that of the COVID-19 vaccine. However, there is limited scientific evidence of the long-term effects of air pollution on vaccine response.

About the study

In the present study, researchers analyzed blood samples of 927 COVID-19 vaccinated participants to detect immunoglobulin G (IgG), IgM, and IgA antibodies against a panel of five severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens using a high-throughput multiplex quantitative suspension array technology.

Note that research on immunological responses to COVID-19 vaccines, similarly to other vaccines, has remained focused on IgG responses. However, in this study, researchers measured IgM antibodies elicited by vaccination in participants sampled within the first month after receiving the first dose. On the contrary, they analyzed the IgG/IgA levels of all participants regardless of sampling time post-vaccination.

Next, the team exposure levels of the study participants during 2018-2019 (pre-pandemic time) to particulate matter 2.5 (PM_2.5), nitrogen dioxide (NO₂), ozone (O₃), and black carbon (BC) using models based on the Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) project. PM_2.5 are tiny particles less than or equal to 2.5 micrometers in aerodynamic diameter.

The team adjusted these estimates for the area- and individual-level covariates, vaccine type and doses, time since vaccination, and infection status. Finally, they utilized generalized additive models to investigate the association between air pollutants and antibodies accounting for time since vaccination.

Likewise, the team used linear regression models to examine the association between air pollution levels and the log₁₀-transformed antibody levels and expressed results as the percentage change in the geometric mean (GM) and 95% confidence intervals (CIs). After continuously modeling air pollutants, the team also estimated and reported an interquartile range (IQR) for each pollutant.

Study findings

The authors observed an association between exposure to air pollution and COVID-19 vaccine antibody response among participants with no COVID-19 history. In particular, exposure to PM_2.5, BC, and NO2 decreased vaccine antibody responses by 5 to 10% after adjusting for confounders. They had ∼10% lower antibody responses to S antigens triggered by the vaccines, highlighting the role of multiple immune pathways through which air pollution exerts its effects to cause chronic diseases.

However, future studies should use long-term prospective data to evaluate this decrease in antibody response to the future risk of COVID-19. Similarly, studies should investigate the effects of air pollution on immunization for other diseases.

Moreover, the observed decrease lasted for many months (persistent) in participants exposed to above-average air pollution levels. Furthermore, the authors observed this decrease in early responses (IgM levels), and late responses reflected as IgG levels.

These findings on air pollution exposure were consistent with pre-existing evidence suggesting that the persistence of immunotoxicants, such as polychlorinated biphenyls (PCBs), decreases vaccine response in children. The study used a multiplex assay, which helped the researchers distinguish previously infected participants from those who remained uninfected. However, the researchers could not determine insignificant differences in response to three SARS-CoV-2 antigens, given that they were closely correlated.

Conclusions

The authors did not investigate whether the observed decline in antibody responses to COVID-19 vaccination was associated with the risk of breakthrough SARS-CoV-2 infections and their severity. The effect of pollutants on vaccine responses could likely vary and get masked among those infected again.

As the COVID-19 pandemic and vaccination campaigns evolve, more people will develop immunity through a combination of infection and vaccination, termed hybrid immunity. Future research should investigate the role of long-term exposure to air pollution on this hybrid immunity.

Overall, the study findings add to the evidence of the adverse effects of air pollution even in geographical regions where air pollution is relatively low, e.g., Western Europe. Furthermore, it highlights the need for stricter measures to control exposure to air pollution per the World Health Organization recommendations.