Ambient air pollution and risk of SARS-CoV-2 infection and of COVID-19 disease in a cohort study in Catalonia (COVICAT Cohort)

Abstract

BACKGROUND AND AIM: Air pollution has been associated with a higher risk of COVID-19 in ecological studies. We examined the association of pre-pandemic air pollution with SARS-CoV-2 infection, immunological response, and COVID-19 disease in a general population cohort. METHODS: 9,605 adult participants from a general population cohort in Catalonia were contacted post-lockdown in June-November 2020 and administered web- or telephone-based questionnaires. We drew blood samples from 4090 participants, and determined IgG, IgM, and IgA antibodies for five viral target antigens (Luminex assay). We defined disease as previous diagnoses or hospital admission with COVID-19, or reporting 4 or more COVID-19 symptoms. We used the ELAPSE model to assess annual pre-pandemic (2010) exposure to particulate matter (PM2.5), NO2, Black Carbon (BC), and O3. We calculated log-binomial Relative Risks (RR) adjusting for age, sex, type of questionnaire, individual and area-based socioeconomic status, and lifestyle factors. RESULTS:Of the 9,605 participants 481 (5.0%) had COVID-19 disease. Among those tested for SARS-Cov-2 antibodies, 743 (18.1%) had been infected. There were no associations between air pollutants and SARS-CoV-2 infection: increases in average annual levels of 5μg/m3 of NO2 and PM2.5 and 1μg/m3 of BC were associated with RRs (95%CI) of 1.02 (0.98-1.06), 1.07 (0.85-1.35) and 1.08 (0.92-1.29) respectively. Among infected participants, increasing air pollutant levels were associated with higher IgG responses. Air-pollutants were associated in the overall population with increased risk of COVID-19 disease with RRs of 1.07 (95%CI 1.02-1.11) for NO2, 1.45 (1.07-1.97) for PM2.5, and 1.28 (1.02-1.59 for BC. O3 was associated with a slightly decreased risk (RR=0.98, 0.97-1.00). We observed similar results among those infected. We observed slightly higher risks of COVID-19 disease associated with air-pollutants in obese participants and those with lower socioeconomic position. CONCLUSIONS:Exposure to pre-pandemic air-pollutants was associated with a higher risk of COVID-19 disease although not associated with a higher risk of SARS-CoV-2 infection. KEYWORDS: COVID-19, SARS-CoV-2, immunology, air-pollution, cohort