Area-level social and economic factors and the local incidence of SARS-CoV-2 infections in Victoria during 2020

Abstract

Objective: To examine associations between area-level socio-economic factors and the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Victoria during 2020.

Design, setting: Population-level ecological study of the incidence of SARS-CoV-2 infections in Victoria, by postcode, 1 March - 13 August 2020.

Main outcome measures: Relationships between the incidence of SARS-CoV-2 infections by postcode (Department of Health and Human Services data published on The Age website), and demographic, education level, ethnic background, economic and employment-related factors, housing-related factors, and social disadvantage (Australian Bureau of Statistics data for 2014-19), expressed as incidence rate ratios (IRRs).

Results: During the study period, 15 482 SARS-CoV-2 infections with associated postcodes were recorded in Victoria. Incidence was higher for metropolitan than regional postcodes (418.3 v 62 infections per 100 000 population; IRR, 6.2; 95% CI, 4.6-8.2). In regional postcodes, incidence rose with mean household size (per person: IRR, 7.30; 95% CI, 4.37-12.2), unemployment proportion (per percentage point: IRR, 1.50; 95% CI, 1.33-1.69), and proportions for whom rent (IRR, 1.15; 95% CI, 1.07-1.22) or mortgage repayments (IRR, 1.22; 95% CI, 1.15-1.28) exceeded 30% of household income. In metropolitan areas, incidence increased with unemployment proportion (IRR, 1.14; 95% CI, 1.05-1.23) and proportion without paid leave (IRR, 1.22; 95% CI, 1.02-1.45). Incidence also increased with proportion speaking languages other than English at home (regional: IRR, 1.08; 95% CI, 1.06-1.11; metropolitan: IRR, 1.01; 95% CI, 1.002-1.02) and with Indigenous Australian proportion (metropolitan only: IRR, 1.91; 95% CI, 1.10-2.73).

Conclusions: Socio-economic factors may have contributed to the non-homogeneous incidence of SARS-CoV-2 infections across Victoria during 2020.

Keywords: COVID-19; Cultural competency; Health policy; Public health; Social determinants of health.

Grey circles indicate unmeasured mechanisms of transmission that link population factors (white) with the postcode incidence of SARS‐CoV‐2 infections. These factors interact with factors influencing workplace and social transmission because of differences in social networks, health literacy, and financial and housing conditions. Demographic characteristics also influence transmission; for example, the median age of the Indigenous population is lower than for other Australians. Postcodes with a larger proportion of working age people are likely to have larger median household sizes and to include younger children than areas with larger proportions of people of retirement age.