Equitable access to COVID-19 diagnostics: factors associated with the uptake of rapid antigen testing in Victoria, Australia, January - February 2022

Abstract

Background: Accessible and accurate diagnostics are critical to control communicable diseases. Uptake of COVID-19 rapid antigen (RA) testing requires physical and financial access to tests, knowledge about usage, motivation, and ability to report results. We sought to understand patterns of and factors associated with RA test uptake in Victoria during a period of high caseload, RA test promotion, and difficulty accessing RA and PCR testing. We hypothesise RA test uptake is indicated by the ratio of cases diagnosed by RA test (probable) to those diagnosed using PCR (confirmed) (p:c).

Methods: Analysing case records, trends in p:c were assessed, between regions, sex, age groups, socio-economic strata and cultural diversity. Logistic regression assessed associations between case classification, and median age, postcode-level socio-economic disadvantage, and proportion overseas-born.

Results: We included 591,789 cases. Mean p:c was lower in socio-economically disadvantaged areas (decile 1 + 2: 0.90 vs. decile 9 + 10: 1.10), and in postcodes where the overseas-born population was above the Victorian average (0.83 vs. 1.05). Conversely, p:c was higher in younger age groups; with no difference between sexes overall. In metropolitan Melbourne, odds of RA test usage increased as socio-economic disadvantage decreased (decile 9 + 10, aOR 1.40, 95%CI 1.37-1.43, vs. decile 1 + 2; p < .001), decreased for cases from areas with a higher overseas-born population (aOR 0.85, 0.83-0.86, p < .001), and with older age.

Conclusions: Reduced uptake of RA tests in Victoria is associated with socio-economic disadvantage, cultural diversity, and older age. Equitable access to COVID-19 diagnostics requires elimination of financial barriers, and greater engagement with culturally diverse and older groups. Inequitable RA test uptake may lead to case under-ascertainment, affecting resource allocation, effective control strategy development, in turn impacting COVID-19 morbidity and mortality, and could indicate relative engagement with response initiatives.

Keywords: COVID-19; Diagnostics; Engagement; Equity; Health equity; Health inequalities; Rapid antigen testing; Socio-economic disadvantage; Testing.