In this retrospective chart review study using neighborhood socioeconomic data collected from two Toronto-area COVID-19 Assessment Centres, neighbourhood income and immigration levels were associated with COVID-19 test positivity but in opposing directions. People living in the lowest income and highest immigrant neighbourhoods were more likely to test positive than those from higher income neighbourhoods or lower immigrant neighbourhoods. However, individuals living in higher risk communities were generally less likely to be tested than those living in more affluent communities, where the risk of contracting COVID-19 was lower.
Our findings of associations for test positivity are consistent with initial Ontario-wide studies [12, 28] and from other studies across multiple jurisdictions [29, 30]. The finding of higher COVID-19 test positivity among individuals living in neighbourhoods with higher proportions of immigrants and newcomers has also been reported elsewhere, such as in New York City , and Montreal, Quebec . These findings have been attributed to a higher proportion of essential workers, who often live in low income, marginalized neighbourhoods, and work in higher risk occupational settings, (e.g., long-term care centres, food processing plants, warehouses and factories) [33, 34], where public health measures may be lax.
Low income and immigration are often associated with poorer access to health care. In our research, only low income was associated with decreased testing, while people living in high immigrant neighbourhoods were more likely to be tested. Findings from other studies on testing and income are conflicting. A New York City study found no association , whereas a survey of US adults in 2020 found that lower income was associated with perceived difficulty with accessing testing . Our finding of increased testing volume in high immigrant neighbourhoods contrasts with an Ontario provincial report which found that immigrants overall had lower COVID-19 test rates than the general population, with an exception for the subgroup of immigrants employed as economic caregivers . It is possible that our findings reflect the catchment area of the two assessment centres. WCH is located in the ‘Bay Street Corridor’ neighbourhood which is more densely populated than the ‘Westminster-Branson’ neighbourhood where the NYGH is located (14,000 people/km2 vs 7000/ km2) but both have similar total populations (25,000 vs 26,000, respectively). The Bay Street Corridor neighbourhood has lower recent immigrant population (41% vs 70%); higher proportion of people living in poverty (39% vs 27.2%); more renters (79% vs 60%); more people living in higher-density housing such as apartments (98% vs 76%); and an overall higher education level (> undergraduate university degree 79% vs 44%) . However, anyone could seek testing at the centres and people testing did not necessarily live near them.
Many testing approaches to limit the spread of COVID-19 have been suggested in the literature, including testing everyone in a population either once  or recurrently, such as weekly . Rapid tests have also been recommended, particularly for higher-incidence settings such as high-risk work-places, but their uptake in Canada has been limited . The optimal strategy is not known and is affected by local outbreak conditions and system capacity for testing. There are inevitable limitations in system capacity with widespread population testing, as demonstrated by the ‘backlog’ of almost 100,000 collected samples waiting to be processed in Fall 2020. The report of the Canadian COVID-19 Expert Panel on Testing and Screening Advisory Panel recommended “context specific strategies to improve access to testing and screening in underserved and higher risk communities” . The US Centres for Disease Control (CDC) has a framework for maintaining a functioning public health response to COVID-19 which includes recognizing that testing should be prioritized for symptomatic contacts of positive cases, as well as those who are most likely to be infectious, rather than specimens of asymptomatic contacts and those with lower risk exposures .
Our finding that people living in ‘high income’ neighbourhoods had more tests than those in ‘low income’ neighbourhoods, although the latter had higher positivity rates, represents a mismatch between testing needs and COVID-19 risk. To date, Ontario’s testing strategies have been focused primarily on setting out criteria for testing, then disseminating recommendations through media. Throughout the pandemic, criteria around who is ‘eligible’ or ‘recommended’ for SARS-CoV-2 testing have varied not only with the passing of time but also between assessment centres. Within this changing landscape, individuals must understand criteria for testing, know how to access testing and have the time and ability to get to a testing centre. It is not surprising then, that people with financial challenges would have more difficulty accessing testing than those who have more resources.
Given the higher positivity rates among people in ‘lower income’ and ‘higher immigrant’ areas, we question the appropriateness of our province’s testing approach during the study period April–September 2020, given that it did not specifically prioritize high-risk neighbourhoods. We note that our study occurred when test positivity was low, at roughly 2%. Since the start of the third wave in Ontario, COVID-19 test positivity rates have ranged from 10% to over 22% (e.g., Brampton) in some regions of the Greater Toronto Area (GTA) . There are some ‘local’ initiatives, such as ‘pop-up’ testing sites to higher risk neighbourhoods, coordinated through community health centres, Ontario Health Teams , clinical teams from local hospitals  or through mobile buses . Community engagement and mobilization efforts with volunteers from both the health and social services sectors and local community leaders have tried to ensure that COVID-19 testing is more accessible in Canada . Options for improving accessibility include situating centres in locations that are accessible via public transport or in high-traffic areas (e.g. cultural or religious centres, near grocery stores), and offering evenings/weekend timings to be more accessible for individuals with employment, financial, or childcare-related barriers. Advertising for testing locations and requirements should be available in multiple languages for patients who speak English as a second language, in addition to offering trained medical interpreters [45, 46].
The main limitation of our study is the possibility that people living in lower income neighbourhoods and/or lower immigrant neighbourhoods disproportionately attended assessment centres other than the two included in this study. While this is possible, the direction of the impact would depend on the positivity rate: for example, if people in lower income neighbourhoods who were positive, were more likely to attend other assessment centres, than this would decrease the magnitude of the association between income and COVID-19 positivity in this study. If people living in higher immigration level neighbourhoods who were also positive were more likely to attend other assessment centres, then this would increase the magnitude of the association between immigration status and test positivity here. Our inclusion of assessment centres in neighbourhoods at different income/immigration levels attempted to limit the impact of this, and there is no specific reason to suspect that there were these systematic differences in attendance at different assessment centres. The nearest assessment centre to the NYGH site was 7 km away; there were multiple assessment centres within 1 km of WCH. People may have preferentially attended centres close to their workplace, but that is unlikely to cause substantial systematic differences in positivity rate or income/immigration neighbourhood status. The other possibility is that people living in lower income neighbourhoods were never tested, which would support our finding of a testing/risk mismatch. Assessment centres did not collect race and immigration status data, nor occupation. Despite these being important demographic factors associated with COVID-19, there are no requirements to collect these data in Canada, which has limited our ability to identify those at highest risk and allocate resources, such as testing, appropriately . The results need to be interpreted in the context of changing testing criteria and epidemiology over time (Table 1) . In addition, it is also important to note that income and immigration status may be proxies for other environmental features that may promote infections with COVID-19, such as population density or housing and working conditions. Furthermore, as our immigration-related data was solely based on foreign-born status, future studies may wish to investigate the full dynamics around immigrations, including second-generation or third-generation families. Finally, it is important to note that our data were collected in 2020. Given the rapidly evolving situation of the pandemic, our findings may not reflect the most recent waves and other contexts.