Among a sample of South Asians recruited primarily from a designated hot spot in the GTA, we report a seroprevalence of SARS-CoV-2 of 23.6% (95% CI: 20.8 to 26.4), which is standardized by age and sex to the Ontario South Asian population. The range in seropositivity using the strict definition to lenient definition was 22% to 27%. The risk of bias assessment was classified as moderate, attributed to the non-probability sampling method. This report confirms other sources of evidence that racialized groups in general, as well as South Asians, specifically in the GTA, represent a high-risk group for SARS-CoV-2 infection (7). Since it utilizes serological testing, it captures infection rate more comprehensively than routine data sources, which rely on SARS-CoV-2 infection PCR testing.

Prior to the COVID-19 pandemic, ethnicity data are not routinely collected or made publicly available in Canada (16). As a surrogate, in areas where a single ethnic group is concentrated, infection and hospitalization rates can be examined by postal code, and then inferred to be representative of high-density ethnic populations (6). However, our data provide direct evidence of the high infection rate suffered by South Asians in the Peel Region. The reasons for this are multiple, and include socio-cultural factors including socioeconomic inequity, multigenerational households, barriers to accessing healthcare including SARS-CoV-2 testing, and the higher percentage of workers who were essential workers in factories, manufacturing, Amazon Inc. centres, and the trucking industry (17-19). Immigrants are overrepresented in meat, food and beverage processing plants, trucking, and in health and long-term care as nurses’ aides and orderlies. The reasons for overrepresentation include the low pay and lack of benefits and protections, features not desired by others who can pursue jobs in other sectors (20,21). Almost 33% of participants in our study reported doing essential work, although an additional 12% preferred not to answer this question, and 19% reported living in a multigenerational household, with an additional 12% preferring not to answer. Participants who indicated they “preferred not to answer” may reflect the stigmatization they may have felt during the initial waves of the pandemic. Therefore, the proportion of essential workers and those living in multigenerational households may be underestimates, especially considering our observation that participants who did not complete the follow-up survey where this information was collected, were more likely to be seropositive for SARS-CoV-2 (Supplementary Table 2).

Our seropositivity data mirrors the high infection rate when comparing FSAs in the City of Brampton and Peel Region (Figure 2). The seropositivity rate was higher in men compared to women, those with lower educational attainment, those living in Brampton, and in multigenerational households. Higher seropositivity of 2 to 3-fold has been reported in ethnic minority groups including Black and South Asian people compared to white people living in the United Kingdom (22,23). Compared to population-based seroprevalence studies conducted during the third wave of the pandemic in Canada such as the Canadian Blood Services with a seropositivity for previous infection of 3.95%, we observed a relatively high rate of seropositivity among South Asians in the GTA (23.6%) (24). However, a similarly high rate of seropositivity (22%) was reported among a cross-sectional study of 1,100 incarcerated men in Canada attributed to enhanced daily interactions in a congregate setting (25).

During the initial waves of the pandemic, it was unclear if standard public health messaging by public health officials at the Federal, Provincial, and local levels was reaching communities at high-risk such as South Asians (26). Our data, collected during the third pandemic wave, show that the top sources of information utilized by our cohort included information from healthcare providers or Public Health, traditional media sources, and social media (Figure 3). It is possible that our findings reflect the impact of activities of South Asian advocacy groups to raise awareness of health risks, and testing for SARS-CoV-2 infection, including provision of health information in multiple South Asian languages. For example, at the outset of the second wave of the pandemic, a physician-led group, named the South Asian COVID task force, opened a culturally sensitive testing centre in the Embassy Grand convention centre, with Punjabi signage and information translated into multiple South Asian languages, which was funded for and supported by Peel Public Health (27,28). Another advocacy group, the South Asian Health Network advocated for isolation centres; sick pay and time off work for testing and vaccination for essential workers, and COVID-19 information sessions regularly (29). Finally, Peel Public Health worked closely with community leaders to provide outreach onsite for essential workers, initiate testing at workplaces, and to develop mass vaccine centres with cultural sensitivity (16).

Finally, over 90% of the South Asian participants reported COVID-19 posed a major threat to the South Asian community, almost half reported their risk of acquiring COVID-19 was high due to their location, and more than 40% reported their risk was high due to their type of employment. In comparison, the minority of participants perceived their risk of COVID to be due to their lifestyle, such as socializing, or to their housing situation.

Limitations of our analysis include recruitment from vaccination centres, which may attract more health-conscious individuals, the selection of whom could lead to an underestimate of the true seroprevalence (Supplementary Table 1). Further, the history of COVID-19 infection was based on self-reporting which is less reliable than laboratory confirmed diagnosis.