Higher SARS-CoV-2 Seroprevalence in Workers with Lower Socioeconomic Status in Cape Town, South Africa.

Abstract

Background: South Africa has a high degree of inequality between population groups. The first wave of COVID-19 may have affected people in lower socioeconomic groups worse than the affluent. The SARS-CoV-2 seroprevalence and the specificity of anti-SARS-CoV-2 antibody tests in South Africa is not known. Methods: We tested 405 volunteers representing all socioeconomic strata from the workforce of a popular shopping and tourist complex in central Cape Town with the Abbott SARS-CoV-2 IgG assay. We assessed the association between antibody positivity and COVID-19 symptom status, medical history, and sociodemographic variables. We tested 137 serum samples from healthy controls collected in Cape Town prior to the COVID-19 pandemic, to confirm the specificity of the assay in the local population.Results: Of the 405 volunteers tested one month after the first peak of the epidemic in Cape Town, 96(23.7%) were SARS-CoV-2 IgG positive. Of those who tested positive, 46(47.9%) reported no symptoms of COVID-19 in the previous 6 months. Seropositivity was significantly associated with living in informal housing, residing in a subdistrict with low income-per household, and having a low-earning occupation. The specificity of the assay was 98.54%(95%CI 94.82%-99.82%) in the pre-COVID controls.Conclusions: There is a high background seroprevalence in Cape Town, particularly in people of lower socioeconomic status. Half of cases are asymptomatic, and therefore undiagnosed by local testing strategies. These results cannot be explained by low assay specificity.

Prevalence of anti-SARS-CoV-2 antibodies among blood donors in Northern Cape, KwaZulu-Natal, Eastern Cape, and Free State provinces of South Africa in January 2021.

“…These significant differences most likely can be explained by historically based socio-economic factors which hinder the implementation of COVID-19 preventative measures at a community level. Previous seroprevalence estimates from South Africa, specifically the Western Cape province (not included in our analysis), earlier in the epidemic found: 1) a very high prevalence (30-40 percent) among pregnant women attending state sector antenatal care, and people living with HIV presenting for routine viral load assessment (7); and 2) higher prevalence among workers with lower socioeconomic status (8). A review of population-based seroprevalence studies in Europe, America and Asia reported a seroprevalence range of <0.1% to more than 20% in the different regions (2).…”

Seroprevalence of anti‐SARS‐CoV‐2 antibodies in Africa: A systematic review and meta‐analysis

“…(2021) in RSA found that seroprevalence was higher in participants with hypertension (15 [15.6%]) than diabetes (10 [10.4%]). 21 , 42 Alemu et al. (2020), in Ethiopia found that prevalence was higher in married 13 (9.8%), compared to single 9 (6.8%), or divorced/widowed 1 (2.8%).…”

Higher COVID-19 mortality in low-income communities in the City of Cape Town – a descriptive ecological study

“…Individuals in low-income communities with crowded housing, a reliance on public transport and higher numbers of essential workers are less able to implement and maintain social distancing and non-pharmaceutical interventions (NPIs) 7 . And they therefore are more likely to get infected with COVID-19, as demonstrated in several South African seroprevalence studies [15][16][17] .…”

“…While the authors note the limitations of using race as a proxy for socio-economic status, their study highlights the limitations of NPIs in communities with economic deprivation and high population density, or conversely how effective NPIs can be when they are feasible 15 . A study on shopping mall workers in Cape Town found a high seroprevalence was associated with informal housing, living in a sub-district with a low-income per household and having a low-earning occupation 16 .…”