Urban Form and Health Status in Gauteng, South Africa

Residential spatial impact on increased susceptibility to coronavirus transmission is mainly reported in communities residing in high-rise residential buildings and slums or informal settlements. This study investigates differential SARS-CoV2 infection according to urban form and site—high-density apartments (HDA) in Hillbrow, Johannesburg, formal township housing (FTH), and formal dwellings’ backyards (FTB) in Atteridgeville, Tshwane, and informal settlement dwellings (ISD) in Melusi, Tshwane—to inform precautionary strategies. The study was conducted as a randomized cross-sectional household survey with serological testing (n = 3053). Data was collected between 23 March and 10 October 2021 across sites during overlapping periods. Previous SARS-CoV2 infection was assessed by Wantai SARS-CoV-2 Ab ELISA and Elecsys Anti-SARS-CoV-2 ELISA testing. Logistic regression analyses assessed the association between seropositivity and demographic variables in the study population during two periods—Period 1: following the Beta wave up until 31 May, at the start of the Delta-variant wave—and Period 2: commencing thereafter. Period 1 comprises mainly ISD and FTD samples and Period 2, HDA and FTD samples. Seroprevalence was highest in HDA (85%), lowest in ISD (35%), and similar in formal township dwellings (FTD) (FTH 45%; FTB 47%), and appeared to increase over time, irrespective of urban form and time during the pandemic. Multivariate analysis showed increased odds for seropositivity regarding the urban form, period, age group, and sex. Contrary to the previous observations, ISD are least susceptible to SARS-CoV2 infection, and younger age and female sex contribute significantly to seropositivity. Additional urban form-associated factors like contact rates and mobility need to be considered to better understand the relationship with health.