Trends of SARS-CoV-2 antibody prevalence in selected regions across Ghana

Abstract

To estimate the level of community exposure to SARS-CoV-2 in Ghana, we conducted phased seroprevalence studies of 2729 participants in selected locations across Ghana. Phase I screening (August 2020) covered a total of 1305 individuals screened at major markets/lorry stations, major shopping malls, hospitals and research institutions involved in COVID-19 work. The screening was performed using a strip-in-cassette lateral flow type Rapid Diagnostic Test (RDT) kit that simultaneously and separately detected IgM and IgG antibodies against SARS-CoV-2 nucleocapsid protein. In Phase I, 252/1305 (19%) tested positive for IgM or IgG or both. Exposure rate was significantly higher among individuals tested at markets/lorry stations (26.9%) compared to those at Shopping Malls (9.4%). The 41--60-years age group had the highest exposure rate (27.2%). People with only a basic level or no formal education had a higher exposure rate (26.2%) than those with tertiary level education (13.1%); and higher in informally employed workers (24.0%) than those in the formal sector (15.0%). Phases II and III screening activities in October and December 2020, respectively, showed no evidence of increased seroprevalence, indicating either a reduced transmission rate or loss of antibody expression in a subset of the participants. The Upper East region has the lowest exposure rate, with only 4 of 200 participants (2%) seropositivity. Phase IV screening in February 2021 showed that exposure rates in the upper income earners (26.2%) had almost doubled since August 2020, reflective of Ghana s second wave of symptomatic COVID-19 cases, which began in December 2020. The Phase IV results suggest that seroprevalence levels have become so high that the initial socioeconomic stratification of exposure has been lost. Overall, the data indicates a much higher COVID-19 seroprevalence in the Greater Accra Region than was officially acknowledged, likely implying a considerably lower case fatality rate than the current national figure of 0.84%. Additionally, the high exposure levels seen in the communities suggest that COVID-19 in Ghana still predominantly presents with none-to-mild symptoms. Our results lay the foundation for more extensive SARS-CoV-2 surveillance in Ghana and the West African sub-region, including deploying rapid antigen test kits in concert to determine the actual infection burden since antibody development lags infection.