High prevalence of pre-existing serological cross-reactivity against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in sub-Saharan Africa

Objective: Significant morbidity and mortality have occurred in the USA, Europe, and Asia due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), whereas the numbers of infections and deaths in sub-Saharan Africa (SSA) have remained comparatively low. It has been hypothesized that exposure of the population in SSA to other coronaviruses prior to the COVID-19 pandemic resulted in some degree of cross-protection against SARS-CoV-2 infection and pathogenesis. We evaluated this hypothesis by comparing SARS-CoV-2 cross-reactive antibodies in pre-pandemic plasma samples collected from SSA and the USA. Method: Pre-COVID-19 pandemic plasma samples from SSA and the USA were collected and tested by immunofluorescence assay against the spike and nucleocapsid proteins of all known human coronaviruses (HCoVs). Results: The prevalence of SARS-CoV-2 serological cross-reactivity was significantly higher in samples from SSA compared with the USA. Most of these cross-reactive samples cross-recognized the SARS-CoV-2 nucleocapsid protein and the spike proteins of other HCoVs. Nucleocapsid proteins from HCoV-NL63 and HCoV-229E were detected in most samples, thereby implicating prior exposure to these two HCoVs as the likely source of cross-reactive antibodies against SARS-CoV-2. Conclusion: The low incidences of SARS-CoV-2 infection and disease in SSA appear to be correlated with the pre-pandemic serological cross-recognition of HCoVs, which are substantially more prevalent in SSA than the USA. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

Automated summary

The study found a higher prevalence of SARS-CoV-2 cross-reactive antibodies in pre-pandemic plasma samples from SSA compared to the USA, indicating potential cross-protection due to prior exposure to other coronaviruses in SSA. The detection of nucleocapsid proteins from HCoV-NL63 and HCoV-229E in most samples suggests these viruses as the likely sources of cross-reactive antibodies against SARS-CoV-2. The low incidence of SARS-CoV-2 infection and disease in SSA may be correlated with pre-pandemic serological cross-recognition of HCoVs, which are more prevalent in SSA than the USA.