Highlights • High prevalence of serological cross-reactivity against SARS-CoV-2 in pre-COVID-19 pandemic plasma samples from sub-Sahara Africa. • Pre-COVID-19 pandemic plasma displayed strong reactivity against other human coronaviruses. • Exposure to other coronaviruses may induce cross-reactive antibodies against SARS-CoV-2 in sub-Sahara Africa.
Objective Significant morbidity and mortality from SARS-CoV-2 has been experienced in America, Europe and Asia; whereas, the number of infections and deaths in sub-Sahara Africa (SSA) has remained comparatively low. One hypothesis is that population in SSA has been exposed to other coronaviruses prior to the COVID-19 pandemic and resulted in some degree of cross-protection against SARS-CoV-2 infection and pathogenesis. Our goal was to evaluate this hypothesis by comparing SARS-CoV-2 cross-reactive antibodies in pre-pandemic plasma samples collected from SSA and USA. Method Pre-COVID-19 pandemic plasma samples from SSA and USA were collected and tested by immunofluorescence assay against the spike and nucleocapid proteins of all known human coronaviruses (HCoV). Results Significantly higher prevalence of SARS-CoV-2 serological cross-reactivity was detected in samples from SSA compared to USA. Majority of these cross-reactive samples cross-recognized SARS-CoV-2 nucleocapsid protein together with recognition of spike proteins from other HCoVs. Since nucleocapsid proteins from HCoV-NL63 and HCoV-229E were detected by majority of samples, it implicates prior exposure to these two HCoVs as the likely source for cross-reactive antibodies against SARS-CoV-2. Conclusion Low SARS-CoV-2 infection and disease in SSA appears to correlate with pre-pandemic serological cross-recognition of HCoVs, which are substantially more prevalent in SSA than USA.