High prevalence of pre-existing serological cross-reactivity against SARS-CoV-2 in sub-Sahara Africa

Tso, For Yue; Lidenge, Salum J.; Peña, Phoebe B.; Clegg, Ashley A.; Ngowi, John R.; Mwaiselage, Julius; Ngalamika, Owen; Julius, Peter; West, John T.; Wood, Charles

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.