In July 2020, we commenced a community COVID-19 seroprevalence study at existing clinical trials sites in Mali. This study is a Public Health Surveillance Activity in collaboration with the Ministry of Health in Mali to describe the sero-epidemiology of COVID-19 in urban and rural populations. Using the demographic and clinical information collected from participants, we will describe the age-stratified seroprevalence and fraction of asymptomatic/pauci-symptomatic cases to help understand the penetration of SARS-CoV-2 into the community. Additional exploratory objectives to understand viral carriage, locally circulating variants, and improve direct virus detection at study sites have been added to help enhance local capacity for Public Health surveillance and possible future clinical trials. Separately, we have leveraged our in-house vaccine platforms to develop COVID-19 vaccine candidates that may be suitable for use in low/middle income countries like Mali. From our publications this year, we report the following advances in FY2022: Woodford J, Sagara I, Diawara H, Assadou M, Katile A, Attaher O, Issiaka D, Santara G Soumbounou I, Traore S, Traore M, Dicko O, Niambele S, Mahamar A, Kamate B, Haidara B, Sissoko K, Sankare S, Diarra S, Zeguime A, Doritchamou J, Zaidi I, Dicko A, Duffy PE. Recent malaria does not substantially impact COVID-19 antibody response or rates of symptomatic illness in communities with high malaria and COVID-19 transmission in Mali, West Africa. 2022. Frontiers in Immunology. Aug 3. Malaria has been hypothesized as a factor that may have reduced the severity of the COVID-19 pandemic in sub-Saharan Africa. To evaluate the effect of recent malaria on COVID-19, we assessed a subgroup of individuals participating in a longitudinal cohort COVID-19 serosurvey that were also undergoing intensive malaria monitoring as part of antimalarial vaccine trials during the 2020 transmission season in Mali. These communities experienced a high incidence of primarily asymptomatic or mild COVID-19 during 2020 and 2021. In 1314 individuals, 711 had intercurrent parasitemia; 442 were symptomatic with clinical malaria and 269 had asymptomatic parasitemia. Intercurrent parasitemia was not associated with new COVID-19 seroconversion (29.7% (211/711) vs. 30.0% (181/603), p=0.9038) or with rates of reported symptomatic seroconversion during the malaria transmission season. In the subsequent dry season, prior parasitemia was not associated with new COVID-19 seroconversion (22.0% (133/605) vs. 22.1% (108/488), p>0.9999), with symptomatic seroconversion, or with reversion from seropositive to seronegative (prior parasitemia: 36.2% (64/177) vs. no parasitemia: 30.1% (37/119), p=0.3842). After excluding participants with asymptomatic parasitemia, clinical malaria was also not associated with COVID-19 serostatus or symptomatic seroconversion when compared to participants with no parasitemia during the monitoring period. In communities with intense seasonal malaria and a high incidence of asymptomatic or mild COVID-19, we did not demonstrate a relationship between recent malaria and subsequent response to COVID-19. Lifetime exposure, rather than recent infection, may be responsible for any effect of malaria on COVID-19 severity. Woodford J, Sagara I, Kwan JL, Zaidi I, Dicko A, Duffy PE. Assessing and minimizing the effect of malaria on SARS-CoV-2 serodiagnostics. 2021. Frontiers in Tropical Diseases. Dec 13. Malaria may affect the reliability of SARS-CoV-2 seroassay performance and limit understanding of SARS-CoV-2 epidemiology in malaria-endemic regions. We presented our experience conducting SARS-CoV-2 serosurveillance in seasonal malaria-affected communities in Mali and discuss relevant literature regarding the effect of malaria on the performance of SARS-CoV-2 serodiagnostics, including approaches to minimize the effect of malaria-associated assay interference. Woodford J, Sagara I, Dicko A, Zeguime A, Doucoure M, Kwan J, Zaidi I, Doritchamou JYA, Snow-Smith M, Alani N, Renn JP, Kosik I, Holly J, Yewdell J, Esposito D, Sadtler K, Duffy PE. SARS-CoV-2 seroassay performance and optimization in a population with high background reactivity in Mali. 2021. Journal of Infectious Diseases. Oct 6. False positivity may hinder the utility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests in sub-Saharan Africa. From 312 Malian samples collected before 2020, we measured antibodies to the commonly tested SARS-CoV-2 antigens and 4 other betacoronaviruses by enzyme-linked immunosorbent assay (ELISA). In a subset of samples, we assessed antibodies to a panel of P. falciparum antigens by suspension bead array and functional antiviral activity by SARS-CoV-2 pseudovirus neutralization assay. We then evaluated the performance of an ELISA using SARS-CoV-2 spike protein and receptor-binding domain developed in the United States using Malian positive and negative control samples. To optimize test performance, we compared single- and 2-antigen approaches using existing assay cutoffs and population-specific cutoffs. Background reactivity to SARS-CoV-2 antigens was common in prepandemic Malian samples. The SARS-CoV-2 reactivity varied between communities, increased with age, and correlated negligibly/weakly with other betacoronavirus and P. falciparum antibodies. No pre-pandemic samples demonstrated functional activity. Regardless of the cutoffs applied, test specificity improved using a 2-antigen approach. Test performance was optimal using a 2-antigen assay with population-specific cutoffs (sensitivity, 73.9% 95% confidence interval CI, 51.6-89.8; specificity, 99.4% 95% CI, 97.7-99.9). We have addressed the problem of SARS-CoV-2 seroassay performance in Africa by using a 2-antigen assay with cutoffs defined by performance in the target population. Manning J, Zaidi I, Lon C, Rosas LA, Park JK, Ponce A, Bohl J, Chea S, Karkanitsa M, Sreng S, Rekol H, Chour CM, Esposito D, Taubenberger JK, Memoli MJ, Sadtler K, Duffy PE, Oliveira F. Pre-pandemic SARS-CoV-2 serological reactivity in rural malaria-experienced Cambodians. 2022. Emerging Infectious Diseases. Feb 1. Greater Mekong inhabitants are exposed to pathogens, zoonotic and otherwise, that may influence SARS-CoV-2 seroreactivity. A pre-pandemic (2005 to 2011) serosurvey of from 528 malaria-experienced Cambodians demonstrated higher-than-expected (up to 13.8 %) positivity of non-neutralizing IgG to SARS-CoV-2 spike and RBD antigens. These findings have implications for interpreting large-scale serosurveys. Scaria PV, Rowe CG, Chen BB, Dickey TH, Renn JP, Lambert LE, Barnafo EK, Rausch KM, Tolia NH, Duffy PE. Protein-protein conjugation enhances the immunogenicity of SARS-CoV-2 receptor-binding domain (RBD) vaccines. iScience. 2022 Aug 19;25(8):104739. doi: 10.1016/j.isci.2022.104739. Epub 2022 Jul 9. PMID: 35846379; PMCID: PMC9270177. Receptor binding domain of the SARS-CoV-2 Spike protein was conjugated to a carrier protein. This conjugate has demonstrated significantly higher immunogenicity compared to unconjugated antigen and the immune sera showed high levels of virus neutralizing functional activity against different variants of the SARS-CoV-2 virus. Further studies of this conjugate in non-human primate are ongoing. We also have initiated plan to develop Omicron specific vaccine candidate using this vaccine technology.