Seroprevalence of SARS-CoV-2 antibodies in Malawi blood donors

Type of study: Cross-sectional observation study. Problem: In low-income countries, such as Malawi, important public health measures including universal face mask use, social distancing or a lockdown, have been challenging to implement owing to socioeconomic constraints, leading to predictions that the COVID-19 pandemic would progress rapidly. However, due to limited capacity to test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, there are no reliable estimates of the true burden of infection and death. SARS-CoV-2 serosurveys of blood donor samples in blood banks are supported by WHO as a potential useful tool for tracking the emergence and progression of the COVID-19 pandemic. Broad and Specific Objectives: Broad objective: to identify for SARS-CoV-2 antibodies in blood donors in Malawi, as a marker of past infection and an estimate of population exposure. Specific objectives: Primary objective: to estimate the seroprevalence of SARS CoV-2-specific antibodies in blood donor sera of different age-strata across the entire country. Secondary objectives a) to establish when COVID-19 started circulating in Malawi, and b) to determine the COVID-19 epidemic trajectory over time in Malawi Methodology: Repeated cross-sectional investigation of blood donors from across the country. Using the MBTS sample archive database, we will identify sera collected from multiple age groups, including 15-19, 20-29, 30-39, 40-49, 50-59 and 60+. We will conduct two serosurveys using sera collected between December 2019 to May 2020 (Serosurvey 1), and also those to be collected between June 2020 to December 2020 (Serosurvey 2). SARSCoV-2 antibodies will be measured from the sera using ELISA and Luminex-based IgG/IgM multiplex assay targeting Spike (S) and Nucleoprotein (N). We will also measure neutralisation potency of the detected SARS-CoV-2 antibodies. Study setting and period: The laboratory experiments will be conducted at the MLW laboratories. The study will be conducted between October 2020 to July 2021. Ethical considerations: At time of donation, blood donors provide consent to participate in studies of public health importance or those aimed at improving availability of supplies of safe blood. COVID-19 research qualifies for an activity of emergency Public Health importance. We will generate unique sample identifiers and will not have access to the donor details with identifiable names. Data Management and analysis: All data will be stored in secure password protected computers at the MLW. Only study investigators will have access to the data, unless prior collaborative agreements are in place or data has been released as part of open access. We will calculate population and age-specific seroprevalence of SARS CoV-2. These will be reported as proportions of SARS CoV-2 antibody positive individual in the total population or per age strata. We will also estimate the potential period of SARS-CoV-2 entry into Malawi, by using the latest known validated SARS-CoV-2 antibody positive sample. Expected findings: a) Prevalence of SARS CoV-2 exposure amongst blood donors, as a surrogate of population exposure, b) An estimate of potential time of SARS CoV-2 entry into Malawi. Dissemination: The results will be disseminated at local and international conference and manuscripts will be published in an international peer-reviewed journal, and policy-related findings will be shared via the MLW Policy unit. The results will also be shared with COMREC.