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Preprint in English | EuropePMC | ID: ppcovidwho-291656


Background: Raising immunization coverage against COVID-19, in particular in low- and middle-income countries (LMICs), is crucial in addressing the current pandemic. Additionally, in Africa reaching the necessary herd immunity threshold is jeopardized by factors, such as vaccine hesitancy. To build confidence in COVID-19 vaccines, it is important to understand and address the reasons for vaccine hesitancy. Yet, few studies for rural and urban Sub-Saharan Africa exist, which have analyzed these factors. Methods: This study reports on a cross-sectional survey in five West African countries (Burkina Faso, Guinea, Mali, Senegal, and Sierra Leone) to identify and describe factors influencing COVID-19 vaccine hesitancy in rural and urban settings. The survey was conducted at a time when in these countries the roll-out of COVID-19 vaccines had not yet or only just begun. Data were analyzed using descriptive statistics and Poisson regression models, with robust standard errors. The general protocol is registered on (protocol number: NCT04912284) Results: Findings show that in West Africa COVID-19 adult vaccine acceptance ranges from 60% in Guinea and 50% in Sierra Leone to 11% in Senegal. This is largely congruent with acceptance levels of COVID-19 vaccinations for children. Multivariable regression analysis shows that perceived effectiveness and safety of COVID-19 vaccines increased the willingness to get vaccinated, rather than socio-demographic factors, such as educational attainment and rural/urban residence. Primary sources of information about COVID-19 vaccines, include television, radio, and social media. Conclusions: Communication strategies addressed at the adult population using mass and social media, which emphasize COVID-19 vaccine effectiveness and safety, could encourage greater acceptance also of COVID-19 child vaccinations in Sub-Saharan countries.

BMC Med Res Methodol ; 21(1): 165, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1352645


BACKGROUND: A considerable proportion of SARS-CoV-2 transmission occurs from asymptomatic and pre-symptomatic cases. Therefore, different polymerase chain reaction (PCR)- or rapid antigen test (RAT)-based approaches are being discussed and applied to identify infectious individuals that would have otherwise gone undetected. In this article, we provide a framework to estimate the time-dependent risk of being infectious after a negative SARS-CoV-2 test, and we simulate the number of expected infectious individuals over time in populations who initially tested negative. METHODS: A Monte Carlo approach is used to simulate asymptomatic infections over a 10-days period in populations of 1000 individuals following a negative SARS-CoV-2 test. Parameters representing the application of PCR tests or RATs are utilized, and SARS-CoV-2 cumulative 7-day incidences between 25 and 200 per 100,000 people are considered. Simulation results are compared to case numbers predicted via a mathematical equation. RESULTS: The simulations showed a continuous increase in infectious individuals over time in populations of individuals who initially tested SARS-CoV-2 negative. The interplay between false negative rates of PCR tests or RATs, and the time that has passed since testing determines the number of infectious individuals. The simulated and the mathematically predicted number of infectious individuals were comparable. However, Monte Carlo simulations highlight that, due to random variation, theoretically observed infectious individuals can considerably exceed predicted case numbers even shortly after a test was conducted. CONCLUSIONS: This study demonstrates that the number of infectious individuals in a screened group of asymptomatic people can be effectively reduced, and this effect can be described mathematically. However, the false negative rate of a test, the time since the negative test and the underlying SARS-CoV-2 incidence are critical parameters in determining the observed subsequent number of cases in tested population groups.

COVID-19 , Communicable Diseases , Computer Simulation , Humans , Polymerase Chain Reaction , SARS-CoV-2
Trop Med Int Health ; 26(6): 621-631, 2021 06.
Article in English | MEDLINE | ID: covidwho-1119265


OBJECTIVES: Specific serological tests are mandatory for reliable SARS-CoV-2 diagnostics and seroprevalence studies. Here, we assess the specificities of four commercially available SARS-CoV-2 IgG ELISAs in serum/plasma panels originating from Africa, South America, and Europe. METHODS: 882 serum/plasma samples collected from symptom-free donors before the COVID-19 pandemic in three African countries (Ghana, Madagascar, Nigeria), Colombia, and Germany were analysed with three nucleocapsid-based ELISAs (Euroimmun Anti-SARS-CoV-2-NCP IgG, EDI™ Novel Coronavirus COVID-19 IgG, Mikrogen recomWell SARS-CoV-2 IgG), one spike/S1-based ELISA (Euroimmun Anti-SARS-CoV-2 IgG), and in-house common cold CoV ELISAs. RESULTS: High specificity was confirmed for all SARS-CoV-2 IgG ELISAs for Madagascan (93.4-99.4%), Colombian (97.8-100.0%), and German (95.9-100.0%) samples. In contrast, specificity was much lower for the Ghanaian and Nigerian serum panels (Ghana: NCP-based assays 77.7-89.7%, spike/S1-based assay 94.3%; Nigeria: NCP-based assays 39.3-82.7%, spike/S1-based assay 90.7%). 15 of 600 African sera were concordantly classified as positive in both the NCP-based and the spike/S1-based Euroimmun ELISA, but did not inhibit spike/ACE2 binding in a surrogate virus neutralisation test. IgG antibodies elicited by previous infections with common cold CoVs were found in all sample panels, including those from Madagascar, Colombia, and Germany and thus do not inevitably hamper assay specificity. Nevertheless, high levels of IgG antibodies interacting with OC43 NCP were found in all 15 SARS-CoV-2 NCP/spike/S1 ELISA positive sera. CONCLUSIONS: Depending on the chosen antigen and assay protocol, SARS-CoV-2 IgG ELISA specificity may be significantly reduced in certain populations probably due to interference of immune responses to endemic pathogens like other viruses or parasites.

Antibodies, Viral/blood , COVID-19/diagnosis , Enzyme-Linked Immunosorbent Assay/methods , Immunoglobulin G/blood , Adolescent , Adult , COVID-19/virology , Child , Child, Preschool , Colombia , Coronavirus Nucleocapsid Proteins/immunology , Female , Germany , Ghana , Humans , Madagascar , Male , Middle Aged , Nigeria , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology , Young Adult