Obstacles au don bénévole de sang dans la population de Kisangani en République Démocratique du Congo

Introduction: Plusieurs facteurs font obstacles au don de sang dans les pays en développement. La  présente étude avait pour objectifs d'analyser les connaissances, attitudes et pratiques de la population  de Kisangani relatives au don de sang et d'identifier les obstacles au don de sang afin de guider la planification des activités de promotion du don de sang. Méthodes: L' enquête a été réalisée du 4 février au 27 août 2008 sur un échantillon de 1067 sujets par entretien. Résultats: Sur 1067 sujets interviewés, 1002 (93.9%) sujets ont accepté de répondre. La plupart de nos enquêtés (81.5%, n=1002) avait connaissance de la pratique du don bénévole de sang à Kisangani.  Quoique la majorité des sujets approuvent la pratique du don de sang, 57.9 % (n=416) parmi eux n'ont  jamais fait un don de sang. La raison principale avancé par ceux qui n'ont jamais fait un don de sang était  qu'ils n'avaient pas été sollicités tandis que 35 % (n=144), quoique sollicités, avaient refusés de faire un  don de sang pour diverses raisons.Conclusion: Cette enquête met en lumière le fait qu'il y a maintenant dans la population de Kisangani une attitude favorable au don de sang. Mais plusieurs obstacles empêchent encore le passage à l'acte. Des activités de promotion qui s'appuient sur la communication interpersonnelle devraient être mises sur  pieds afin de passer des messages personnalisés aux donneurs potentiels de sang.Key words: Transfusion, don de sang, Connaissance, attitudes, pratiques, République Démocratique du Cong

Prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang à Kisangani, République Démocratique du Congo

Introduction: Le paludisme transfusionnel est une réalité en Afrique Sub-saharienne, en raison des  transfusions sanguines répétées, peu ou non contrôlées et où les donneurs sont en majorité  potentiellement porteurs d'hématozoaires. L'objectif de cette étude était de déterminer la prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang à Kisangani.Méthodes: Une étude transversale a été menée au Centre Provincial de Transfusion Sanguine à  Kisangani  du 1er Décembre 2012 au 31 Mars 2013 et a concerné 480 donneurs bénévoles de sang.Résultats: La prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang était de 28,3%. Plasmodium falciparum était l'espèce la plus répandue (96,3%). Près de la moitié des donneurs avait une parasitémie supérieure à 2000 parasites/μl. Les facteurs qui étaient  significativement associés à la parasitémie étaient le jeune âge, le 1er don, et la non utilisation de lamoustiquaire imprégnée d'insecticide à longue durée (MILD).Conclusion: Les résultats de cette étude montrent que la prévalence du portage asymptomatique du plasmodium chez les donneurs bénévoles de sang était élevée, constituant ainsi un risque important de transmission du parasite aux receveurs  souvent en mauvais état général. Cependant, l'utilisation de la MILD et la fidélisation des donneurs  bénévoles semblent constituer des moyens utiles de réduction du risque de portage asymptomatique du Plasmodium. Une sensibilisation et éventuellement des  distributions ciblées de MILD aux donneurs, en particuliers les plus jeunes, pourraient réduire  considérablement le portage du Plasmodium parmi les donneurs de sang et ainsi réduire le risque de paludisme transfusionnel.Key words: Paludisme, Prévalence parasitaire, Donneur bénévole de sang, Transfusion sanguine, République Démocratique du Congo

Seroprevalence of hepatitis B and C virus infections among diabetic patients in Kisangani (North-eastern Democratic Republic of Congo)

Introduction: the link between diabetes mellitus and hepatitis B and C Virus infections has not yet been studied in the Democratic Republic of Congo, a country where diabetes mellitus is a growing disease and the prevalence of hepatitis B and C viruses infections is high. The aim of this study was to determine the seroprevalence of these viruses in diabetic patients. Methods: we conducted a descriptive cross-sectional study in diabetic subjects attending Kisangani University Clinics and General Hospitals of Kisangani City as well as the Diabetics Association of Oriental Province. The control group consisted of volunteer blood donors recruited from the Kisangani Provincial Blood Transfusion Center. Blood glucose was measured with the spectrophotometer; for hepatitis B and hepatitis C viruses serology, we used rapid test kits (Determine TM® HBsAg and Hexagon® HCV test) and ELISA if seropositivity by rapid tests. The analysis was done by SPSS software. Results: seroprevalence of hepatitis C virus in diabetics was 24.8% compared to 1.9% in volunteer blood donors (p = 0.0000); that of hepatitis B virus was 3.4% versus 3.5% in volunteer blood donors (p = 0.906). Hepatitis C virus infection was more common in type 2 diabetics (p = 0.006) and significantly associated with age of diabetic patients (p = 0.002). Conclusion: the seroprevalence of hepatitis C virus and not hepatitis B virus infection is significantly high in diabetic subjects, particularly type 2 diabetics, in the Democratic Republic of Congo and suggests systematic screening for this infection in any diabetic patient

Auto-test sur sang prélevé au bout du doigt pour la détection d'HIV, HBV et HCV utilisant un test immunochromatographique multiplex: étude pilote en Afrique subsaharienne

peer reviewedBACKGROUND: The burden of HIV, HBV, and HCV infections remains disproportionately high in sub-Saharan Africa, with high rates of co-infections. Multiplex rapid diagnostic tests for HIV, HBV and HCV serological testing with high analytical performances may improve the "cascade of screening" and quite possibly the linkage-to-care with reduced cost. Based on our previous field experience of HIV self-testing, we herein aimed at evaluating the practicability and acceptability of a prototype finger-stick whole-blood Triplex HIV/HCV/HBsAg self-test as a simultaneous serological screening tool for HIV, HBV, and HCV in the Democratic Republic of the Congo (DRC). METHODS: A cross-sectional multicentric study consisting of face-to-face, paper-based, and semi-structured questionnaires with a home-based and facility-based recruitment of untrained adult volunteers at risk of HIV, HBV, and HCV infections recruited from the general public was conducted in 2020 in urban and rural areas in the DRC. The practicability of the Triplex self-test was assessed by 3 substudies on the observation of self-test manipulation including the understanding of the instructions for use (IFU), on the interpretation of Triplex self-test results and on its acceptability. RESULTS: A total of 251 volunteers (mean age, 28 years; range, 18-49; 154 males) were included, from urban [160 (63.7%)] and rural [91 (36.3%)] areas. Overall, 242 (96.4%) participants performed the Triplex self-test and succeeded in obtaining a valid test result with an overall usability index of 89.2%. The correct use of the Triplex self-test was higher in urban areas than rural areas (51.2% versus 16.5%; aOR: 6.9). The use of video IFU in addition to paper-based IFU increased the correct manipulation and interpretation of the Triplex self-test. A total of 197 (78.5%) participants correctly interpreted the Triplex self-test results, whereas 54 (21.5%) misinterpreted their results, mainly the positive test results harboring low-intensity band (30/251; 12.0%), and preferentially the HBsAg band (12/44; 27.3%). The rates of acceptability of reuse, distribution of the Triplex self-test to third parties (partner, friend, or family member), linkage to the health care facility for confirmation of results and treatment, and confidence in the self-test results were very high, especially among participants from urban areas. CONCLUSIONS: This pilot study shows evidence for the first time in sub-Saharan Africa on good practicability and high acceptability of a prototype Triplex HIV/HCV/HBsAg self-test for simultaneous diagnosis of three highly prevalent chronic viral infections, providing the rational basis of using self-test harboring four bands of interest, i.e. the control, HIV, HCV, and HBsAg bands. The relatively frequent misinterpretation of the Triplex self-test points however the necessity to improve the delivery of this prototype Triplex self-test probably in a supervised setting. Finally, these observations lay the foundations for the potential large-scale use of the Triplex self-test in populations living in sub-Saharan Africa at high risk for HIV, HBV, and HCV infections

Does glucose-6-phosphate dehydrogenase deficiency worsen the clinical features of sickle cell disease? A multi-hospital-based cross-sectional study.

peer reviewed[en] BACKGROUND: The impact of glucose-6-phosphate dehydrogenase deficiency(G-6-PD) on the clinical course of sickle cell disease(SCD) is still controversial. The objectives of this study were to determine the prevalence of G-6-PD deficiency in patients with SCD and its effect on their clinical course. METHODS: A cross-sectional study of 122 SCD patients and 211 healthy blood donors was conducted in Kisangani city. Data were collected through clinical examination supplemented by patient medical records, and laboratory tests based on a survey form. G-6-PD activity was measured by spectrophotometry and the screening for SCD by the HemoTypeSC® rapid test. Statistical analysis was done using SPSS ver. 20.0. RESULTS: The prevalence of G-6-PD deficiency did not differ between SCD and non-SCD subjects, 35.2% vs. 33.6% respectively(p = .767). When comparing the hemoglobin level between SCD patients with and without G-6-PD deficiency, no significant difference was observed. However, in the 6 months prior to the study, SCD patients with G-6-PD deficiency had on average more transfusions than non-deficient SCD patients, 0.64 ± 0.897 vs. 0.24 ± 0.486(p = .004). Similarly, considering the clinical events of the last 12 months prior to the study, there were more hospitalizations, major vaso-occlusive crises and anemia requiring blood transfusion among G-6-PD deficient SCD patients compared to no-deficient, respectively 1.42 ± 1.451vs. 0.76 ± 1.112(p = .007); 1.37 ± 1.092 vs. 0.85 ± 1.014(p = .005); 0.74 ± 0.902 vs. 0.38 ± 0.739 (p = .007). CONCLUSION: The prevalence of G-6-PD deficiency in SCD patients was high but did not differ from that observed in controls. In addition, G-6-PD deficiency appeared to worsen the clinical features of SCD. Nevertheless, prospective studies further clarifying this observation are needed

Renal Abnormalities among Sickle Cell Disease Patients in a Poor Management Setting: A Survey in the Democratic Republic of the Congo.

peer reviewed[en] Background and objective: Sickle cell disease (SCD) is now a well-established cause of renal damage. In the northeast of the Democratic Republic of Congo (DRC), SCD is common. However, sickle cell nephropathy remains unstudied in this region. Thus, this study aimed to assess renal abnormalities in SCD patients in Kisangani (northeastern DRC). Methods: This cross-sectional study included 98 sickle cell patients selected from six health facilities in Kisangani and 89 healthy non-sickle cell subjects as the control group. Based on a survey form, a clinical examination and biological tests were performed to collect data related to the sex, age, weight, height, pressure, serum creatinine, serum uric acid, urinary albumin/creatinine ratio, and hemoglobin phenotype. We used a spectrophotometer to measure serum creatinine and uricemia, the sickle SCAN® device for hemoglobin phenotype, and an automatic multifunction analyzer for urine albumin/creatinine ratio. Data were entered into an Excel file and analyzed on SPSS 20.0. Results: The mean urine albumin-to-creatinine ratio was 11.79±9.03 mg/mmol in SCD patients, significantly higher than in AA (1.69±1.89 mg/mmol) and AS (2.97±4.46 mg/mmol) subjects. The decrease in glomerular filtration rate was more observed in SCD patients with hyperuricemia compared to those with normal uric acid levels. A significantly elevated prevalence of chronic kidney disease was observed among SCD patients (87.8%) compared to 23.8% in AS and 7.7% in AA subjects. Conclusions: This study highlighted that albuminuria and chronic kidney disease are common in SCD patients in Kisangani. More studies are needed to further document these complications

Drépanocytose et transfusion sanguine: étude réalisée à Kisangani en République Démocratique du Congo

IntroductionLa drépanocytose, affection génétique concernant 1 à 2% de la population en Afrique sub-saharienne, est une maladie chronique dont l’un des traitements essentiels est la transfusion sanguine. Kisangani, une ville du Nord-est de la République Démocratique du Congo, compte environ un million d’habitants et près de 30 000 naissances par an. Elle est caractérisée entre autre par l’endémie malarienne, la fréquence élevée dans la population des virus de l’immunodéficience humaine (VIH), des virus des hépatites B (VHB) et C (VHC) et la carence d’autosuffisance en sang. Le don de sang est fait par des donneurs volontaires et par des donneurs de remplacement. Les tests VIH et VHB sont réalisés chez les donneurs depuis les années 80, celui de VHC depuis fin 2004. Dans ce contexte, définir des actions prioritaires pour assurer, en général et en particulier pour les patients drépanocytaires, la sécurité transfusionnelle la plus optimale possible est essentiel. MéthodologieAfin de déterminer les prévalences d’infections virales, les marqueurs sérologiques du VIH, VHB et VHC ont été recherchés chez 4637 donneurs de sang (2236 volontaires et 2401 de remplacement) du Centre Provincial de Transfusion et des hôpitaux de Kisangani. Chez 140 patients drépanocytaires suivis dans un centre médical de Kisangani, 127 ont été transfusés. Parmi eux, 79 sont « polytransfusés » et 94 ont été transfusés avant 2004. Outre la sérologie VIH, VHB et VHC, l’allo-immunisation anti-HLA et anti-érythrocytaire ont été recherchées et les indications de transfusion déterminées. Afin d’estimer la prévalence de la drépanocytose à la naissance, l’HbS a été identifiée systématiquement par focalisation isoélectrique sur du sang du cordon ombilical de 520 nouveau-nés suivis dans cinq maternités de Kisangani. Afin de déterminer les indications transfusionnelles dans la drépanocytose à Kisangani, un relevé de ces indications a été réalisé pour ces mêmes 127 patients drépanocytaires transfusés. Afin de comparer l’usage de la transfusion à Kisangani et à Bruxelles pour des complications non liées à l’environnement, les 140 patients drépanocytaires suivis à Kisangani ont été comparés à 195 patients suivis à Bruxelles ;parmi eux, 71 patients ont pu être appariés pour l’âge. RésultatsLa prévalence des marqueurs viraux chez les donneurs de sang est de l’ordre de 4% pour le VIH, de 5% pour le VHB et de 4% pour le VHC. Les séroprévalences de VIH (2,2 vs 4,1%) et VHB (3,0 vs 4,6%) sont moindres chez les donneurs bénévoles par rapport aux donneurs de remplacement. La prévalence du VIH et du VHB observée chez les donneurs bénévoles était plus élevée en 2006 qu’en 2004. Treize patients drépanocytaires non transfusés ne sont pas porteurs des marqueurs viraux. Six pourcent des patients qui ont une sérologie VHC positive sont des polytransfusés ;1% chez ceux qui avaient reçu une ou deux transfusions. Suite au retard d’introduction du dépistage VHC chez les donneurs, une séroprévalence pour le VHC de 7 % des malades pour seulement 0,7% pour celle du VIH et de 1,4% pour celle du VHB a été démontrée. Le fait qu’aucun patient transfusé après 2004, n’a été trouvé positif au VHC alors que 10 % l’ont été parmi ceux transfusés avant 2004 montre le bénéfice de l’introduction de moyens simples et peu coûteux. Deux (1,6 %) patients étaient porteurs d’anticorps anti-HLA et 13 (10%) des anticorps anti-érythrocytaires (2 anti-C-D, 1 anti-E et 1 anti-C-D-E). Aucun des patients n’étaient porteurs des anticorps anti-Kell (K), anti-Kidd (Jka et Jkb) ou anti-Duffy. La prévalence de la drépanocytose chez les nouveau-nés de Kisangani est d’environ 1 %. A Kisangani, outre l’anémie liée à la malaria (46 %), un facteur environnemental, 34 % des transfusions ont été administrées pour des crises douloureuses simples. En comparaison, aucun patient suivi à Bruxelles n’a été transfusé pour cette indication. Cette attitude est probablement à mettre en relation avec la méconnaissance de la maladie par le personnel médical et par les familles des malades. L’anémie chronique de ces patients est souvent mal connue et interprétée comme une anémie aiguë. ConclusionUn encouragement des dons bénévoles sans exclure les donneurs de remplacement est nécessaire pour continuer à accroître l’approvisionnement en sang. Afin d’améliorer la sécurité transfusionnelle, la généralisation des tests simples de dépistage des donneurs de sang comme ceux du VHC devrait constituer une priorité dans les centres de transfusion. Avec une prévalence d’environ 1%, la drépanocytose est une affection fréquente à Kisangani. Pour ces patients drépanocytaires, établir des recommandations concernant les indications transfusionnelles permettrait de leur éviter des transfusions inappropriées. AbstractIntroduction Sickle cell disease (SCD), a genetic disorder that affects 1% to 2% of the population in sub-Saharan Africa, is a chronic disease in which blood transfusion is one of the essential treatments. Kisangani, a town in north-eastern Democratic Republic of Congo, has about one million inhabitants and nearly 30 000 births per year. It is characterized among others by the endemic malarial, a high frequency in the population of human immunodeficiency virus (HIV), hepatitis B (HBV) and C (HCV) virus, but also a lack of self-sufficiency in blood. Blood donation is given by volunteers and replacement donors. HBV and HIV screening tests are performed in donors since the 80s, while for HCV it is available only since late 2004. In that context in view to ensure blood transfusion safety, it is essential to define priority actions, in general and especially for patients with sickle cell disease.Methodology To determine the prevalence of viral infections, serological markers for HIV, HBV and HCV were investigated in 4637 blood donors (2236 volunteers and 2401 replacement) of the Provincial Center of Transfusion and hospitals in Kisangani. Among 140 SCD-patients followed in a medical centre in Kisangani, 127 were transfused; 79 were considered as “multiple-transfused” and 94 were transfused before 2004. HIV, HBV and HCV seroprevalences, alloimmunization anti-HLA and against red blood cells were determined as well as the indications for transfusion. To estimate the prevalence of SCD at birth, HbS was identified by isoelectric focusing on umbilical cord blood of 520 newborns in five maternities of Kisangani.To determine the indications for transfusion in SCD patients at Kisangani, these indications were recorded for the 127 SCD transfused patients.To compare the use of transfusion in Kisangani and in Brussels for clinical events unrelated to the environment, the 140 SCD-patients followed in Kisangani were compared with the 195 SCD-patients followed in Brussels and 71 patientsin both groups could be matched for age. Results The prevalence of viral markers among blood donors is around 4% for HIV, 5% for HBV and 4% for HCV. The seroprevalence of HIV (2.2 vs. 4.1%) and HBV (3.0 vs. 4.6%) were lower among volunteer donors compared to replacement donors. The prevalence of HIV and HBV infection observed among blood donors was higher in 2006 than in 2004.Thirteen non-transfused sickle cell patients were not carriers of any serological viral marker. The SCD-patients HCV(+) were “multiple-transfused” patients (6%) or those who received one or two transfusions (1%). Following the delayed introduction of HCV donor screening, a HCV seroprevalence of 7% of patients for only 0.7% for the HIV and 1.4% for the HBV was demonstrated. The fact that no patients transfused after 2004 were HCV(+) compared to 10% of those transfused before 2004 shows the benefit of the introduction of a simple and inexpensive screening test. Two (1.6%) patients had anti-HLA antibodies and 13 (10%) red blood cells antibodies (2 anti-CD, 1 anti-E and an anti-C-D-E). None of the patients displayed Kell (K), Kidd (Jka and Jkb) or Duffy red cells antibodies.The prevalence of sickle cell disease in newborns of Kisangani is about 1%. In Kisangani, in addition to anaemia due to malaria (46%), an environmental factor, 34% of transfusions were administered for uncomplicated painful crises. In comparison, no patient followed in Brussels were transfused for that indication. This attitude is likely to be related with the ignorance of the disease by the medical staff and patients’ families. The chronic anaemia of those patients is often poorly understood and interpreted as acute anaemia.ConclusionEncouragement of voluntary donations without excluding the replacement donors is needed to pursue to increase the blood supply. To improve blood safety, the generalization of simple tests for screening blood donors as those for HCV should be a priority in transfusion centres. With a prevalence of about 1%, the SCD is a common disease in Kisangani. For those SCD-patients, establish guidelines for indications of transfusion would avoid inappropriate transfusion.Doctorat en Sciences médicalesinfo:eu-repo/semantics/nonPublishe

Adverse reactions in voluntary whole blood donors: Experience at the National Blood Transfusion Centre in Democratic Republic of Congo

Background: Whole blood donation, generally considered as a safe procedure, may be sometimes associated with adverse reactions and injuries of variable severity during or after the blood donation process. There are few reports of adverse events related to blood donation in the Democratic Republic of Congo.Objectives: The aim of this study was to document the frequencies and types of adverse reactions in whole blood donors.Materials and methods: A prospective study was conducted and data collected from January 2006 to December 2012 at the National Blood Transfusion Centre in Kinshasa, Democratic Republic of Congo. In this centre, all blood donors are voluntary and blood donation is only of whole blood. All donor events and complications were recorded in the consecutive 150696 whole blood donations at the centre and were later analyzed.Results: Overall 2717 (1.8%) of the 150696 donors showed adverse reactions. Vasovagal reactions (dizziness, intense thirst, nausea, sweating, palpitations, vomiting, blurred vision and loss of consciousness) accounted for 84.3%, and local reactions (haematoma, contact allergy, etc) for 15.7% of all adverse reactions. 71.0% of adverse reactions observed, were in first-time blood donors.Conclusion: Analysis of adverse reactions related to blood donation is necessary in order to design appropriate voluntary donor motivational strategies, and to improve pre-donation counseling, and donor care during, and after blood donation. Blood centres have an obligation to assure blood donor safety by constant effort to minimise blood donation complications, so as to promote voluntary blood donation.Keywords: Blood donation, adverse reactions, vasovagal reaction, needle-related complication

Capillary whole-blood IgG-IgM COVID-19 selftest as a serological screening tool for SARSCoV-2 infection adapted to the general public

The practicability of a prototype capillary whole-blood IgG-IgM COVID-19 self-test (Exacto® COVID-19 self-test, Biosynex Swiss SA, Freiburg, Switzerland) as a serological screening tool for SARS-CoV-2 infection adapted to the general public was evaluated in across-sectional, general adult population study performed between April and May 2020 in Strasbourg, France, consisting of face-to-face, paper-based, semi-structured, and selfadministrated questionnaires. Practicability was defined as the correct use of the self-test and the correct interpretation of the result. The correct use of self-test was conditioned by the presence of the control band after 15-min of migration. The correct interpretation of the tests was defined by the percent agreement between the tests results read and interpret by the participants compared to the expected results coded by the numbers and verified by trained observers. A total of 167 participants (52.7% female; median age, 35.8 years; 82% with post-graduate level) were enrolled, including 83 and 84 for usability and test results interpretation substudies, respectively. All participants (100%; 95% CI: 95.6– 100) correctly used the self-test. However, 12 (14.5%; 95% CI: 8.5–23.6) asked for verbal help. The percent agreement between the tests results read and interpret by the participants compared to the expected results was 98.5% (95% CI: 96.5–99.4). However, misinterpretation occurred in only 2.3% of positive and 1.2% of invalid test results. Finally, all (100%) participants found that performing the COVID-19 self-test was easy; and 98.8% found the interpretation of the self-test results easy. Taken together, these pilot observations demonstrated for the first-time, high practicability and satisfaction of COVID-19 selftesting for serological IgG and IgM immune status, indicating its potential for use by the general public to complete the arsenal of available SARS-CoV-2 serological assays in the urgent context of the COVID-19 epidemic

Evaluation of the Practicability of Biosynex Antigen Self-Test COVID-19 AG+ for the Detection of SARS-CoV-2 Nucleocapsid Protein from Self-Collected Nasal Mid-Turbinate Secretions in the General Public in France

Due to their ease-of-use, lateral flow assay SARS-CoV-2 antigen-detecting rapid diagnostic tests could be suitable candidates for antigen-detecting rapid diagnostic self-test (Ag-RDST). We evaluated the practicability of the Ag-RDST BIOSYNEX Antigen Self-Test COVID-19 Ag+ (Biosynex Swiss SA, Freiburg, Switzerland), using self-collected nasal secretions from the turbinate medium (NMT), in 106 prospectively included adult volunteers living in Paris, France. The majority of the participants correctly understood the instructions for use (94.4%; 95% confidence interval (CI): 88.3–97.4), showing a great ability to perform the entire self-test procedure to obtain a valid and interpretable result (100%; 95% CI: 96.5–100), and demonstrated the ability to correctly interpret test results (96.2%; 95% CI: 94.2–97.5) with a high level of general satisfaction. About one in eight participants (# 15%) needed verbal help to perform or interpret the test, and only 3.8% of test results were misinterpreted. By reference to multiplex real-time RT-PCR, the Ag-RDST showed 90.9% and 100% sensitivity and specificity, respectively, and high agreement (98.1%), reliability (0.94), and accuracy (90.9%) to detect SARS-CoV-2 antigen. Taken together, our study demonstrates the high usability and accuracy of BIOSYNEX Antigen Self-Test COVID-19 Ag+ for supervised self-collected NMT sampling in an unselected adult population living in France