Rapid Decision Algorithm for Patient Triage during Ebola Outbreaks.

The low specificity of Ebola virus disease clinical signs increases the risk for nosocomial transmission to patients and healthcare workers during outbreaks. Reducing this risk requires identifying patients with a high likelihood of Ebola virus infection. Analyses of retrospective data from patients suspected of having Ebola virus infection identified 13 strong predictors and time from disease onset as constituents of a prediction score for Ebola virus disease. We also noted 4 highly predictive variables that could distinguish patients at high risk for infection, independent of their scores. External validation of this algorithm on retrospective data revealed the probability of infection continuously increased with the score.

Genomic Microevolution of Vibrio cholerae O1, Lake Tanganyika Basin, Africa.

Africa's Lake Tanganyika basin is a cholera hotspot. During 2001-2020, Vibrio cholerae O1 isolates obtained from the Democratic Republic of the Congo side of the lake belonged to 2 of the 5 clades of the AFR10 sublineage. One clade became predominant after acquiring a parC mutation that decreased susceptibility to ciprofloxacin.

Evaluating lactate prognostic value in children suspected of acetaminophen-induced liver failure in Liberia.

BACKGROUND: The prognostic significance of hyperlactatemia in young children with liver injury suspected to be attributed to repeated supratherapeutic doses of acetaminophen remain understudied. METHODS: We conducted a retrospective medical chart review including children aged <5 years admitted with hepatocellular injury. The study was conducted in Bardnesville Junction Hospital operated by Médecins Sans Frontières in Monrovia, Liberia. RESULTS: We analyzed 95 children with liver injury in whom a blood lactate measurement on admission was available. Eighty children (84%) were aged <2 years; 49 children (52%) died during hospitalization. The median acetaminophen concentration on admission was 20 mg/L with 60 (70%) children presenting concentrations exceeding 10 mg/L. Median lactate was significantly higher in children who died (10.7 mmol/L; interquartile range (IQR): 8.5-15.7) than those who survived (6.1 mmol/L; IQR: 4.1-8.5), P value < 0.001). The optimal threshold obtained was 7.2 mmol/L with a sensitivity of 84% and specificity 70% (area under curve = 0.80). The previously established thresholds of 3.5 and 4 mmol/L lactate had very low specificity identifying non-survival in children included in this study. CONCLUSION: In this setting, young children with ALF possibly attributed to acetaminophen toxicity were unlikely to survive if the venous blood lactate concentration exceeded 7.2 mmol/L.

Correction to: Suspected paracetamol overdose in Monrovia, Liberia: a matched case-control Study.

An amendment to this paper has been published and can be accessed via the original article.

Suspected paracetamol overdose in Monrovia, Liberia: a matched case-control study.

BACKGROUND: A cluster of cases of unexplained multi-organ failure was reported in children at Bardnesville Junction Hospital (BJH), Monrovia, Liberia. Prior to admission, children's caregivers reported antibiotic, antimalarial, paracetamol, and traditional treatment consumption. Since we could not exclude a toxic aetiology, and paracetamol overdose in particular, we implemented prospective syndromic surveillance to better define the clinical characteristics of these children. To investigate risk factors, we performed a case-control study. METHODS: The investigation was conducted in BJH between July 2015 and January 2016. In-hospital syndromic surveillance identified children with at least two of the following symptoms: respiratory distress with normal pulse oximetry while breathing ambient air; altered consciousness; hypoglycaemia; jaundice; and hepatomegaly. After refining the case definition to better reflect potential risk factors for hepatic dysfunction, we selected cases identified from syndromic surveillance for a matched case-control study. Cases were matched with in-hospital and community-based controls by age, sex, month of illness/admission, severity (in-hospital), and proximity of residence (community). RESULTS: Between July and December 2015, 77 case-patients were captured by syndromic surveillance; 68 (88%) were under three years old and 35 (46%) died during hospitalisation. Of these 77, 30 children met our case definition and were matched with 53 hospital and 48 community controls. Paracetamol was the most frequently reported medication taken by the cases and both control groups. The odds of caregivers reporting supra-therapeutic paracetamol consumption prior to admission was higher in cases compared to controls (OR 6.6, 95% CI 2.1-21.3). Plasma paracetamol concentration on day of admission was available for 19 cases and exceeded 10 µg/mL in 10/13 samples collected on day one of admission, and 4/9 (44%) collected on day two. CONCLUSIONS: In a context with limited diagnostic capacity, this study highlights the possibility of supratherapeutic doses of paracetamol as a factor in multi-organ failure in a cohort of children admitted to BJH. In this setting, a careful history of pre-admission paracetamol consumption may alert clinicians to the possibility of overdose, even when confirmatory laboratory analysis is unavailable. Further studies may help define additional toxicological characteristics in such contexts to improve diagnoses.

Micro-Hotspots of Risk in Urban Cholera Epidemics.

Targeted interventions have been delivered to neighbors of cholera cases in major epidemic responses globally despite limited evidence for the impact of such targeting. Using data from urban epidemics in Chad and Democratic Republic of the Congo, we estimate the extent of spatiotemporal zones of increased cholera risk around cases. In both cities, we found zones of increased risk of at least 200 meters during the 5 days immediately after case presentation to a clinic. Risk was highest for those living closest to cases and diminished in time and space similarly across settings. These results provide a rational basis for rapidly delivering targeting interventions.

The potential impact of case-area targeted interventions in response to cholera outbreaks: A modeling study.

BACKGROUND: Cholera prevention and control interventions targeted to neighbors of cholera cases (case-area targeted interventions [CATIs]), including improved water, sanitation, and hygiene, oral cholera vaccine (OCV), and prophylactic antibiotics, may be able to efficiently avert cholera cases and deaths while saving scarce resources during epidemics. Efforts to quickly target interventions to neighbors of cases have been made in recent outbreaks, but little empirical evidence related to the effectiveness, efficiency, or ideal design of this approach exists. Here, we aim to provide practical guidance on how CATIs might be used by exploring key determinants of intervention impact, including the mix of interventions, "ring" size, and timing, in simulated cholera epidemics fit to data from an urban cholera epidemic in Africa. METHODS AND FINDINGS: We developed a micro-simulation model and calibrated it to both the epidemic curve and the small-scale spatiotemporal clustering pattern of case households from a large 2011 cholera outbreak in N'Djamena, Chad (4,352 reported cases over 232 days), and explored the potential impact of CATIs in simulated epidemics. CATIs were implemented with realistic logistical delays after cases presented for care using different combinations of prophylactic antibiotics, OCV, and/or point-of-use water treatment (POUWT) starting at different points during the epidemics and targeting rings of various radii around incident case households. Our findings suggest that CATIs shorten the duration of epidemics and are more resource-efficient than mass campaigns. OCV was predicted to be the most effective single intervention, followed by POUWT and antibiotics. CATIs with OCV started early in an epidemic focusing on a 100-m radius around case households were estimated to shorten epidemics by 68% (IQR 62% to 72%), with an 81% (IQR 69% to 87%) reduction in cases compared to uncontrolled epidemics. These same targeted interventions with OCV led to a 44-fold (IQR 27 to 78) reduction in the number of people needed to target to avert a single case of cholera, compared to mass campaigns in high-cholera-risk neighborhoods. The optimal radius to target around incident case households differed by intervention type, with antibiotics having an optimal radius of 30 m to 45 m compared to 70 m to 100 m for OCV and POUWT. Adding POUWT or antibiotics to OCV provided only marginal impact and efficiency improvements. Starting CATIs early in an epidemic with OCV and POUWT targeting those within 100 m of an incident case household reduced epidemic durations by 70% (IQR 65% to 75%) and the number of cases by 82% (IQR 71% to 88%) compared to uncontrolled epidemics. CATIs used late in epidemics, even after the peak, were estimated to avert relatively few cases but substantially reduced the number of epidemic days (e.g., by 28% [IQR 15% to 45%] for OCV in a 100-m radius). While this study is based on a rigorous, data-driven approach, the relatively high uncertainty about the ways in which POUWT and antibiotic interventions reduce cholera risk, as well as the heterogeneity in outbreak dynamics from place to place, limits the precision and generalizability of our quantitative estimates. CONCLUSIONS: In this study, we found that CATIs using OCV, antibiotics, and water treatment interventions at an appropriate radius around cases could be an effective and efficient way to fight cholera epidemics. They can provide a complementary and efficient approach to mass intervention campaigns and may prove particularly useful during the initial phase of an outbreak, when there are few cases and few available resources, or in order to shorten the often protracted tails of cholera epidemics.

Four years of case-based surveillance of meningitis following the introduction of MenAfriVac in Moissala, Chad: lessons learned.

OBJECTIVE: Case-based surveillance of bacterial meningitis in sentinel districts has been recommended after the introduction of the conjugated vaccine against Neisseria meningitidis serogroup A (NmA), MenAfriVac, in the African meningitis belt. Here we report data and lessons learnt from four years of surveillance in the district of Moissala, Chad. METHODS: All suspected cases of meningitis were referred free of charge to the district hospital for lumbar puncture and treatment. Cerebrospinal fluid samples were tested with Pastorex latex agglutination in Moissala, and inoculated trans-isolate media were used for culture and PCR at the national reference laboratory and/or at the Norwegian Institute of Public Health. RESULTS: From July 2012 to December 2016, 237 suspected cases of meningitis were notified, and a specimen was collected from 224. Eighty-three samples were positive for a bacterial pathogen by culture, PCR or Pastorex, including 58 cases due to Streptococcus pneumoniae with only 28 of 49 pneumococcal meningitis confirmed by culture or PCR correctly identified by Pastorex. Four cases of NmA were detected by Pastorex, but none were confirmed by PCR. CONCLUSION: Implementation of case-based surveillance for meningitis is feasible in Chad, but has required political and technical engagement. Given the high proportion of S. pneumoniae and its poor detection by Pastorex, continued use of PCR is warranted for surveillance outside of outbreaks, and efforts to accelerate the introduction of pneumococcal conjugate vaccines are needed. Introduction of MenAfriVac in routine immunisation and future availability of a pentavalent meningococcal conjugate vaccine will be key elements for the sustained reduction in meningitis outbreaks in the area.

Mortality Rates during Cholera Epidemic, Haiti, 2010-2011.

The 2010 cholera epidemic in Haiti was one of the largest cholera epidemics ever recorded. To estimate the magnitude of the death toll during the first wave of the epidemic, we retrospectively conducted surveys at 4 sites in the northern part of Haiti. Overall, 70,903 participants were included; at all sites, the crude mortality rates (19.1-35.4 deaths/1,000 person-years) were higher than the expected baseline mortality rate for Haiti (9 deaths/1,000 person-years). This finding represents an excess of 3,406 deaths (2.9-fold increase) for the 4.4% of the Haiti population covered by these surveys, suggesting a substantially higher cholera mortality rate than previously reported.

Comparison of weight-for-height and mid-upper arm circumference (MUAC) in a therapeutic feeding programme in South Sudan: is MUAC alone a sufficient criterion for admission of children at high risk of mortality?

OBJECTIVE: The present study was performed to describe the operational implications of using mid-upper arm circumference (MUAC) as a single admission criterion for treatment of severe acute malnutrition in South Sudan. DESIGN: We performed a retrospective analysis of routine programme data of children with severe acute malnutrition aged 6-59 months admitted to a therapeutic feeding programme using weight-for-height Z-score (WHZ) and/or MUAC. To understand the implications of using MUAC as a single admission criterion, we compared patient characteristics and treatment outcomes for children admitted with MUAC<115 mm (irrespective of WHZ) v. children admitted with WHZ<-3 and MUAC≥115 mm. RESULTS: Of 2205 children included for analysis, 719 (32·6 %) were admitted to the programme with MUAC<115 mm and 1486 (67·4 %) with WHZ<-3 and MUAC≥115 mm. Children who would have been admitted using a single MUAC<115 mm criterion were more severely malnourished and more likely to be female and younger. Compared with children admitted with WHZ<-3 and MUAC≥115 mm, children who would have been admitted using MUAC<115 mm were less likely to recover (54 % v. 69 %) and had higher risk of death (4 % v. 1 %), but responded to treatment with greater weight and MUAC gains. MUAC<115 mm would have failed to identify 33 % of deaths, while 98 % were identified by WHZ<-3 alone and 100 % by MUAC<130 mm. CONCLUSIONS: The study shows that MUAC<115 mm identified more severely malnourished children with a higher risk of mortality but failed to identify a third of the children who died. Admission criteria for therapeutic feeding should be adapted to the programmatic context with consideration for both operational and public health implications.

Local discrepancies in measles vaccination opportunities: results of population-based surveys in Sub-Saharan Africa.

BACKGROUND: The World Health Organization recommends African children receive two doses of measles containing vaccine (MCV) through routine programs or supplemental immunization activities (SIA). Moreover, children have an additional opportunity to receive MCV through outbreak response immunization (ORI) mass campaigns in certain contexts. Here, we present the results of MCV coverage by dose estimated through surveys conducted after outbreak response in diverse settings in Sub-Saharan Africa. METHODS: We included 24 household-based surveys conducted in six countries after a non-selective mass vaccination campaign. In the majority (22/24), the survey sample was selected using probability proportional to size cluster-based sampling. Others used Lot Quality Assurance Sampling. RESULTS: In total, data were collected on 60,895 children from 2005 to 2011. Routine coverage varied between countries (>95% in Malawi and Kirundo province (Burundi) while <35% in N'Djamena (Chad) in 2005), within a country and over time. SIA coverage was <75% in most settings. ORI coverage ranged from >95% in Malawi to 71.4% [95% CI: 68.9-73.8] in N'Djamena (Chad) in 2005.In five sites, >5% of children remained unvaccinated after several opportunities. Conversely, in Malawi and DRC, over half of the children eligible for the last SIA received a third dose of MCV. CONCLUSIONS: Control pre-elimination targets were still not reached, contributing to the occurrence of repeated measles outbreak in the Sub-Saharan African countries reported here. Although children receiving a dose of MCV through outbreak response benefit from the intervention, ensuring that programs effectively target hard to reach children remains the cornerstone of measles control.

Médecins sans frontières experience in orthopedic surgery in postearthquake Haiti in 2010.

INTRODUCTION: During January 2010, a 7.0 magnitude earthquake struck Haiti, resulting in death and destruction for hundreds of thousands of people. This study describes the types of orthopedic procedures performed, the options for patient follow-up, and limitations in obtaining outcomes data in an emergency setting. PROBLEM: There is not a large body of data that describes larger orthopedic cohorts, especially those focusing on internal fixation surgeries in resource-poor settings in postdisaster regions. This article describes 248 injuries and over 300 procedures carried out in the Médecins Sans Frontières-Orthopedic Centre Paris orthopedic program. METHODS: Surgeries described in this report were limited to orthopedic procedures carried out under general anesthesia for all surgical patients. Exclusion factors included simple fracture reduction, debridement, dressing changes, and removal of hardware. This data was collected using both prospective and retrospective methods; prospective inpatient data were collected using a data collection form designed promptly after the earthquake and retrospective data collection was performed in October 2010. RESULTS: Of the 264 fractures, 204 were fractures of the major long bones (humerus, radius, femur, tibia). Of these 204 fractures of the major long bones, 34 (16.7%) were upper limb fractures and 170 (83.3%) were lower limb fractures. This cohort demonstrated a large number of open fractures of the lower limb and closed fractures of the upper limb. Fractures were treated according to their location and type. Of the 194 long bone fractures, the most common intervention was external fixation (36.5%) followed by traction (16.7%), nailing (15.1%), amputation (14.6%), and plating (9.9%). CONCLUSION: The number of fractures described in this report represents one of the larger orthopedic cohorts of patients treated in a single center in the aftermath of the 2010 earthquake in Haiti. The emergent surgical care described was carried out in difficult conditions, both in the hospital and the greater community. While outcome and complication data were limited, the proportion of patients attending follow-up most likely exceeded expectations and may reflect the importance of the rehabilitation center. This data demonstrates the ability of surgical teams to perform highly-specialized surgeries in a disaster zone, and also reiterates the need for access to essential and emergency surgical programs, which are an essential part of public health in low- and medium-resource settings.

Oral cholera vaccine coverage in Goma, Democratic Republic of the Congo, 2022, following 2019-2020 targeted preventative mass campaigns.

Background: In 2019-2020, preventative Oral Cholera Vaccine campaigns were conducted in 24/32 non-contiguous health areas of Goma, DR Congo. In August 2022, we measured coverage and factors potentially influencing success of the delivery strategy. Methods: We used random geo-sampled stratified cluster survey to estimate OCV coverage and assess population movement, diarrhea history, and reasons for non-vaccination. Results: 603 households were visited. Coverage with at least one dose was 46.4 % (95 %CI: 41.8-51.0), and 50.1 % (95 %CI: 45.4-54.8) in areas targeted by vaccination compared to 26.3 % (95 %CI: 19.2-34.9) in non-targeted areas. Additionally, 7.0 % of participants reported moving from outside Goma since 2019, and 5.4 % reported history of severe diarrhea. Absence and unawareness were the main reasons for non-vaccination. Conclusion: Results suggest that targeting non-contiguous urban areas had a coverage-diluting effect. Targeting entire geographically contiguous areas, adapted distribution, and regular catch-up campaigns are operational recommendations to reach higher coverages arising from the study.

Correction: High seroprevalence of antibodies against SARS-CoV-2 among healthcare workers 8 months after the first wave in Aden, Yemen.

[This corrects the article DOI: 10.1371/journal.pgph.0000767.].

Measles outbreak response immunization is context-specific: insight from the recent experience of Médecins Sans Frontières.

Andrea Minetti and colleagues compare measles outbreak responses from the Democratic Republic of the Congo and Malawi and argue that outbreak response strategies should be tailored to local measles epidemiology. Please see later in the article for the Editors' Summary.

Measles in Democratic Republic of Congo: an outbreak description from Katanga, 2010-2011.

BACKGROUND: The Democratic Republic of Congo experiences regular measles outbreaks. From September 2010, the number of suspected measles cases increased, especially in Katanga province, where Medecins sans Frontieres supported the Ministry of Health in responding to the outbreak by providing free treatment, reinforcing surveillance and implementing non-selective mass vaccination campaigns. Here, we describe the measles outbreak in Katanga province in 2010-2011 and the results of vaccine coverage surveys conducted after the mass campaigns. METHODS: The surveillance system was strengthened in 28 of the 67 health zones of the province and we conducted seven vaccination coverage surveys in 2011. RESULTS: The overall cumulative attack rate was 0.71% and the case fatality ratio was 1.40%. CONCLUSIONS: Early investigation of the age distribution of cases is a key to understanding the epidemic, and should guide the vaccination of priority age groups.

High mortality rates among COVID-19 intensive care patients in Iraq: insights from a retrospective cohort study at Médecins Sans Frontières supported hospital in Baghdad.

Background: The Coronavirus Disease 2019 (COVID-19) pandemic has highlighted the challenges of the healthcare system in Iraq, which has limited intensive care unit beds, medical personnel, and equipment, contributing to high infection rates and mortality. The main purpose of the study was to describe the clinical characteristics, the length of Intensive Care Unit (ICU) stay, and the mortality outcomes of COVID-19 patients admitted to the ICU during the first wave and two subsequent surges, spanning from September 2020 to October 2021, in addition to identify potential risk factors for ICU mortality. Methods: This retrospective cohort study analyzed data from COVID-19 patients admitted to the COVID-19 ICU at Al-Kindi Ministry of Health hospital in Baghdad, Iraq, between September 2020 and October 2021. Results: The study included 936 COVID-19 patients admitted to the ICU at Al-Kindi Hospital. Results showed a high mortality rate throughout all waves, with 60% of deaths due to respiratory failure. Older age, male gender, pre-existing medical conditions, ICU procedures, and complications were associated with increased odds of ICU mortality. The study also found a decrease in the number of complications and ICU procedures between the first and subsequent waves. There was no significant difference in the length of hospital stay between patients admitted during different waves. Conclusion: Despite improvements in critical care practices, the mortality rate did not significantly decrease during the second and third waves of the pandemic. The study highlights the challenges of high mortality rates among critical COVID-19 patients in low-resource settings and the importance of effective data collection to monitor clinical presentations and identify opportunities for improvement in ICU care.

Differential symptomology of possible and confirmed Ebola virus disease infection in the Democratic Republic of the Congo: a retrospective cohort study.

BACKGROUND: In its earliest phases, Ebola virus disease's rapid-onset, high fever, and gastrointestinal symptoms are largely indistinguishable from other infectious illnesses. We aimed to characterise the clinical indicators associated with Ebola virus disease to improve outbreak response. METHODS: In this retrospective analysis, we assessed routinely collected data from individuals with possible Ebola virus disease attending 30 Ebola health facilities in two provinces of the Democratic Republic of the Congo between Aug 1, 2018, and Aug 28, 2019. We used logistic regression analysis to model the probability of Ebola infection across 34 clinical variables and four types of possible Ebola virus disease exposures: contact with an individual known to have Ebola virus disease, attendance at any funeral, health facility consultation, or consultation with an informal health practitioner. FINDINGS: Data for 24 666 individuals were included. If a patient presented to care in the early symptomatic phase (ie, days 0-2), Ebola virus disease positivity was most associated with previous exposure to an individual with Ebola virus disease (odds ratio [OR] 11·9, 95% CI 9·1-15·8), funeral attendance (2·1, 1·6-2·7), or health facility consultations (2·1, 1·6-2·8), rather than clinical parameters. If presentation occurred on day 3 or later (after symptom onset), bleeding at an injection site (OR 33·9, 95% CI 12·7-101·3), bleeding gums (7·5, 3·7-15·4), conjunctivitis (2·4, 1·7-3·4), asthenia (1·9, 1·5-2·3), sore throat (1·8, 1·3-2·4), dysphagia (1·8, 1·4-2·3), and diarrhoea (1·6, 1·3-1·9) were additional strong predictors of Ebola virus disease. Some Ebola virus disease-specific signs were less prevalent among vaccinated individuals who were positive for Ebola virus disease when compared with the unvaccinated, such as dysphagia (-47%, p=0·0024), haematemesis (-90%, p=0·0131), and bleeding gums (-100%, p=0·0035). INTERPRETATION: Establishing the exact time an individual first had symptoms is essential to assessing their infection risk. An individual's exposure history remains of paramount importance, especially in the early phase. Ebola virus disease vaccination reduces symptom severity and should also be considered when assessing the likelihood of infection. These findings about symptomatology should be translated into practice during triage and should inform testing and quarantine procedures. FUNDING: Médecins Sans Frontières and its research affiliate Epicentre.

Seroprevalence of SARS-CoV-2 antibodies and retrospective mortality in two African settings: Lubumbashi, Democratic Republic of the Congo and Abidjan, Côte d'Ivoire.

Although seroprevalence studies have demonstrated the wide circulation of SARS-COV-2 in African countries, the impact on population health in these settings is still poorly understood. Using representative samples of the general population, we evaluated retrospective mortality and seroprevalence of anti-SARS-CoV-2 antibodies in Lubumbashi and Abidjan. The studies included retrospective mortality surveys and nested anti-SARS-CoV-2 antibody prevalence surveys. In Lubumbashi the study took place during April-May 2021 and in Abidjan the survey was implemented in two phases: July-August 2021 and October-November 2021. Crude mortality rates were stratified between pre-pandemic and pandemic periods and further investigated by age group and COVID waves. Anti-SARS-CoV-2 seroprevalence was quantified by rapid diagnostic testing (RDT) and laboratory-based testing (ELISA in Lubumbashi and ECLIA in Abidjan). In Lubumbashi, the crude mortality rate (CMR) increased from 0.08 deaths per 10 000 persons per day (pre-pandemic) to 0.20 deaths per 10 000 persons per day (pandemic period). Increases were particularly pronounced among <5 years old. In Abidjan, no overall increase was observed during the pandemic period (pre-pandemic: 0.05 deaths per 10 000 persons per day; pandemic: 0.07 deaths per 10 000 persons per day). However, an increase was observed during the third wave (0.11 deaths per 10 000 persons per day). The estimated seroprevalence in Lubumbashi was 15.7% (RDT) and 43.2% (laboratory-based). In Abidjan, the estimated seroprevalence was 17.4% (RDT) and 72.9% (laboratory-based) during the first phase of the survey and 38.8% (RDT) and 82.2% (laboratory-based) during the second phase of the survey. Although circulation of SARS-CoV-2 seems to have been extensive in both settings, the public health impact varied. The increases, particularly among the youngest age group, suggest indirect impacts of COVID and the pandemic on population health. The seroprevalence results confirmed substantial underdetection of cases through the national surveillance systems.

High seroprevalence of antibodies against SARS-CoV-2 among healthcare workers 8 months after the first wave in Aden, Yemen.

The true burden of COVID-19 in Yemen is underestimated. The healthcare system is dysfunctional and there is a high shortage of health care workers in the country. Testing for SARS-CoV-2 remains limited and official surveillance data is restricted to those who are severe or highly suspected. In this study, Médecins Sans Frontières (MSF) aimed to conduct serological screening using rapid tests for asymptomatic staff at the MSF Aden Trauma Center to determine the SARS-CoV-2 antibody seropositivity. Four months after the peak of the first wave, we offered all the staff at the MSF Aden Trauma Center PCR if symptomatic, and a baseline SARS-CoV-2 serology screening followed by follow-up screenings. A final round was scheduled four months after the baseline. A rapid serology lateral flow test, NG-Test IgM-IgG was used in all rounds and in the final round, an electrochemiluminescence immunoassay (ECLIA) (Elecsys Anti-SARS-CoV-2 assay). Univariate and multivariate analyses were used to identify risk factors for seropositivity. The level of agreement between the different serology assays used was investigated. Overall 69 out of 356 participants (19.4%, 95% CI 17.9-20.8) tested positive by NG-Test between September and November 2020. A sub-sample of 161 staff members were retested in January 2021. Of these, the NG-Test detected only 13 positive cases, whereas the ECLIA detected 109 positive cases. The adjusted seroprevalence by ECLIA was 59% (95%CI 52.2-65.9). The non-medical staff had significantly lower odds of seropositivity compared to the medical staff (AOR 0.43, 95% CI 0.15-0.7, p<0.001). The positive percent agreement between the two tests was very low (11%). Our results suggest a very high SARS-CoV-2 seroprevalence in healthcare workers in Yemen, highlighting the need for regular testing and rapid vaccination of all healthcare workers in the country.