Large Diffusion of Severe Acute Respiratory Syndrome Coronavirus 2 After the Successive Epidemiological Waves, Including Omicron, in Guinea and Cameroon: Implications for Vaccine Strategies.

Background: We aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence among the general population in Conakry, Guinea and Yaounde, Cameroon after the coronavirus disease 2019 Omicron wave. Methods: We conducted population-based, age-stratified seroprevalence surveys in Conakry and Yaounde (May and June 2022). We collected demographic and epidemiologic information and dried blood spot samples that were tested for SARS-CoV-2 immunoglobulin G (IgG) antibodies using recombinant nucleocapsid and spike proteins with Luminex technology. Results: Samples were obtained from 1386 and 1425 participants in Guinea and Cameroon, respectively. The overall age-standardized SARS-CoV-2 IgG seroprevalence against spike and nucleocapsid proteins was 71.57% (95% confidence interval [CI], 67.48%-75.33%) in Guinea and 74.71% (95% CI, 71.99%-77.25%) in Cameroon. Seroprevalence increased significantly with age categories. Female participants were more likely than male participants to be seropositive. The seroprevalence in unvaccinated participants was 69.6% (95% CI, 65.5%-73.41%) in Guinea and 74.8% (95% CI, 72.04%-77.38%) in Cameroon. In multivariate analysis, only age, sex, and education were independently associated with seropositivity. Conclusions: These findings show a high community transmission after the different epidemiological waves including Omicron, especially among people aged >40 years. In addition, our results suggest that the spread of SARS-CoV-2 has been underestimated as a significant proportion of the population has already contracted the virus and that vaccine strategies should focus on vulnerable populations.

High and Rapid Increase in Seroprevalence for SARS-CoV-2 in Conakry, Guinea: Results From 3 Successive Cross-Sectional Surveys (ANRS COV16-ARIACOV).

We conducted 3 successive seroprevalence surveys, 3 months apart, using multistage cluster sampling to measure the extent and dynamics of the severe acute respiratory syndrome coronavirus 2 epidemic in Conakry, the capital city of Guinea. Seroprevalence increased from 17.3% (95% CI, 12.4%-23.8%) in December 2020 during the first survey (S1) to 28.9% (95% CI, 25.6%-32.4%) in March/April 2021 (S2), then to 42.4% (95% CI, 39.5%-45.3%) in June 2021 (S3). This significant overall trend of increasing seroprevalence (P < .0001) was also significant in every age class, illustrating a sustained transmission within the whole community. These data may contribute to defining cost-effective response strategies.

Understanding Long-term Evolution and Predictors of Sequelae of Ebola Virus Disease Survivors in Guinea: A 48-Month Prospective, Longitudinal Cohort Study (PostEboGui).

BACKGROUND: Longitudinal analyses are needed to better understand long-term Ebola virus disease (EVD) sequelae. We aimed to estimate the prevalence, incidence, and duration of sequelae and to identify risk factors associated with symptom occurrence among EVD survivors in Guinea. METHODS: We followed 802 EVD survivors over 48 months and recorded clinical symptoms with their start/end dates. Prevalence, incidence, and duration of sequelae were calculated. Risk factors associated with symptom occurrence were assessed using an extended Cox model for recurrent events. RESULTS: Overall, the prevalence and incidence of all symptoms decreased significantly over time, but sequelae remained present 48 months after Ebola treatment center discharge with a prevalence of 30.68% (95% confidence interval [CI] 21.40-39.96) for abdominal, 30.55% (95% CI 20.68-40.41) for neurologic, 5.80% (95% CI 1.96-9.65) for musculoskeletal, and 4.24% (95% CI 2.26-6.23) for ocular sequelae. Half of all patients (50.70%; 95% CI 47.26-54.14) complained of general symptoms 2 years' postdischarge and 25.35% (95% CI 23.63-27.07) 4 years' post-discharge. Hemorrhage (hazard ratio [HR], 2.70; P = .007), neurologic (HR 2.63; P = .021), and general symptoms (HR 0.34; P = .003) in the EVD acute phase were significantly associated with the further occurrence of ocular sequelae, whereas hemorrhage (HR 1.91; P = .046) and abdominal (HR 2.21; P = .033) symptoms were significantly associated with musculoskeletal sequelae. CONCLUSIONS: Our findings provide new insight into the long-term clinical complications of EVD and their significant association with symptoms in the acute phase, thus reinforcing the importance of regular, long-term follow-up for EVD survivors.

Temporal evolution of the humoral antibody response after Ebola virus disease in Guinea: a 60-month observational prospective cohort study.

BACKGROUND: Insufficient long-term data are available on antibody kinetics in survivors of Ebola virus disease (EVD). Likewise, few studies, with very small sample sizes, have investigated cross-reactions between Ebolavirus spp. In this study, we aimed to assess the humoral antibody response and its determinants in survivors of EVD and assess cross-reactivity of antibodies between diverse Ebolavirus spp. METHODS: In this observational, prospective cohort study, we collected blood samples from patients from three recruitment sites in Guinea included in the Postebogui study, and we assessed IgG antibody binding to recombinant glycoprotein, nucleoprotein, and 40-kDa viral protein (VP40) of Zaire (EBOV), Bundibugyo (BDBV), and Sudan (SUDV) Ebolaviruses. Participants from the PostEbogui study, from whom we had at least one blood sample that could be tested for the presence of antibodies, were eligible for this analysis. Patients in the PostEbogui study were assessed clinically at inclusion, 1 month and 3 months later, and subsequently every 6 months for up to 60 months after discharge from the Ebola treatment centre. We explored predictors of glycoprotein, nucleoprotein, and VP40 antibody concentrations through a linear mixed model. A logistic mixed model was done to estimate the probability of seropositivity and associated determinants. We assessed cross-reactivity by use of hierarchical cluster analysis. FINDINGS: Of the 802 patients included in the Postebogui study, 687 were included in our analyses. 310 (45%) patients were men and 377 (55%) were women, with an overall median age at the time of the first blood sample of 27·3 years (IQR 19·5-38·2). We observed an overall significant decrease over time of EBOV antibodies, with antibodies against nucleoproteins decreasing more rapidly. At 60 months after discharge from the Ebola treatment centre, the probability of having antibodies against glycoproteins was 76·2% (95% CI 67·2-83·3), against nucleoproteins was 59·4% (46·3-71·3), and against VP40 was 60·9% (51·4-69·8). Persistence of EBOV RNA in semen was associated with higher concentrations of IgG antibodies against nucleoprotein EBOV antigens. Individually, we observed in some survivors an antibody wax-and-wane pattern. The proportion of cross-reactions was highest between glycoproteins from Kissidougou and Mayinga EBOV strains (94·5%, 95% CI 92·5-96·1), followed by EBOV VP40 and BDBV VP40 (88·3%, 85·7-90·6), and EBOV VP40 and SUDV VP40 (83·3%, 80·3-86·1). INTERPRETATION: The probability for survivors of EVD to have antibodies against one or more EBOV antigens remained high, although approximately 25% of survivors had undetectable antibodies, which could have implications, such as a possible decreasing population immunity, for future Ebola outbreaks in the same region. FUNDING: Reacting-Institut National de la Santé et de la Recherche Médicale, Institut de Recherche pour le Developpement, and Montpellier Université d'Excellence.

Prevalence of infection among asymptomatic and paucisymptomatic contact persons exposed to Ebola virus in Guinea: a retrospective, cross-sectional observational study.

BACKGROUND: The prevalence of Ebola virus infection among people who have been in contact with patients with Ebola virus disease remains unclear, but is essential to understand the dynamics of transmission. This study aimed to identify risk factors for seropositivity and to estimate the prevalence of Ebola virus infection in unvaccinated contact persons. METHODS: In this retrospective, cross-sectional observational study, we recruited individuals between May 12, 2016, and Sept 8, 2017, who had been in physical contact with a patient with Ebola virus disease, from four medical centres in Guinea (Conakry, Macenta, N'zérékoré, and Forécariah). Contact persons had to be 7 years or older and not diagnosed with Ebola virus disease. Participants were selected through the Postebogui survivors' cohort. We collected self-reported information on exposure and occurrence of symptoms after exposure using a questionnaire, and tested antibody response against glycoprotein, nucleoprotein, and 40-kDa viral protein of Zaire Ebola virus by taking a blood sample. The prevalence of Ebola virus infection was estimated with a latent class model. FINDINGS: 1721 contact persons were interviewed and given blood tests, 331 of whom reported a history of vaccination so were excluded, resulting in a study population of 1390. Symptoms were reported by 216 (16%) contact persons. The median age of participants was 26 years (range 7-88) and 682 (49%) were male. Seropositivity was identified in 18 (8·33%, 95% CI 5·01-12·80) of 216 paucisymptomatic contact persons and 39 (3·32%, 5·01-12·80) of 1174 (2-4) asymptomatic individuals (p=0·0021). Seropositivity increased with participation in burial rituals (adjusted odds ratio [aOR] 2·30, 95% CI 1·21-4·17; p=0·0079) and exposure to blood or vomit (aOR 2·15, 1·23-3·91; p=0·0090). Frequency of Ebola virus infection varied from 3·06% (95% CI 1·84-5·05) in asymptomatic contact persons who did not participate in burial rituals to 5·98% (2·81-8·18) in those who did, and from 7·17% (3·94-9·09) in paucisymptomatic contact persons who did not participate in burial rituals to 17·16% (12·42-22·31) among those who did. INTERPRETATION: This study provides a new assessment of the prevalence of Ebola virus infection among contact persons according to exposure, provides evidence for the occurrence of paucisymptomatic cases, and reinforces the importance of closely monitoring at-risk contact persons. FUNDING: Institut National de la Santé et de la Recherche Médicale, Reacting, the French Ebola Task Force, Institut de Recherche pour le Développement, and Montpellier University Of Excellence-University of Montpellier.

A 40-Month Follow-Up of Ebola Virus Disease Survivors in Guinea (PostEbogui) Reveals Long-Term Detection of Ebola Viral Ribonucleic Acid in Semen and Breast Milk.

BACKGROUND: With the increasing frequency and impact of Ebola virus disease (EVD) outbreaks illustrated by recent epidemics, a good understanding of the extent of viral persistance or ribonucleic acid (RNA) detection in body fluids from survivors is urgently needed. METHODS: Ebola viral RNA shedding was studied with molecular assays in semen (n = 1368), urine (n = 1875), cervicovaginal fluid (n = 549), saliva (n = 900), breast milk (n = 168), and feces (n = 558) from EVD survivors in Guinea (PostEbogui cohort, n = 802) at a regular base period until 40 months after inclusion. RESULTS: Twenty-seven of 277 (9.8%) male survivors tested positive for Ebola RNA in at least 1 semen sample. The probability of remaining positive for Ebola RNA in semen was estimated at 93.02% and 60.12% after 3 and 6 months. Viral RNA in semen was more frequent in patients with eye pain (P = .036), joint pain (P = .047), and higher antibody levels to Ebola virus antigens (nucleoprotein [P = .001], glycoprotein [P = .05], and viral protein-40 [P = .05]). Ebola RNA was only rarely detected in the following body fluids from EVD survivors: saliva (1 of 454), urine (2 of 593), breast milk (2 of 168), cervicovaginal secretions (0 of 273), and feces (0 of 330). Ribonucleic acid was detected in breast milk 1 month after delivery but 500 days after discharge of Ebola treatment unit (ETU) in 1 woman who became pregnant 7 months after discharge from the ETU. CONCLUSIONS: The frequency and potential long-term presence of viral RNA in semen confirmed that systematic prevention measures in male survivors are required. Our observation in breast milk suggests that our knowledge on viral reservoir in immune-privileged sites and its impact are still incomplete.

Multidisciplinary assessment of post-Ebola sequelae in Guinea (Postebogui): an observational cohort study.

BACKGROUND: The high number of survivors from the 2013-16 west African outbreak of Ebola virus disease (EVD) has raised several new issues: long-term clinical complications, psychosocial consequences, risks of EVD reactivation, and secondary transmission due to viral persistence in body fluids. We aimed to assess long-term clinical, psychosocial, and viral outcomes in EVD survivors in Guinea. METHODS: In this multidisciplinary observational cohort study, we recruited patients aged 1 year or more in four sites in Guinea (Donka National Hospital, Conakry; Macenta Prefectoral Hospital, Macenta; N'zérékoré Regional Hospital, N'zérékoré; and Forécariah Prefectoral Hospital, Forécariah) following discharge from any Ebola treatment centre in Guinea. Eligible patients had had laboratory-confirmed EVD and had then been declared clear of the virus in the blood. All consenting patients were included, with no exclusion criteria. Trained clinicians assessed patients at enrolment to the cohort, recording clinical symptoms and signs of depression. We did routine blood examinations and examined viral persistence in body fluids using RT-PCR. We did psychological evaluations using questionnaires developed for different age groups. Follow-up is planned to 2 years, and here we present findings at enrolment. FINDINGS: Between March 23, 2015, and July 11, 2016, we recruited 802 patients, of whom 360 (45%) were male, 442 (55%) were female; 158 (20%) were younger than 18 years. The median age was 28·4 years (range 1·0-79·9, IQR 19·4-39·8). The median delay after discharge was 350 days (IQR 223-491). The most frequent symptoms were general symptoms (324 [40%] patients), musculoskeletal pain (303 [38%]), headache (278 [35%]), depression (124 [17%] of 713 responses), abdominal pain (178 [22%]), and ocular disorders (142 [18%]). More adults than children had at least one clinical symptom (505 [78%] vs 101 [64%], p<0·0003), ocular complications (124 [19%] vs 18 [11%], p=0·0200), or musculoskeletal symptoms (274 [43%] vs 29 [18%], p<0·0001). A positive RT-PCR in semen was found in ten (5%) of 188 men, at a maximum of 548 days after disease onset. 204 (26%) of 793 patients reported stigmatisation. Ocular complications were more frequent at enrolment than at discharge (142 [18%] vs 61 [8%] patients). INTERPRETATION: Post-EVD symptoms can remain long after recovery and long-term viral persistence in semen is confirmed. The results justify calls for regular check-ups of survivors at least 18 months after recovery. FUNDING: INSERM/Reacting, the French Ebola Task Force, and Institut de Recherche pour le Développement.