Conference Material > Abstract
Nesbitt RC
Epicentre Scientific Day Paris 2023. 2023 June 8
BACKGROUND
Hepatitis E causes high mortality among pregnant women with case fatality risks of 10-25%, and adverse fetal outcomes. Hecolin® is a safe and efficacious vaccine against Hepatitis E, but there is an evidence gap on its safety in pregnant women. In 2015 the WHO recommended its use in response to outbreaks, including vaccinating pregnant women. The first mass reactive vaccination campaign against Hepatitis E was conducted in Bentiu including pregnant women and achieved high administrative vaccination coverage. We aimed to document pregnancy outcomes in a cohort of vaccinated and non-vaccinated pregnant women.
METHODS
An exhaustive pregnancy census was conducted after the second vaccination round from 16 May to 30 June 2022 to recruit women who were pregnant between 1 January 2022 and the interview date. Women were recontacted a minimum of 28 days after expected delivery to assess pregnancy outcome. Categorization of the cohort according to timing of potential vaccine exposure in pregnancy and regression models to evaluate the association between at least one dose in pregnancy and pregnancy outcomes is ongoing.
RESULTS
Of 20,674 women of childbearing age who consented for interview, 3,458 (16.7%) reported being pregnant since 1 January 2022. Women were a mean of 25.5 years old, had a median of 2 previous pregnancies (0-11), and 21 (0.6%) reported experiencing jaundice during their current pregnancy. Overall, 2723 (78.7%) women received at least one dose of Hecolin®. Access to delivery care was high, with 90% of women delivering in a health facility; 357 (10.3%) women reported a complication during delivery and 16 (0.5%) reported a caesarean section. According to interview, 3233 (93.5%) women had a livebirth, and 225 (6.9%) had a pregnancy loss, including 57 (1.6%) reported stillbirths, translating to a stillbirth rate of 17.6/1000 pregnancies, compared to the national estimate of 25.8/1000 pregnancies.
CONCLUSION
It was feasible to implement an observational study on the safety of vaccination in pregnancy alongside the first deployment of Hecolin® in a humanitarian emergency setting. Access to delivery care is reflected in the lower than national average rate of stillbirth in the camp. Results are expected to narrow the evidence gap on the safety of this vaccine in pregnancy.
KEY MESSAGE
A cohort study on the safety of vaccination in pregnancy was implemented alongside the first deployment of Hecolin® in a humanitarian emergency setting. Preliminary results show overall high coverage with at least one dose and access to delivery care among women in the cohort
This abstract is not to be quoted for publication.
Hepatitis E causes high mortality among pregnant women with case fatality risks of 10-25%, and adverse fetal outcomes. Hecolin® is a safe and efficacious vaccine against Hepatitis E, but there is an evidence gap on its safety in pregnant women. In 2015 the WHO recommended its use in response to outbreaks, including vaccinating pregnant women. The first mass reactive vaccination campaign against Hepatitis E was conducted in Bentiu including pregnant women and achieved high administrative vaccination coverage. We aimed to document pregnancy outcomes in a cohort of vaccinated and non-vaccinated pregnant women.
METHODS
An exhaustive pregnancy census was conducted after the second vaccination round from 16 May to 30 June 2022 to recruit women who were pregnant between 1 January 2022 and the interview date. Women were recontacted a minimum of 28 days after expected delivery to assess pregnancy outcome. Categorization of the cohort according to timing of potential vaccine exposure in pregnancy and regression models to evaluate the association between at least one dose in pregnancy and pregnancy outcomes is ongoing.
RESULTS
Of 20,674 women of childbearing age who consented for interview, 3,458 (16.7%) reported being pregnant since 1 January 2022. Women were a mean of 25.5 years old, had a median of 2 previous pregnancies (0-11), and 21 (0.6%) reported experiencing jaundice during their current pregnancy. Overall, 2723 (78.7%) women received at least one dose of Hecolin®. Access to delivery care was high, with 90% of women delivering in a health facility; 357 (10.3%) women reported a complication during delivery and 16 (0.5%) reported a caesarean section. According to interview, 3233 (93.5%) women had a livebirth, and 225 (6.9%) had a pregnancy loss, including 57 (1.6%) reported stillbirths, translating to a stillbirth rate of 17.6/1000 pregnancies, compared to the national estimate of 25.8/1000 pregnancies.
CONCLUSION
It was feasible to implement an observational study on the safety of vaccination in pregnancy alongside the first deployment of Hecolin® in a humanitarian emergency setting. Access to delivery care is reflected in the lower than national average rate of stillbirth in the camp. Results are expected to narrow the evidence gap on the safety of this vaccine in pregnancy.
KEY MESSAGE
A cohort study on the safety of vaccination in pregnancy was implemented alongside the first deployment of Hecolin® in a humanitarian emergency setting. Preliminary results show overall high coverage with at least one dose and access to delivery care among women in the cohort
This abstract is not to be quoted for publication.
Conference Material > Abstract
Diallo AK, Bossard C
Epicentre Scientific Day Paris 2023. 2023 June 8
BACKGROUND AND AIMS
Early psychosocial stimulation with disadvantaged infants can lead to short- and long-term benefits in cognitive and social development. Programs with multiple
components, including health, nutrition, and psychosocial stimulation have shown to be the most successful at enhancing the rehabilitation of severe acute malnourished (SAM) children. The STIMNUT study assesses the feasibility of integrating an adapted version of the ‘Follow-Up of Severe Acute Malnourished children’ (FUSAM) protocol developed by Action Contre la Faim into the Médecins Sans Frontières (MSF) Therapeutic Feeding Programme in Koutiala (Mali) for SAM children aged 6-23 months and their primary caregivers.
METHODS
A convergent mixed methods study was implemented between July 2022 and May 2023 in two outpatient health facilities and the general hospital in Koutiala. An adaptation of the PRECEDE-PROCEED conceptual framework was used to adapt, implement and evaluate the psychosocial stimulation intervention. The study was
divided into 3 successive phases: (1) a mixed methods initial assessment at community level, (2) the contextual adaptation of the FUSAM protocol through a participatory approach (PAR) and (3) an assessment of its acceptability. For this assessment, 15 individual interviews with mothers were conducted. Qualitative and quantitative data were analyzed and interpreted concurrently.
RESULTS
During the PAR process, various stakeholders including, development workers and health professionals, parents of SAM children and traditional healers, worked together to practically adapt the intervention. They proposed for instance to include a community-level ceremony at the beginning of the intervention with traditional authorities, villages chiefs and other local stakeholders to increase its appropriation and to sensitize community members. During phase 3, a total of 149 psychosocial stimulation sessions (122 individual and 27 collective) were delivered by a team of 3 psychosocial workers to the 36 families included. The preliminary acceptability results showed that the sessions were well appreciated by the mothers. They became more acceptable as the intervention progressed because of the resulting positive changes in their children’s wellbeing, in theirs and their families’ relationship with their children, and in the mothers' relationships with their husbands and extended family.
CONCLUSION
The implementation of the adapted version of FUSAM protocol and its acceptability assessment at primary and secondary health care levels will now be used to inform the further deployment of the intervention. In particular, the results have allowed the development of a framework for the StimNut intervention to make it locally relevant and to guide its reproducibility in other contexts.
KEY MESSAGE
StimNut is a mixed method feasibility study on the integration of a psychosocial stimulation intervention into the standard nutritional care for SAM children aged 6-23 months In Koutiala, Mali.
This abstract is not to be quoted for publication.
Early psychosocial stimulation with disadvantaged infants can lead to short- and long-term benefits in cognitive and social development. Programs with multiple
components, including health, nutrition, and psychosocial stimulation have shown to be the most successful at enhancing the rehabilitation of severe acute malnourished (SAM) children. The STIMNUT study assesses the feasibility of integrating an adapted version of the ‘Follow-Up of Severe Acute Malnourished children’ (FUSAM) protocol developed by Action Contre la Faim into the Médecins Sans Frontières (MSF) Therapeutic Feeding Programme in Koutiala (Mali) for SAM children aged 6-23 months and their primary caregivers.
METHODS
A convergent mixed methods study was implemented between July 2022 and May 2023 in two outpatient health facilities and the general hospital in Koutiala. An adaptation of the PRECEDE-PROCEED conceptual framework was used to adapt, implement and evaluate the psychosocial stimulation intervention. The study was
divided into 3 successive phases: (1) a mixed methods initial assessment at community level, (2) the contextual adaptation of the FUSAM protocol through a participatory approach (PAR) and (3) an assessment of its acceptability. For this assessment, 15 individual interviews with mothers were conducted. Qualitative and quantitative data were analyzed and interpreted concurrently.
RESULTS
During the PAR process, various stakeholders including, development workers and health professionals, parents of SAM children and traditional healers, worked together to practically adapt the intervention. They proposed for instance to include a community-level ceremony at the beginning of the intervention with traditional authorities, villages chiefs and other local stakeholders to increase its appropriation and to sensitize community members. During phase 3, a total of 149 psychosocial stimulation sessions (122 individual and 27 collective) were delivered by a team of 3 psychosocial workers to the 36 families included. The preliminary acceptability results showed that the sessions were well appreciated by the mothers. They became more acceptable as the intervention progressed because of the resulting positive changes in their children’s wellbeing, in theirs and their families’ relationship with their children, and in the mothers' relationships with their husbands and extended family.
CONCLUSION
The implementation of the adapted version of FUSAM protocol and its acceptability assessment at primary and secondary health care levels will now be used to inform the further deployment of the intervention. In particular, the results have allowed the development of a framework for the StimNut intervention to make it locally relevant and to guide its reproducibility in other contexts.
KEY MESSAGE
StimNut is a mixed method feasibility study on the integration of a psychosocial stimulation intervention into the standard nutritional care for SAM children aged 6-23 months In Koutiala, Mali.
This abstract is not to be quoted for publication.
Conference Material > Abstract
Thadhani TAF, Phillips EY
Epicentre Scientific Day Paris 2023. 2023 June 8
BACKGROUND
The World Health Organization recommends the use of computer-aided detection (CAD) in conjunction with chest X-rays (CXR) for tuberculosis (TB) screening and triaging in individuals aged 15 and above. This study assessed the feasibility of implementing CAD for TB active case finding (ACF) in Tondo, Manila, Philippines, including a crucial calibration process to determine the appropriate threshold for referring individuals for TB confirmatory testing.
METHODS
We conducted a prospective description of programmatic activities, TB ACF of individuals aged 15 years and above using CAD, and a mixed-methods feasibility and acceptability study in the catchment area of four health centres in Tondo. The calibration process employed an informal mixed methods approach to define, and reactively adjust, a threshold based on the Xpert MTB/Rif positivity rate, Xpert capacity, radiologists' sensitivity and user acceptability. Patients with a CAD score above the defined threshold were directed for sputum collection and Xpert testing.
RESULTS
The initial threshold, set at 25, resulted in a 35% referral rate for Xpert testing, which was subsequently increased to 28 (34% referral) to align with Xpert system capacity. 4,853 patients were included, with 13% testing positive on the symptom screening. The Xpert positivity rate was 5% among individuals screened, 13% among individuals tested, and 15% among individuals with a CAD score of 28 or higher. Users found CAD4TB® both feasible and acceptable, provided there were dedicated human resources with technical capacity for CAD implementation and the project design accounted for CAD limitations. The use of CAD increased screening capacity and supported decision-making.
CONCLUSION
The ACF conducted in Tondo revealed a remarkably high positivity rate among the screened individuals. CAD enables the rapid screening of patients in the community with reduced turnaround times. If the implementation accounts for the limitations identified, CAD can be a powerful tool for TB screening.
KEY MESSAGE
CAD4TB® implementation in Tondo, Manila, was assessed for TB screening feasibility. Promising results indicate increased capacity and support for decision-making, emphasizing potential as a powerful tool.
This abstract is not to be quoted for publication.
The World Health Organization recommends the use of computer-aided detection (CAD) in conjunction with chest X-rays (CXR) for tuberculosis (TB) screening and triaging in individuals aged 15 and above. This study assessed the feasibility of implementing CAD for TB active case finding (ACF) in Tondo, Manila, Philippines, including a crucial calibration process to determine the appropriate threshold for referring individuals for TB confirmatory testing.
METHODS
We conducted a prospective description of programmatic activities, TB ACF of individuals aged 15 years and above using CAD, and a mixed-methods feasibility and acceptability study in the catchment area of four health centres in Tondo. The calibration process employed an informal mixed methods approach to define, and reactively adjust, a threshold based on the Xpert MTB/Rif positivity rate, Xpert capacity, radiologists' sensitivity and user acceptability. Patients with a CAD score above the defined threshold were directed for sputum collection and Xpert testing.
RESULTS
The initial threshold, set at 25, resulted in a 35% referral rate for Xpert testing, which was subsequently increased to 28 (34% referral) to align with Xpert system capacity. 4,853 patients were included, with 13% testing positive on the symptom screening. The Xpert positivity rate was 5% among individuals screened, 13% among individuals tested, and 15% among individuals with a CAD score of 28 or higher. Users found CAD4TB® both feasible and acceptable, provided there were dedicated human resources with technical capacity for CAD implementation and the project design accounted for CAD limitations. The use of CAD increased screening capacity and supported decision-making.
CONCLUSION
The ACF conducted in Tondo revealed a remarkably high positivity rate among the screened individuals. CAD enables the rapid screening of patients in the community with reduced turnaround times. If the implementation accounts for the limitations identified, CAD can be a powerful tool for TB screening.
KEY MESSAGE
CAD4TB® implementation in Tondo, Manila, was assessed for TB screening feasibility. Promising results indicate increased capacity and support for decision-making, emphasizing potential as a powerful tool.
This abstract is not to be quoted for publication.
Conference Material > Abstract
Natukunda N
Epicentre Scientific Day Paris 2023. 2023 June 8
BACKGROUND
Childhood tuberculosis is underdiagnosed at low-level healthcare settings because of poor access to specimen collection, rapid molecular testing, clinical evaluation and chest radiography. Decentralizing childhood tuberculosis diagnosis at district hospital (DH) and primary health centre (PHC) levels could improve case detection.
METHODS
TB-Speed decentralisation is an operational research using a pre-post intervention cross-sectional design in 12 DHs and 47 PHCs of 12 districts in Cambodia, Cameroon, Côte d’Ivoire, Mozambique, Sierra Leone and Uganda. The intervention included a comprehensive childhood tuberculosis diagnosis package consisting of systematic tuberculosis screening for all under-15-year-old sick children, clinical evaluation, Xpert Ultra-testing on one nasopharyngeal aspirate (NPA) and stool samples, and chest radiography for children with presumptive tuberculosis, using either PHC-focused or DH-focused decentralization approaches. We collected aggregated and individual data for children whose parents consented. We present the comparison of the proportion of tuberculosis case detected pre-intervention from August 2018 to Nov 2019 versus post-intervention from March 2020 to September 2021, overall and by decentralization approach, and the uptake and acceptability of the diagnostic package in Uganda.
FINDINGS
In Uganda, 52233 and 46035 children attended care pre-intervention versus post-intervention respectively. 26/52233 (0.05%) and 42/46035 (0.09%) children were diagnosed with tuberculosis pre-intervention and post-intervention respectively, p-value=0.114. In DH-focused district, it was 10/24208 (0.04%) and 23/17914 (0.1%) pre-intervention and post-intervention respectively, and 16/28025 (0.06%) and 19/28121 (0.1%) for PHC-districts, respectively. The uptake of TB screening was 43104/46035 (93.6%) overall, among the 732 enrolled children 724/ and 532 had a valid Ultra result using NPA and stool, respectively. Health care workers overall experienced decentralized childhood TB diagnostic as acceptable, with NPA and stool sample collection feasible both at DH and PHC.
CONCLUSION
Decentralizing innovative childhood tuberculosis diagnosis can increase tuberculosis case detection with limited impact when using the PHC decentralization approach.
KEY MESSAGE
Although decentralizing childhood TB diagnosis is acceptable, overcoming feasibility issues may improve the effective implementation and scale-up of such interventions at low levels of care.
This abstract is not to be quoted for publication.
Childhood tuberculosis is underdiagnosed at low-level healthcare settings because of poor access to specimen collection, rapid molecular testing, clinical evaluation and chest radiography. Decentralizing childhood tuberculosis diagnosis at district hospital (DH) and primary health centre (PHC) levels could improve case detection.
METHODS
TB-Speed decentralisation is an operational research using a pre-post intervention cross-sectional design in 12 DHs and 47 PHCs of 12 districts in Cambodia, Cameroon, Côte d’Ivoire, Mozambique, Sierra Leone and Uganda. The intervention included a comprehensive childhood tuberculosis diagnosis package consisting of systematic tuberculosis screening for all under-15-year-old sick children, clinical evaluation, Xpert Ultra-testing on one nasopharyngeal aspirate (NPA) and stool samples, and chest radiography for children with presumptive tuberculosis, using either PHC-focused or DH-focused decentralization approaches. We collected aggregated and individual data for children whose parents consented. We present the comparison of the proportion of tuberculosis case detected pre-intervention from August 2018 to Nov 2019 versus post-intervention from March 2020 to September 2021, overall and by decentralization approach, and the uptake and acceptability of the diagnostic package in Uganda.
FINDINGS
In Uganda, 52233 and 46035 children attended care pre-intervention versus post-intervention respectively. 26/52233 (0.05%) and 42/46035 (0.09%) children were diagnosed with tuberculosis pre-intervention and post-intervention respectively, p-value=0.114. In DH-focused district, it was 10/24208 (0.04%) and 23/17914 (0.1%) pre-intervention and post-intervention respectively, and 16/28025 (0.06%) and 19/28121 (0.1%) for PHC-districts, respectively. The uptake of TB screening was 43104/46035 (93.6%) overall, among the 732 enrolled children 724/ and 532 had a valid Ultra result using NPA and stool, respectively. Health care workers overall experienced decentralized childhood TB diagnostic as acceptable, with NPA and stool sample collection feasible both at DH and PHC.
CONCLUSION
Decentralizing innovative childhood tuberculosis diagnosis can increase tuberculosis case detection with limited impact when using the PHC decentralization approach.
KEY MESSAGE
Although decentralizing childhood TB diagnosis is acceptable, overcoming feasibility issues may improve the effective implementation and scale-up of such interventions at low levels of care.
This abstract is not to be quoted for publication.
Conference Material > Abstract
Langendorf C
Epicentre Scientific Day Paris 2023. 2023 June 8
BACKGROUND
Patients with advanced HIV disease (AHD), defined as WHO clinical stage 3 or 4 and/or CD4<200, have a high risk of death. One common cause of death is invasive bacterial infection (IBI, i.e., septicemia or meningitis). The global increase of antibiotic resistance threatens current treatments against bacterial infections. This study aims to describe the burden of IBI among patients with AHD to guide empirical treatment protocols.
METHODS
This is a prospective, descriptive study implemented at Kabinda General Hospital in Kinshasa, Democratic Republic of Congo (DRC). All patients with AHD and a blood or cerebrospinal fluid (CSF) culture collected because of: 1) fever/hypothermia and/or signs of shock, on admission or during hospitalization, and/or 2) previous exposure to care (<30 days), were eligible to participate. Clinical and bacteriological data were collected. An IBI was defined as a positive blood or CSF culture, and then categorized as: 1) community-acquired or healthcare-associated, if occurring =48 hours since hospitalization, and contingent on previous exposure to care (<30 days), or 2) hospital-acquired, if occurring >48 hours after hospitalization.
RESULTS
From August 2021 to July 2022, we included 997 patients, corresponding to 1198 hospitalizations with =1 blood and/or CSF culture. The proportions of community-acquired, healthcare-associated, and hospital-acquired IBI among hospitalizations were 5.9% (71/1198), 9.2% (110/1198), and 3.5% (42/1198), respectively. The main bacterial agents responsible for community-acquired and healthcare-associated IBI were non-Typhi Salmonella followed by Gram-positive Cocci, while K. pneumoniae was most common in hospital-acquired IBI. The levels of antibiotic susceptibility among Enterobacterales were similar between community-acquired and healthcare-associated IBI, with low susceptibility to ceftriaxone and ciprofloxacin, but high susceptibility to carbapenems and azithromycin.
CONCLUSION
We confirmed alarming levels of antibiotic resistance among patients with ADH in the DRC. Discussions are ongoing to translate results into practice, in particular to target broad spectrum empirical antibiotics.
KEY MESSAGE
Invasive bacterial infections among hospitalized patients with advanced HIV in Kinshasa showed high levels of antibiotic resistance regardless of their recent, previous exposure to care.
This abstract is not to be quoted for publication.
Patients with advanced HIV disease (AHD), defined as WHO clinical stage 3 or 4 and/or CD4<200, have a high risk of death. One common cause of death is invasive bacterial infection (IBI, i.e., septicemia or meningitis). The global increase of antibiotic resistance threatens current treatments against bacterial infections. This study aims to describe the burden of IBI among patients with AHD to guide empirical treatment protocols.
METHODS
This is a prospective, descriptive study implemented at Kabinda General Hospital in Kinshasa, Democratic Republic of Congo (DRC). All patients with AHD and a blood or cerebrospinal fluid (CSF) culture collected because of: 1) fever/hypothermia and/or signs of shock, on admission or during hospitalization, and/or 2) previous exposure to care (<30 days), were eligible to participate. Clinical and bacteriological data were collected. An IBI was defined as a positive blood or CSF culture, and then categorized as: 1) community-acquired or healthcare-associated, if occurring =48 hours since hospitalization, and contingent on previous exposure to care (<30 days), or 2) hospital-acquired, if occurring >48 hours after hospitalization.
RESULTS
From August 2021 to July 2022, we included 997 patients, corresponding to 1198 hospitalizations with =1 blood and/or CSF culture. The proportions of community-acquired, healthcare-associated, and hospital-acquired IBI among hospitalizations were 5.9% (71/1198), 9.2% (110/1198), and 3.5% (42/1198), respectively. The main bacterial agents responsible for community-acquired and healthcare-associated IBI were non-Typhi Salmonella followed by Gram-positive Cocci, while K. pneumoniae was most common in hospital-acquired IBI. The levels of antibiotic susceptibility among Enterobacterales were similar between community-acquired and healthcare-associated IBI, with low susceptibility to ceftriaxone and ciprofloxacin, but high susceptibility to carbapenems and azithromycin.
CONCLUSION
We confirmed alarming levels of antibiotic resistance among patients with ADH in the DRC. Discussions are ongoing to translate results into practice, in particular to target broad spectrum empirical antibiotics.
KEY MESSAGE
Invasive bacterial infections among hospitalized patients with advanced HIV in Kinshasa showed high levels of antibiotic resistance regardless of their recent, previous exposure to care.
This abstract is not to be quoted for publication.
Conference Material > Abstract
Camacho A
Epicentre Scientific Day Paris 2023. 2023 June 8
BACKGROUND
Lassa fever (LF), a haemorrhagic illness caused by the Lassa fever virus (LASV), is endemic in West Africa causing an estimated 300 000 to 500 000 cases and 5 000 fatalities every year. Due to its pandemic potential, LF has been placed on the WHO's list of priority pathogens in order to speed up the development of a safe and effective vaccine. However, the design of successful vaccine trials depends on the true prevalence and incidence rates of LF, which are unknown as infections are often asymptomatic and clinical presentations are varied. The aim of the Enable Lassa research programme is to estimate the incidences of LASV infection and LF disease in five West African countries.
METHODS
We conducted a prospective cohort study in Benin, Guinea, Liberia, Nigeria (three sites), and Sierra Leone from 2020 to 2023, with 24 months of follow-up. Each site assessed the incidence of LASV infection, LF disease, or both. When both incidences are assessed the LASV cohort (n = 1 000 per site) was drawn from the LF cohort (n = 5 000 per site). During recruitment participants completed questionnaires on household composition, socioeconomic status, demographic characteristics, and LF history, and blood samples were collected to determine IgG LASV serostatus. LF disease cohort participants were contacted biweekly to identify acute febrile cases, from whom blood samples were drawn to test for active LASV infection using RT-PCR. LASV infection cohort participants were asked for a blood sample every six months to assess LASV IgG serostatus.
RESULTS
Interim results were obtained in October 2022 using partial data. We focus here on the Nigeria-Edo cohort with a follow-up period of 22 months and 3 serological time-points available (T0, T6, T12). We found a baseline seroprevalence of 43% (95% CI: 42% - 45%), an incidence rate of LASV infection of 13% (10% - 16%) and an incidence rate of LF disease of 0.2% (0.1% - 0.3%). These results suggest that LASV infection is common, but LF disease is rare in hotspot communities. Furthermore, our results suggest that pre-exposure to LASV may temporarily reduce the risk of LF disease. Finally, we found evidence that children may be at greater risk of LF disease than adults due to lower pre-exposure.
CONCLUSION
This is the first epidemiological study to measure the incidence of LF disease and LASV infection in West Africa. The estimates will serve as a basis for the design of future vaccine efficacy trials. The interim results, although limited due to partial data, already suggest that a large sample of several tens of thousands of participants will be required and that children should be included, provided that the candidate vaccine is safe and immunogenic in this group.
KEY MESSAGE
Incidence of Lassa fever is needed to inform vaccine trials. Preliminary results show frequent infections but rare disease, suggesting the need for large vaccine trials.
This abstract is not to be quoted for publication.
Lassa fever (LF), a haemorrhagic illness caused by the Lassa fever virus (LASV), is endemic in West Africa causing an estimated 300 000 to 500 000 cases and 5 000 fatalities every year. Due to its pandemic potential, LF has been placed on the WHO's list of priority pathogens in order to speed up the development of a safe and effective vaccine. However, the design of successful vaccine trials depends on the true prevalence and incidence rates of LF, which are unknown as infections are often asymptomatic and clinical presentations are varied. The aim of the Enable Lassa research programme is to estimate the incidences of LASV infection and LF disease in five West African countries.
METHODS
We conducted a prospective cohort study in Benin, Guinea, Liberia, Nigeria (three sites), and Sierra Leone from 2020 to 2023, with 24 months of follow-up. Each site assessed the incidence of LASV infection, LF disease, or both. When both incidences are assessed the LASV cohort (n = 1 000 per site) was drawn from the LF cohort (n = 5 000 per site). During recruitment participants completed questionnaires on household composition, socioeconomic status, demographic characteristics, and LF history, and blood samples were collected to determine IgG LASV serostatus. LF disease cohort participants were contacted biweekly to identify acute febrile cases, from whom blood samples were drawn to test for active LASV infection using RT-PCR. LASV infection cohort participants were asked for a blood sample every six months to assess LASV IgG serostatus.
RESULTS
Interim results were obtained in October 2022 using partial data. We focus here on the Nigeria-Edo cohort with a follow-up period of 22 months and 3 serological time-points available (T0, T6, T12). We found a baseline seroprevalence of 43% (95% CI: 42% - 45%), an incidence rate of LASV infection of 13% (10% - 16%) and an incidence rate of LF disease of 0.2% (0.1% - 0.3%). These results suggest that LASV infection is common, but LF disease is rare in hotspot communities. Furthermore, our results suggest that pre-exposure to LASV may temporarily reduce the risk of LF disease. Finally, we found evidence that children may be at greater risk of LF disease than adults due to lower pre-exposure.
CONCLUSION
This is the first epidemiological study to measure the incidence of LF disease and LASV infection in West Africa. The estimates will serve as a basis for the design of future vaccine efficacy trials. The interim results, although limited due to partial data, already suggest that a large sample of several tens of thousands of participants will be required and that children should be included, provided that the candidate vaccine is safe and immunogenic in this group.
KEY MESSAGE
Incidence of Lassa fever is needed to inform vaccine trials. Preliminary results show frequent infections but rare disease, suggesting the need for large vaccine trials.
This abstract is not to be quoted for publication.
Conference Material > Video (talk)
Yakum MN
Epicentre Scientific Day Paris 2023. 2023 June 8
English
Français
Conference Material > Video (talk)
Lightowler M
Epicentre Scientific Day Paris 2023. 2023 June 8
English
Français
Conference Material > Video (talk)
Simons E
Epicentre Scientific Day Paris 2023. 2023 June 8
English
Français
Conference Material > Video (talk)
Broban A
Epicentre Scientific Day Paris 2023. 2023 June 8
English
Français