Caregiver acceptance of malaria vaccination for children under 5 years of age and associated factors: cross-sectional household survey, Guinea and Sierra Leone, 2022.

BACKGROUND: Malaria is a leading cause of death and reduced life span in Guinea and Sierra Leone, where plans for rolling out the malaria vaccine for children are being made. There is little evidence about caregiver acceptance rates to guide roll-out policies. To inform future vaccine implementation planning, this analysis aimed to assess potential malaria vaccine acceptance by caregivers and identify factors associated with acceptance in Guinea and Sierra Leone. METHODS: A cross-sectional household survey using lot quality assurance sampling was conducted in three regions per country between May 2022 and August 2022. The first survey respondent in each household provided sociodemographic information. A household member responsible for childcare shared their likelihood of accepting a malaria vaccine for their children under 5 years and details about children's health. The prevalence of caregiver vaccine acceptance was calculated and associated factors were explored using multivariable logistic regression modelling calculating adjusted odds ratios (aOR) with 95% confidence intervals (CI). RESULTS: Caregivers in 76% of 702 sampled households in Guinea and 81% of 575 households in Sierra Leone were accepting of a potential vaccine for their children. In both countries, acceptance was lower in remote areas than in urban areas (Guinea: aOR 0.22 [95%CI 0.09-0.50], Sierra Leone: 0.17 [0.06-0.47]). In Guinea, acceptance was lower among caregivers living in the richest households compared to the poorest households (0.10 [0.04-0.24]), among those whose children were tested for malaria when febrile (0.54 [0.34-0.85]) and in households adopting more preventative measures against malaria (0.39 [0.25-0.62]). Better knowledge of the cause of malaria infection was associated with increased acceptance (3.46 [1.01-11.87]). In Sierra Leone, vaccine acceptance was higher among caregivers living in households where the first respondent had higher levels of education as compared to lower levels (2.32 [1.05-5.11]). CONCLUSION: In both countries, malaria vaccine acceptance seems promising for future vaccine roll-out programmes. Policy makers might consider regional differences, sociodemographic factors, and levels of knowledge about malaria for optimization of implementation strategies. Raising awareness about the benefits of comprehensive malaria control efforts, including vaccination and other preventive measures, requires attention in upcoming campaigns.

Quantifying the value of viral genomics when inferring who infected whom in the 2014-16 Ebola virus outbreak in Guinea.

Transmission trees can be established through detailed contact histories, statistical or phylogenetic inference, or a combination of methods. Each approach has its limitations, and the extent to which they succeed in revealing a 'true' transmission history remains unclear. In this study, we compared the transmission trees obtained through contact tracing investigations and various inference methods to identify the contribution and value of each approach. We studied eighty-six sequenced cases reported in Guinea between March and November 2015. Contact tracing investigations classified these cases into eight independent transmission chains. We inferred the transmission history from the genetic sequences of the cases (phylogenetic approach), their onset date (epidemiological approach), and a combination of both (combined approach). The inferred transmission trees were then compared to those from the contact tracing investigations. Inference methods using individual data sources (i.e. the phylogenetic analysis and the epidemiological approach) were insufficiently informative to accurately reconstruct the transmission trees and the direction of transmission. The combined approach was able to identify a reduced pool of infectors for each case and highlight likely connections among chains classified as independent by the contact tracing investigations. Overall, the transmissions identified by the contact tracing investigations agreed with the evolutionary history of the viral genomes, even though some cases appeared to be misclassified. Therefore, collecting genetic sequences during outbreak is key to supplement the information contained in contact tracing investigations. Although none of the methods we used could identify one unique infector per case, the combined approach highlighted the added value of mixing epidemiological and genetic information to reconstruct who infected whom.

Determinants of Transmission Risk During the Late Stage of the West African Ebola Epidemic.

Understanding risk factors for Ebola transmission is key for effective prediction and design of interventions. We used data on 860 cases in 129 chains of transmission from the latter half of the 2013-2016 Ebola epidemic in Guinea. Using negative binomial regression, we determined characteristics associated with the number of secondary cases resulting from each infected individual. We found that attending an Ebola treatment unit was associated with a 38% decrease in secondary cases (incidence rate ratio (IRR) = 0.62, 95% confidence interval (CI): 0.38, 0.99) among individuals that did not survive. Unsafe burial was associated with a higher number of secondary cases (IRR = 1.82, 95% CI: 1.10, 3.02). The average number of secondary cases was higher for the first generation of a transmission chain (mean = 1.77) compared with subsequent generations (mean = 0.70). Children were least likely to transmit (IRR = 0.35, 95% CI: 0.21, 0.57) compared with adults, whereas older adults were associated with higher numbers of secondary cases. Men were less likely to transmit than women (IRR = 0.71, 95% CI: 0.55, 0.93). This detailed surveillance data set provided an invaluable insight into transmission routes and risks. Our analysis highlights the key role that age, receiving treatment, and safe burial played in the spread of EVD.

Public finances and tobacco taxation with product variety: Theory and application to Senegal and Nigeria.

This study endeavors to answer two questions: which category of excise taxes is more appropriate for Senegal and Nigeria and which consequences an increase of the tobacco taxes would have on the price, the demand and the tax revenues in each one of the two countries? To answer these questions, we adopt a double approach: first, a theoretical model of taxation with variety; and second, a simulation model to answer the second question. The results of the theoretical model indicate that, in the context of excise taxation, the number of products variety-or that of cigarette brands-directly affects both the degree of market concentration and the marginal effects of specific and ad valorem excise taxes on the price of tobacco. In addition, the comparison of the marginal effects of ad valorem and specific excise taxes depends on the marginal costs of production of different varieties weighted by the tax rates and the number of varieties. Our empirical results first show that the specific excise taxes are more adapted to Senegal while ad valorem excise taxes fit best Nigeria. This result crucially matters for the excise taxes are exclusively of an ad valorem nature in both Senegal and Nigeria. It is perfectly possible to envisage a situation where the two main forms of excise taxes could co-exist. It also appears from our results that tax development does not have the same implications for the two countries. Increasing tobacco taxes in Senegal strongly reduces the demand, but also induces a decrease in the tax revenues, while this will imply a lesser decline in demand in Nigeria accompanied however by a sharp increase of the country's tax revenues. This difference stems from the fact that the price-elasticity of tobacco demand is very high in Senegal, contrary to Nigeria. Finally, it is important to mention that there is a specific threshold beyond which the tax increases cease to have a positive effect on tax revenues in Nigeria.

Prescriber practices and patient adherence to artemisinin-based combination therapy for the treatment of uncomplicated malaria in Guinea, 2016.

BACKGROUND: The World Health Organization recommends the use of artemisinin-based combination therapy (ACT) to treat uncomplicated malaria for the control of malaria across the world. There are several types of ACT used across malaria-endemic countries, yet there is little information about preferences and adherence practices regarding different types of ACT. The objective of this study was to evaluate levels of adherence to two types of ACT, artemether-lumefantrine (AL) and artesunate + amodiaquine (ASAQ), for the treatment of uncomplicated malaria among prescribers and patients in Guinea in 2016. METHODS: The study included a review of records of malaria patients and three health-facility, cross-sectional surveys. Patients diagnosed with uncomplicated malaria and prescribed ACT (n = 1830) were recruited and visited in their home after receiving the medication and administered a questionnaire regarding ACT adherence. Prescribers (n = 115) and drug dispensers (n = 43) were recruited at the same public health facilities and administered questionnaires regarding prescribing practices and opinions regarding the national treatment policies and protocols. RESULTS: According to the registry review, 35.8% of all-cause consultations were recorded as malaria. Of these, 26.6% were diagnosed clinically without documentation of laboratory confirmation. The diagnosis of uncomplicated malaria represented 64.1% of malaria cases among children under 5 years and 74.9% of those 5 years of age and older. An ACT was prescribed for 83.5% of cases of uncomplicated malaria. Among participants in the study, ACT adherence was 95.4% (95% CI 94.4, 96.3). Overall, about one in four patients (23.4%; 95% CI 21.5, 25.3) reported experiencing adverse events. While patients prescribed ASAQ were significantly more likely to report experiencing adverse effects than patients on AL (p < 0.001), given the overall high adherence, there was no evidence of a statistically significant difference in adherence between AL and ASAQ. Patients 5 years or older who reported experiencing adverse events were more likely to be non-adherent. CONCLUSION: Although there were more reported adverse events associated with ASAQ when compared with AL, both prescribers and patients were found to be mostly adherent to ACT for the treatment of malaria, regardless of ACT type.

Rapid Epidemiological and Entomological Survey for Validation of Reported Indicators and Characterization of Local Malaria Transmission in Guinea, 2017.

To confirm and investigate possible explanations for unusual trends in malaria indicators, a protocol for rapid, focal assessment of malaria transmission and control interventions was piloted in N'Zérékoré and Macenta Prefectures, which each reported surprisingly low incidence of malaria during the peak transmission months during 2017 in holoendemic Forested Guinea. In each prefecture, epidemiological and entomological cross-sectional surveys were conducted in two sub-prefectures reporting high incidence and one sub-prefecture reporting low incidence. Investigators visited six health facilities and 356 households, tested 476 children, performed 14 larval breeding site transects, and conducted 12 nights of human landing catches during the 2-week investigation. Rapid diagnostic test positivity in the community sample of children under five ranged from 23% to 68% by subprefecture. Only 38% of persons with fever reported seeking care in the public health sector; underutilization was confirmed by verification of health facility and community healthcare worker (CHW) registries. High numbers of Anopheles mosquitoes were collected in human landing collections in N'Zérékoré (38 per night in combined indoor and outdoor collections) and Macenta (87). Most of the detected breeding sites positive for Anopheles larvae (83%) were shallow roadside puddles. In the investigated prefectures, malaria rates remain high and the low reported incidence likely reflects low utilization of the public health-care sector. Strengthening the CHW program to rapidly identify and treat malaria cases and elimination of roadside puddles as part of routine cleanup campaigns should be considered. Systematic joint epidemiological/entomological investigations in areas reporting anomalous signals in routine data can allow control programs to respond with tailored local interventions.

Interferon ß-1a for the treatment of Ebola virus disease: A historically controlled, single-arm proof-of-concept trial.

To date there are no approved antiviral drugs for the treatment of Ebola virus disease (EVD). Based on our in vitro evidence of antiviral activity of interferon (IFN)-ß activity against Ebola virus, we conducted a single arm clinical study in Guinea to evaluate the safety and therapeutic efficacy of IFN ß-1a treatment for EVD. Nine individuals infected with Ebola virus were treated with IFN ß-1a and compared retrospectively with a matched cohort of 21 infected patients receiving standardized supportive care only during the same time period at the same treatment unit. Cognizant of the limitations of having treated only 9 individuals with EVD, the data collected are cautiously considered. When compared to supportive care only, IFN ß-1a treatment seemed to facilitate viral clearance from the blood and appeared associated with earlier resolution of disease symptoms. Survival, calculated from the date of consent for those in the trial and date of admission from those in the control cohort, to the date of death, was 19% for those receiving supportive care only, compared to 67% for those receiving supportive care plus IFN ß-1a. Given the differences in baseline blood viremia between the control cohort and the IFN-treated cohort, an additional 17 controls were included for a subset analysis, from other treatment units in Guinea, matched with the IFN-treated patients based on age and baseline blood viremia. Subset analyses using this expanded control cohort suggests that patients without IFN ß-1a treatment were ~ 1.5-1.9 fold more likely to die than those treated. Viewed altogether the results suggest a rationale for further clinical evaluation of IFN ß-1a.