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•The GMZ2 fusion protein consist of the non-repeat region of falciparum GLURP genetically fused to a msp3 fragment.•The GMZ2 fusion protein elicited functional antibodies in phase 1 studies.•In the ATP analysis, vaccine efficacy adjusted for age and site was 14% (95% CI: 3.6%, 23%).•Vaccine efficacy was higher in older children.•In GMZ2-vaccinated children, the incidence of malaria decreased with increasing vaccine-induced anti-GMZ2 IgG concentration. GMZ2 is a recombinant protein malaria vaccine, comprising two blood-stage antigens of Plasmodium falciparum, glutamate-rich protein and merozoite surface protein 3. We assessed efficacy of GMZ2 in children in Burkina Faso, Gabon, Ghana and Uganda. Children 12–60months old were randomized to receive three injections of either 100μg GMZ2 adjuvanted with aluminum hydroxide or a control vaccine (rabies) four weeks apart and were followed up for six months to measure the incidence of malaria defined as fever or history of fever and a parasite density ⩾5000/μL. A cohort of 1849 children were randomized, 1735 received three doses of vaccine (868 GMZ2, 867 control-vaccine). There were 641 malaria episodes in the GMZ2/Alum group and 720 in the control group. In the ATP analysis, vaccine efficacy (VE), adjusted for age and site was 14% (95% confidence interval [CI]: 3.6%, 23%, p-value=0.009). In the ITT analysis, age-adjusted VE was 11.3% (95% CI 2.5%, 19%, p-value=0.013). VE was higher in older children. In GMZ2-vaccinated children, the incidence of malaria decreased with increasing vaccine-induced anti-GMZ2 IgG concentration. There were 32 cases of severe malaria (18 in the rabies vaccine group and 14 in the GMZ2 group), VE 27% (95% CI −44%, 63%). GMZ2 is the first blood-stage malaria vaccine to be evaluated in a large multicenter trial. GMZ2 was well tolerated and immunogenic, and reduced the incidence of malaria, but efficacy would need to be substantially improved, using a more immunogenic formulation, for the vaccine to have a public health role.

Background Malaria remains a major public health problem, especially among children in sub-Saharan Africa. Knowledge of malaria parasite prevalence informs targeted interventions and helps to monitor the effectiveness of those interventions. This study aimed to determine prevalence and factors associated with malaria in children aged 6 months to 10 years in the Greater Accra Region of Ghana. Methods A community-based cross-sectional study was conducted among 8,741 children aged 6–59 months and 8,292 children aged 5–10 years in all 29 districts of the Greater Accra Region of Ghana in October 2020. Systematic random sampling was used to select communities, households and study participants. A structured questionnaire was used to collect data from caregivers. Rapid diagnostic test kits were used to determine the presence of malaria parasites in blood samples collected by fingerprick. Factors associated with malaria RDT-positivity were determined using multivariate logistic regression analysis. Results Of 8727 children aged 6–59 months and 8279 aged 5–10 years from whom blood samples were obtained, positive results were obtained for 289 (3.3%; 95% CI 3.0–3.7) and 406 (4.9%; 95% CI 4.5–5.4) respectively. Malaria parasite prevalence in the districts ranged from 0.9 to 10.7% and 1.4–15.0% in children aged 6–59 months and 5–10 years respectively. Factors associated with increased odds of malaria included higher age (AOR = 1.43; 95% CI 1.14–1.71), and living in households without nets on the windows (AOR 1.64; 95% CI 1.10–2.45). On the other hand, living in households located in urban communities was associated with a lower risk of malaria (AOR 0.56; 95% CI 0.40–0.78). Conclusion The average prevalence of malaria in the Greater Accra Region is low compared with other regions. However, there are potential hotspots that need to be targeted with appropriate interventions to accelerate the drive towards malaria elimination.

Background Accurate measurement of anti-malarial drug concentrations in therapeutic efficacy studies is essential to distinguish between inadequate drug exposure and anti-malarial drug resistance, and to inform optimal anti-malarial dosing in key target population groups. Methods A sensitive and selective LC–MS/MS method was developed and validated for the simultaneous determination of amodiaquine and its active metabolite, desethylamodiaquine, and used to describe their pharmacokinetic parameters in Ghanaian patients with uncomplicated falciparum malaria treated with the fixed-dose combination, artesunate-amodiaquine. Results The day-28 genotype-adjusted adequate clinical and parasitological response rate in 308 patients studied was > 97% by both intention-to-treat and per-protocol analysis. After excluding 64 patients with quantifiable amodiaquine concentrations pre-treatment and 17 with too few quantifiable concentrations, the pharmacokinetic analysis included 227 patients (9 infants, 127 aged 1–4 years, 91 aged ≥ 5 years). Increased median day-3 amodiaquine concentrations were associated with a lower risk of treatment failure [HR 0.87 (95% CI 0.78–0.98), p = 0.021]. Amodiaquine exposure (median AUC 0-∞ ) was significantly higher in infants (4201 ng h/mL) and children aged 1–5 years (1994 ng h/mL) compared to older children and adults (875 ng h/mL, p = 0.001), even though infants received a lower mg/kg amodiaquine dose (median 25.3 versus 33.8 mg/kg in older patients). Desethylamodiaquine AUC 0-∞ was not significantly associated with age. No significant safety concerns were identified. Conclusions Efficacy of artesunate-amodiaquine at currently recommended dosage regimens was high across all age groups. Reassuringly, amodiaquine and desethylamodiaquine exposure was not reduced in underweight-for-age young children or those with high parasitaemia, two of the most vulnerable target populations. A larger pharmacokinetic study with close monitoring of safety, including full blood counts and liver function tests, is needed to confirm the higher amodiaquine exposure in infants, understand any safety implications and assess whether dose optimization in this vulnerable, understudied population is needed.

Plasmodium falciparum induced antibodies are key components of anti-malarial immunity in malaria endemic areas, but their antigen targets can be polymorphic. Induction of a high proportion of strain-specific antibodies will limit the recognition of a broad diversity of parasite strains by these responses. There are indications that circulating parasite diversity varies with malaria transmission intensity, and this may affect the specificity of elicited anti-malarial antibodies. This study therefore assessed the effect of varying malaria transmission patterns on the specificity of elicited antibody responses and to identify possible antibody correlates of naturally acquired immunity to malaria in children in an area of Ghana with seasonal malaria transmission. This retrospective study utilized plasma samples collected longitudinally at six time points from children aged one to five years. Multiplex assays were used to measure antibody levels against four P. falciparum AMA 1 variants (from the 3D7, FVO, HB3 and CAMP parasite strains) and the 3D7 variant of the EBA 175 region II antigen and the levels compared between symptomatic and asymptomatic children. The relative proportions of cross-reactive and strain-specific antibodies against the four AMA 1 variants per sampling time point were assessed by Bland-Altman plots. The levels of antibodies against allelic AMA1 variants, measured by singleplex and multiplex luminex assays, were also compared. The data show that increased transmission intensity is associated with higher levels of cross-reactive antibody responses, most likely a result of a greater proportion of multiple parasite clone infections during the high transmission period. Anti-AMA1 antibodies were however associated with a history of infection rather than protection in this age group. The data contribute to understanding the underlying mechanism of the acquisition of strain-transcending antibody immunity following repeated exposure to diverse parasite strains.

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Background Considering the natural history of malaria of continued susceptibility to infection and episodes of illness that decline in frequency and severity over time, studies which attempt to relate immune response to protection must be longitudinal and have clearly specified definitions of immune status. Putative vaccines are expected to protect against infection, mild or severe disease or reduce transmission, but so far it has not been easy to clearly establish what constitutes protective immunity or how this develops naturally, especially among the affected target groups. The present study was done in under six year old children to identify malaria antigens which induce antibodies that correlate with protection from Plasmodium falciparum malaria. Methods In this longitudinal study, the multiplex assay was used to measure IgG antibody levels to 10 malaria antigens (GLURP R0, GLURP R2, MSP3 FVO, AMA1 FVO, AMA1 LR32, AMA1 3D7, MSP1 3D7, MSP1 FVO, LSA-1and EBA175RII) in 325 children aged 1 to 6 years in the Kassena Nankana district of northern Ghana. The antigen specific antibody levels were then related to the risk of clinical malaria over the ensuing year using a negative binomial regression model. Results IgG levels generally increased with age. The risk of clinical malaria decreased with increasing antibody levels. Except for FMPOII-LSA, (p = 0.05), higher IgG levels were associated with reduced risk of clinical malaria (defined as axillary temperature ≥37.5°C and parasitaemia of ≥5000 parasites/ul blood) in a univariate analysis, upon correcting for the confounding effect of age. However, in a combined multiple regression analysis, only IgG levels to MSP1-3D7 (Incidence rate ratio = 0.84, [95% C.I.= 0.73, 0.97, P = 0.02]) and AMA1 3D7 (IRR = 0.84 [95% C.I.= 0.74, 0.96, P = 0.01]) were associated with a reduced risk of clinical malaria over one year of morbidity surveillance. Conclusion The data from this study support the view that a multivalent vaccine involving different antigens is most likely to be more effective than a monovalent one. Functional assays, like the parasite growth inhibition assay will be necessary to confirm if these associations reflect functional roles of antibodies to MSP1-3D7 and AMA1-3D7 in this population.

The Government of Ghana introduced the National Health Insurance Scheme (NHIS) in 2003 to replace out-of-pocket (OOP) payment for health services with the inherent aim of reducing the direct cost of treating illness to households. To assess the effects of the NHIS in reducing cost of treating malaria to households in the Kassena-Nankana districts of northern Ghana. We conducted a cross-sectional survey between October 2009 and October 2011 in the Kassena-Nankana districts. A sample of 4,226 households was randomly drawn from the Navrongo Health and Demographic Surveillance System household database and administered a structured interview. The costs of malaria treatment were collected from the patient perspective. Of the 4,226 households visited, a total of 1,324 (31%) household members reported fever and 51% (675) reported treatment for malaria and provided information on where they sought care. Most respondents sought malaria treatment from formal health facilities 63% (424), with the remainder either self-medicating with drugs from chemical shops 32% (217) or with leftover drugs or herbs 5% (34). Most of those who sought care from formal health facilities were insured 79% (334). The average direct medical cost of treating malaria was GH¢3.2 (US$2.1) per case with the insured spending less (GH¢2.6/US$1.7) per case than the uninsured (GH¢3.2/US$2.1). The overall average cost (direct and indirect) incurred by households per malaria treatment was GH¢20.9 (US$13.9). Though the insured accounted for a larger proportion of admissions at health facilities 76% (31) than the uninsured 24% (10), the average amount households spent on the insured was less (GH¢4/US$2.7) than their uninsured counterparts (GH¢6.4/US$4.3). The difference was not statistically significant (p=0.2330). Even though some insured individuals made OOP payments for direct medical care, there is evidence that the NHIS has a protective effect on cost (outpatient and in-patient) of malaria treatment.

While live oral rotavirus vaccines (LORVs) are effective at preventing severe rotavirus gastroenteritis (SRVGE), they perform sub-optimally in the settings with the highest burden. Parenteral rotavirus vaccines could have greater efficacy by bypassing the gut, where interference with LORVs may occur. A novel parenteral rotavirus subunit vaccine (TV P2-VP8) was evaluated in a Phase 3 study for safety, immunogenicity, and relative efficacy in healthy African infants. Participating infants were randomized at 6–8 weeks of age to receive either three doses of TV P2-VP8 intramuscularly (IM) plus oral placebo or two doses of ROTARIX® (oral) plus IM placebo. The trial was designed to enroll a total of 8200 participants in two stages separated by an interim analysis conducted upon accrual of a predetermined number of SRVGE cases. Data at interim analysis indicated a low probability of demonstrating TV P2-VP8 superiority compared to ROTARIX in prevention of SRVGE, and the study was closed early. 4055 infants were enrolled and provided safety data. TV P2-VP8 was safe and well tolerated, with no safety concerns indicated. Virus neutralizing and IgG binding antibody seroresponses to TV-P2-VP8 were detected in most participants. The crude attack rates of SRVGE in the per-protocol population (n = 3477) were 4.51 % (TV P2-VP8) and 2.57 % (ROTARIX). The relative vaccine efficacy (RVE) against SRVGE for TV P2-VP8 was −77.68 % (95 % CI, −162.38, −21.54). The RVE against SRVGE in the first and second year of life was −91.67 % (95 % CI, −199.20, −24.35) and − 31.97 % (95 % CI, −220.37, 44.49), respectively. The RVE against rotavirus gastroenteritis of any severity was −47.78 % (95 % CI, −89.63, −15.59). TV P2-VP8 provided inferior protection against SRVGE compared to ROTARIX. The vaccine candidate was safe, immunogenic, and well-tolerated by infants. Continued efforts are needed to identify alternative rotavirus vaccines with improved efficacy in LMICs. Trial Registration:NCT04010448; PACTR201907491834482. •The TV P2-VP8 vaccine candidate was safe and immunogenic.•Three doses of TV P2-VP8 were inferior to two doses of ROTARIX® in preventing severe rotavirus gastroenteritis.•Study provides insight to guide future development of rotavirus vaccine candidates.

The GMZ2/alum candidate malaria vaccine had an efficacy of 14% (95% confidence interval [CI]: 3.6%, 23%) against clinical malaria over 6 months of follow-up in a phase2b multicentre trial in children 1–5 years of age. Here we report the extended follow up of safety and efficacy over 2 years. A total of 1849 (GMZ2 = 926, rabies = 923) children aged 12–60 months were randomized to receive intramuscularly, either 3 doses of 100 μg GMZ2/alum or 3 doses of rabies vaccine as control 28 days apart. The children were followed-up for 24 months for clinical malaria episodes and adverse events. The primary endpoint was documented fever with parasitaemia of at least 5000/μL. There were 2,062 malaria episodes in the GMZ2/alum group and 2,115 in the rabies vaccine group in the intention-to-treat analysis, vaccine efficacy (VE) of 6.5% (95%: CI −1.6%, 14.0%). In children aged 1–2 years at enrolment, VE was 3.6% (95 %CI: −9.1%, 14.8%) in the first year and −4.1% (95 %CI: −18.7%, 87%) in the second year. In children aged 3–5 years at enrolment VE was 19.9% (95 %CI: 7.7%, 30.4%) in the first year and 6.3% (95 %CI: −10.2%, 20.3%) in the second year (interaction by year, P = 0.025, and by age group, P = 0.085). A total of 187 (GMZ2 = 91, rabies = 96) serious adverse events were recorded in 167 individuals over the entire period of the study. There were no GMZ2 vaccine related serious adverse events. GMZ2/alum was well tolerated. Follow-up over 2 years confirmed a low level of vaccine efficacy with slightly higher efficacy in older children, which suggests GMZ2 may act in concert with naturally acquired immunity.

Background Malaria control interventions have led to a decline in transmission intensity in many endemic areas, and resulted in elimination in some areas. This decline, however, will lead to delayed acquisition of protective immunity and thus impact disease manifestation and outcomes. Therefore, the variation in clinical and haematological parameters in children with malaria was assessed across three areas in Ghana with varying transmission intensities. Methods A total of 568 children between the ages of 2 and 14 years with confirmed malaria were recruited in hospitals in three areas with varying transmission intensities (Kintampo > Navrongo > Accra) and a comprehensive analysis of parasitological, clinical, haematological and socio-economic parameters was performed. Results Areas of lower malaria transmission tended to have lower disease severity in children with malaria, characterized by lower parasitaemias and higher haemoglobin levels. In addition, total white cell counts and percent lymphocytes decreased with decreasing transmission intensity. The heterozygous sickle haemoglobin genotype was protective against disease severity in Kintampo ( P  = 0.016), although this was not significant in Accra and Navrongo. Parasitaemia levels were not a significant predictor of haemoglobin level after controlling for age and gender. However, higher haemoglobin levels in children were associated with certain socioeconomic factors, such as having fathers who had any type of employment ( P  < 0.05) and mothers who were teachers ( P  < 0.05). Conclusions The findings demonstrate significant differences in the haematological presentation and severity of malaria among areas with different transmission intensity in Ghana, indicating that these factors need to be considered in planning the management of the disease as the endemicity is expected to decline after control interventions.