Seasonal vaccination with RTS,S/AS01E vaccine with or without seasonal malaria chemoprevention in children up to the age of 5 years in Burkina Faso and Mali: a double-blind, randomised, controlled, phase 3 trial

BACKGROUND

Seasonal vaccination with the RTS,S/AS01E vaccine combined with seasonal malaria chemoprevention (SMC) prevented malaria in young children more effectively than either intervention given alone over a 3 year period. The objective of this study was to establish whether the added protection provided by the combination could be sustained for a further 2 years.

METHODS

This was a double-blind, individually randomised, controlled, non-inferiority and superiority, phase 3 trial done at two sites: the Bougouni district and neighbouring areas in Mali and Houndé district, Burkina Faso. Children who had been enrolled in the initial 3-year trial when aged 5-17 months were initially randomly assigned individually to receive SMC with sulphadoxine-pyrimethamine and amodiaquine plus control vaccines, RTS,S/AS01E plus placebo SMC, or SMC plus RTS,S/AS01E. They continued to receive the same interventions until the age of 5 years. The primary trial endpoint was the incidence of clinical malaria over the 5-year trial period in both the modified intention-to-treat and per-protocol populations. Over the 5-year period, non-inferiority was defined as a 20% increase in clinical malaria in the RTS,S/AS01E-alone group compared with the SMC alone group. Superiority was defined as a 12% difference in the incidence of clinical malaria between the combined and single intervention groups. The study is registered with ClinicalTrials.gov, NCT04319380, and is complete.

FINDINGS

In April, 2020, of 6861 children originally recruited, 5098 (94%) of the 5433 children who completed the initial 3-year follow-up were re-enrolled in the extension study. Over 5 years, the incidence of clinical malaria per 1000 person-years at risk was 313 in the SMC alone group, 320 in the RTS,S/AS01E-alone group, and 133 in the combined group. The combination of RTS,S/AS01E and SMC was superior to SMC (protective efficacy 57·7%, 95% CI 53·3 to 61·7) and to RTS,S/AS01E (protective efficacy 59·0%, 54·7 to 62·8) in preventing clinical malaria. RTS,S/AS01E was non-inferior to SMC (hazard ratio 1·03 [95% CI 0·95 to 1·12]). The protective efficacy of the combination versus SMC over the 5-year period of the study was very similar to that seen in the first 3 years with the protective efficacy of the combination versus SMC being 57·7% (53·3 to 61·7) and versus RTS/AS01E-alone being 59·0% (54·7 to 62·8). The comparable figures for the first 3 years of the study were 62·8% (58·4 to 66·8) and 59·6% (54·7 to 64·0%), respectively. Hospital admissions for WHO-defined severe malaria were reduced by 66·8% (95% CI 40·3 to 81·5), for malarial anaemia by 65·9% (34·1 to 82·4), for blood transfusion by 68·1% (32·6 to 84·9), for all-cause deaths by 44·5% (2·8 to 68·3), for deaths excluding external causes or surgery by 41·1% (-9·2 to 68·3), and for deaths from malaria by 66·8% (-2·7 to 89·3) in the combined group compared with the SMC alone group. No safety signals were detected.

INTERPRETATION

Substantial protection against malaria was sustained over 5 years by combining seasonal malaria vaccination with seasonal chemoprevention, offering a potential new approach to malaria control in areas with seasonal malaria transmission.

FUNDING

UK Joint Global Health Trials and PATH's Malaria Vaccine Initiative (through a grant from the Bill & Melinda Gates Foundation).

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

The duration of protection against clinical malaria provided by the combination of seasonal RTS,S/AS01E vaccination and seasonal malaria chemoprevention versus either intervention given alone

BACKGROUND

A recent trial of 5920 children in Burkina Faso and Mali showed that the combination of seasonal vaccination with the RTS,S/AS01E malaria vaccine (primary series and two seasonal boosters) and seasonal malaria chemoprevention (four monthly cycles per year) was markedly more effective than either intervention given alone in preventing clinical malaria, severe malaria, and deaths from malaria.

METHODS

In order to help optimise the timing of these two interventions, trial data were reanalysed to estimate the duration of protection against clinical malaria provided by RTS,S/AS01E when deployed seasonally, by comparing the group who received the combination of SMC and RTS,S/AS01E with the group who received SMC alone. The duration of protection from SMC was also estimated comparing the combined intervention group with the group who received RTS,S/AS01E alone. Three methods were used: Piecewise Cox regression, Flexible parametric survival models and Smoothed Schoenfeld residuals from Cox models, stratifying on the study area and using robust standard errors to control for within-child clustering of multiple episodes.

RESULTS

The overall protective efficacy from RTS,S/AS01E over 6 months was at least 60% following the primary series and the two seasonal booster doses and remained at a high level over the full malaria transmission season. Beyond 6 months, protective efficacy appeared to wane more rapidly, but the uncertainty around the estimates increases due to the lower number of cases during this period (coinciding with the onset of the dry season). Protection from SMC exceeded 90% in the first 2-3 weeks post-administration after several cycles, but was not 100%, even immediately post-administration. Efficacy begins to decline from approximately day 21 and then declines more sharply after day 28, indicating the importance of preserving the delivery interval for SMC cycles at a maximum of four weeks.

CONCLUSIONS

The efficacy of both interventions was highest immediately post-administration. Understanding differences between these interventions in their peak efficacy and how rapidly efficacy declines over time will help to optimise the scheduling of SMC, malaria vaccination and the combination in areas of seasonal transmission with differing epidemiology, and using different vaccine delivery systems.

TRIAL REGISTRATION

The RTS,S-SMC trial in which these data were collected was registered at clinicaltrials.gov: NCT03143218.

Malaria infection is common and associated with perinatal mortality and preterm delivery despite widespread use of chemoprevention in Mali: an observational study 2010 to 2014

BACKGROUND

In malaria-endemic areas, pregnant women and especially first-time mothers are more susceptible to Plasmodium falciparum. Malaria diagnosis is often missed during pregnancy, since many women with placental malaria remain asymptomatic or have submicroscopic parasitemia, masking the association between malaria and pregnancy outcomes Severe maternal anemia and low birthweight deliveries are well-established sequelae, but few studies have confirmed the relationship between malaria infection and severe outcomes like perinatal mortality in high transmission zones.

METHODS

Pregnant women of any gestational age enrolled at antenatal clinic into a longitudinal cohort study in Ouelessebougou, Mali, an area of high seasonal malaria transmission. Follow-up visits included scheduled and unscheduled visits throughout pregnancy. Blood smear microscopy and PCR analysis were employed to detect both microscopic and submicroscopic infections, respectively. Intermittent preventative treatment in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) was documented and prompt treatment regardless of symptoms given upon malaria diagnosis.

RESULTS

Of the 1850 women followed through delivery, 72.6% of women received 2 or more IPTp-SP doses, 67.2% of women experienced at least one infection between enrollment up to and including delivery. Malaria infection increased the risks of stillbirth (adjusted-hazard ratio (aHR) 3.87, 95%CI 1.18-12.71) and preterm delivery (aHR 2.41, 95%CI 1.35-4.29) in primigravidae, and early neonatal death (death within 7 days) in secundigravidae and multigravidae (HR 6.30, 95%CI 1.41-28.15).

CONCLUSIONS

Malaria treatment after diagnosis, alongside IPTp-SP, is insufficient to prevent malaria-related stillbirth, early neonatal death and PTD. While IPTp-SP was beneficial in Mali during the study period, new tools are needed to improve pregnancy outcomes.

Systemic Inflammatory Response to Malaria During Pregnancy Is Associated With Pregnancy Loss and Preterm Delivery

Background

Pregnancy malaria (PM) is associated with a proinflammatory immune response characterized by increased levels of cytokines and chemokines such as tumor necrosis factor-α, interferon-γ, interleukin 10 (IL-10), and CXCL9. These changes are associated with poor outcomes including low birthweight delivery and maternal anemia. However, it is unknown if inflammatory pathways during malaria are related to pregnancy loss and preterm delivery (PTD).

Methods

Cytokine and chemokine levels were measured in maternal peripheral blood at enrollment, gestational week 30-32, and delivery, and in placental blood, of 638 women during a longitudinal cohort study in Ouelessebougou, Mali. Plasmodium falciparum infection was assessed by blood smear microscopy at all visits.

Results

PM was associated with increased levels of cytokines and chemokines including IL-10 and CXCL9. In a competing risks model adjusted for known covariates, high CXCL9 levels measured in the peripheral blood during pregnancy were associated with increased risk of pregnancy loss and PTD. At delivery, high IL-10 levels in maternal blood were associated with an increase in pregnancy loss, and increased IL-1β levels in placental blood were associated with pregnancy loss and PTD.

Conclusions

PM is associated with increased proinflammatory cytokine and chemokine levels in placental and maternal peripheral blood. Systemic inflammatory responses to malaria during pregnancy predict increased risk of pregnancy loss and PTD.

Clinical Trials Registration

NCT01168271.

Antibody levels to recombinant VAR2CSA domains vary with Plasmodium falciparum parasitaemia, gestational age, and gravidity, but do not predict pregnancy outcomes

Background

Maternal malaria is a tropical scourge associated with poor pregnancy outcomes. Women become resistant to Plasmodium falciparum pregnancy malaria as they acquire antibodies to the variant surface antigen VAR2CSA, a leading vaccine candidate. Because malaria infection may increase VAR2CSA antibody levels and thereby confound analyses of immune protection, gravidity-dependent changes in antibody levels during and after infection, and the effect of VAR2CSA antibodies on pregnancy outcomes were evaluated.

Methods

Pregnant women enrolled in a longitudinal cohort study of mother-infant pairs in Ouelessebougou, Mali provided plasma samples at enrollment, gestational week 30–32, and delivery. Antibody levels to VAR2CSA domains were measured using a multiplex bead-based assay.

Results

Antibody levels to VAR2CSA were higher in multigravidae than primigravidae. Malaria infection was associated with increased antibody levels to VAR2CSA domains. In primigravidae but not in secundigravidae or multigravidae, antibodies levels sharply declined after an infection. A relationship between any VAR2CSA antibody specificity and protection from adverse pregnancy outcomes was not detected.

Conclusions

During malaria infection, primigravidae acquire short-lived antibodies. The lack of an association between VAR2CSA domain antibody reactivity and improved pregnancy outcomes suggests that the recombinant proteins may not present native epitopes targeted by protective antibodies.

Electronic supplementary material

The online version of this article (10.1186/s12936-018-2258-9) contains supplementary material, which is available to authorized users.

Safety, reactogenicity and immunogenicity of 2-dose catch-up vaccination with 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Malian children in the second year of life: Results from an open study

Pneumonia is still the leading cause of death among African children with pneumococcal serotypes 1 and 5 being dominant in the below 5 y of age group. The present study assessed the safety, reactogenicity and immunogenicity of a 2-dose catch-up vaccination with the 10-valent pneumococcal non-typeable Haemophilus influenzae Protein D conjugate vaccine (PHiD-CV) in Malian children. This phase III, open-label study (NCT00985465) was conducted in Ouelessebougou, Mali, between November 2009 and July 2010. The study population consisted of PHiD-CV unprimed Malian children previously enrolled in the control group of study NCT00678301 receiving a 2-dose catch-up vaccination with PHiD-CV in the second year of life. Adverse events were recorded following each PHiD-CV dose. Antibody responses and opsonophagocytic activity (OPA) were measured pre-vaccination and after the second PHiD-CV catch-up dose. Swelling and fever (axillary temperature ≥ 37.5°C) were the most frequently reported solicited symptoms following either PHiD-CV dose. Few grade 3 solicited symptoms were reported. Large swelling reactions and serious adverse events were not reported. Post-catch-up vaccination, for each vaccine pneumococcal serotype, at least 94.7% of subjects had antibody concentrations ≥ 0.2 μg/ml, except for serotypes 6B (82.5%) and 23F (87.7%). At least 94.0% of subjects had OPA titres ≥ 8, except for serotype 19F (89.4%). The geometric mean concentration for antibodies against protein D was 839.3 (95% CI: 643.5-1094.6) EL.U/ml. Two-dose PHiD-CV catch-up regimen in the second year of life was well-tolerated and immunogenic for all vaccine pneumococcal serotypes and NTHi protein D when administered to Malian children

Safety, reactogenicity and immunogenicity of a booster dose of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Malian children

BACKGROUND

Primary vaccination with the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) was previously shown to be immunogenic and well tolerated in Malian children. Data on booster vaccination with a fourth consecutive dose of PHiD-CV are available for Europe, Asia and Latin America but are lacking for Africa. The present study evaluated further the safety, reactogenicity and immunogenicity of a fourth consecutive (booster) dose of PHiD-CV.

RESULTS

Low incidences of AEs with grade 3 intensity (2.1% of subjects) were observed. There were no reports of large swelling reactions and serious adverse events. One month post-booster vaccination, for each vaccine pneumococcal serotype, at least 97.8% of subjects had antibody concentrations ≥ 0.2 μg/ml, and at least 97.1% of subjects had opsonophagocytic activity ≥ 8. From pre- to post-booster, a 12.3-fold increase in anti-protein D geometric mean concentration was observed.

METHODS

This phase III, open-label study was conducted in Ouelessebougou, Mali, between November 2009 and June 2010. The study population consisted of Malian children previously primed (3 doses) with PHiD-CV in study NCT00678301 receiving a fourth consecutive (booster) dose of PHiD-CV in the second year of life. The incidences of adverse events (AEs) with grade 3 intensity (primary objective) or of any intensity (secondary objective), and the immunogenicity (secondary objective) of the PHiD-CV booster dose were assessed.

CONCLUSION

A booster dose of PHiD-CV was well tolerated when administered to Malian children in the second year of life and was highly immunogenic for all 10 vaccine pneumococcal serotypes and NTHi protein D. (ClinicalTrials.gov identifier: NCT00985465).

Malaria morbidity in children in the year after they had received intermittent preventive treatment of malaria in Mali: a randomized control trial

BACKGROUND

Intermittent preventive treatment of malaria in children (IPTc) is a promising strategy for malaria control. A study conducted in Mali in 2008 showed that administration of three courses of IPTc with sulphadoxine-pyrimethamine (SP) and amodiaquine (AQ) at monthly intervals reduced clinical malaria, severe malaria and malaria infection by >80% in children under 5 years of age. Here we report the results of a follow-on study undertaken to establish whether children who had received IPTc would be at increased risk of malaria during the subsequent malaria transmission season.

METHODS

Morbidity from malaria and the prevalence of malaria parasitaemia and anaemia were measured in children who had previously received IPTc with SP and AQ using similar surveillance methods to those employed during the previous intervention period.

RESULTS

1396 of 1508 children (93%) who had previously received IPTc and 1406 of 1508 children (93%) who had previously received placebos were followed up during the high malaria transmission season of the year following the intervention. Incidence rates of clinical malaria during the post-intervention transmission season (July-November 2009) were 1.87 (95% CI 1.76-1.99) and 1.73 (95% CI; 1.62-1.85) episodes per child year in the previous intervention and placebo groups respectively; incidence rate ratio (IRR) 1.09 (95% CI 0.99-1.21) (P = 0.08). The prevalence of malaria infection was similar in the two groups, 7.4% versus 7.5%, prevalence ratio (PR) of 0.99 (95% CI 0.73-1.33) (P = 0.95). At the end of post-intervention malaria transmission season, the prevalence of anaemia, defined as a haemoglobin concentration<11g/dL, was similar in the two groups (56.2% versus 55.6%; PR = 1.01 [95% CI 0.91-1.12]) (P = 0.84).

CONCLUSION

IPTc with SP+AQ was not associated with an increase in incidence of malaria episodes, prevalence of malaria infection or anaemia in the subsequent malaria transmission season.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00738946.

Growth of adolescents in Mali (West Africa)

This report describes the growth curve during adolescence in the rural area of Mali (West Africa). The authors measured the height, weight, and arm circumference in a sample of 1255 subjects over 14 years and below 20 years of age during a 2-year cross-sectional study (1984-1985). The comparison of the trend of these criteria with French data suggests that Malian adolescents present a different growth curve to those observed in industralized countries.

Lack of secular change in male adult stature in rural Mali (West Africa)

A study has been carried out on a sample of 2,158 male subjects between 20 and 50 years old representative of the rural Malian population (West Africa), and the results are compared with historic data obtained since 1885. This comparison suggests that there has been no modification in stature during this century. The analysis of each ethnic group does not show any disparity. Our results are in agreement with the theory that certain factors lead to the secular increase of stature in developed countries. These etiologic factors are not found in our West African population.

Prevalence and risk factors of diabetes mellitus in the rural region of Mali (West Africa): a practical approach

A wide-range analytical study for screening diabetes mellitus in the rural region of the Republic of Mali was carried out on 7,472 subjects in whom fasting glycaemia was determined using reflectometry kits. Our results represent a breakthrough in the field of epidemiology of diabetes mellitus in West Africa. The prevalence rate of fasting hyperglycaemia equal to or over 7.00 mmol/l was 0.92%. The statistical analysis of data collected in this manner showed an increased prevalence in the Caucasian and Fulani ethnic groups, and a decreased prevalence in the Negroid ethnic groups. Age and body mass index are also risk factors in this population.