Malawian Infants Research Articles

A pharmacokinetic randomised interventional study to optimise dihydroartemisinin-piperaquine dosing for malaria preventive treatment in Malawian infants: A protocol for the OPTIMAL study

Background A newer malaria preventive treatment, dihydroartemisinin-piperaquine (DP), has been identified as an effective alternative to sulfadoxine-pyrimethamine, to which malaria parasites are increasingly becoming resistant. However, how best to dose DP to safely prevent malaria in infants when aligned with routine health facility visits remains unresolved. As infants are usually excluded from participating in early dose optimisation clinical trials, the present study seeks to shift the paradigm and develop optimised DP dosing strategies for malaria preventive treatment in infants. Methods A randomised, single-blind, placebo-controlled, two-arm, interventional study will be conducted in southern Malawi. At 10 weeks (2.5 months) of age, 220 eligible infants will be randomised to receive DP (intervention group, n=110) or placebo (control group, n=110) with routine vaccines. They will be followed until 12 months of age and receive three further DP or placebo treatment courses at 14 weeks, six- and nine months. Infants in the intervention group will contribute capillary samples for piperaquine concentrations pre-dose and at three-, seven-, 14- and 28-days post-DP dosing as well as capillary samples pre-dose and on day 28 post-DP to quantify malaria parasitaemia using microscopy and quantitative PCR. In the control group, infants will contribute capillary blood samples for malaria parasitaemia at the same time points as the intervention group. Malaria incidence and adverse events will be compared between the two groups. Population pharmacokinetic-pharmacodynamic modelling techniques will be applied to derive feasible, optimised, efficacious, and safe DP dosing strategies for malaria preventive treatment in infancy. Conclusions The findings will provide the much-needed evidence to inform DP dosing for malaria preventive treatment in infants when administered with routine health facility visits. Additionally, they will help inform optimal DP dosing for malaria treatment in infants. The trial was registered with the Pan African Clinical Trials Registry; (PACTR202211575727659) on 8 November 2022. Protocol version 3.1, dated 29 September 2022.

Associations of fish and meat intake with iron and anaemia in Malawian children.

Animal flesh foods are rich in bioavailable iron but infrequently consumed by young children. We aimed to determine whether flesh food intake was associated with iron and anaemia status among 585 Malawian infants enroled in a 6-month egg-feeding trial. The percentage of days of small fish, large fish and meat consumption were assessed through weekly 7-day animal-source food screeners. Grams of intake were assessed through 24-h recalls conducted at 6-9, 9-12 and 12-15 months of age. Plasma ferritin, soluble transferrin receptor (sTfR) and haemoglobin concentrations were measured at 6-9 and 12-15 months of age. Iron biomarkers were adjusted for inflammation during analysis. At enrolment, each flesh food category was consumed by <5% of children in the past 24 h. Over the next 6 months, small fish, large fish and meat were consumed on 25%, 8% and 6% of days, respectively, with mean usual intakes of <5 g/day. More frequent small fish consumption was associated with lower sTfR (geometric mean ratio [95% CI]: 0.98 mg/L [0.96, 1.00] per 10 percentage point difference) but not ferritin (1.03 µg/L [0.98, 1.07]) or haemoglobin (1.01 g/dL [1.00, 1.01]). Large fish consumption was associated with higher anaemia (prevalence ratio [95% CI]: 1.09 [1.01, 1.19]) and lower iron deficiency (0.96 [0.93, 1.00]) prevalence. Gram intakes of flesh food categories were not associated with any iron or anaemia indicators. Small fish were a primary contributor to flesh food intake in this cohort of Malawian children, although usual portions were small. Fish was associated with modest improvements to iron status, but meat was too infrequent to be associated with anaemia and iron deficiency.

Insufficient measles antibody protection in 6-month-old Malawian infants: Reconsider vaccination schedule?

Measles vaccination is currently recommended at 9 months, since maternal antibodies are supposed to protect infants until that age. In this study of 6-month-old Malawian infants 98.3% (58/59) had non-protective IgG levels against measles, irrespective of HIV exposure. Anticipating the first dose at 6 months could be considered.

Cytomegalovirus viremia in HIV-exposed and HIV-unexposed infants in Malawi

In sub-Saharan Africa the great majority of infants acquire Cytomegalovirus (CMV) infection within the first year of life. Maternal long-term antiretroviral therapy (ART) has been suggested to reduce the rate of CMV acquisition in HIV-exposed infants. In the present study serum samples collected at 6 months of age from HIV-exposed and HIV-unexposed infants were analyzed for the presence of CMV DNA (with CMV positivity defined by levels of CMV DNA > 1000 UI/ml). Twenty out of 58 (34.5%) infants had CMV DNA > 1000 UI/ml. There was no difference in the prevalence of CMV viremia between HIV-exposed and -unexposed infants [33.3% (15/45) vs 38.5% (5/13), respectively, P = 0.488]. In the HIV-exposed group, mothers of CMV-negative infants had received a longer antiretroviral treatment before delivery in comparison to mothers of CMV-positive infants (28 vs 3 months, P = 0.187). No differences in weights and lengths at birth, and at 1, 6 and 12 months were observed between CMV-positive and CMV-negative infants. In this study, the prevalence of CMV viremia at six months of age was high in infants born to HIV-positive mothers receiving long-term ART, similar to that of HIV-unexposed infants. Considering the possible relevant impact of CMV on infant health, strategies for containment of the infection should be explored.

Rates of Seroprotection against Vaccine-Preventable Infectious Diseases in HIV-Exposed and -Unexposed Malawian Infants.

The evaluation of seroprotection rates against vaccine-preventable infectious diseases allows for the identification of risk populations. HIV-exposed infants, even if not infected with HIV, have higher morbidity and mortality in comparison to unexposed counterparts. The aim of this study was to compare the specific IgG levels against Haemophilus influenzae type-B (HiB), Hepatitis-B (HBV), and Streptococcus pneumoniae (Spn) in two groups of infants (HIV-exposed and HIV-unexposed) living in Malawi. Blood samples from 62 infants, 49 HIV-exposed, uninfected (HEU), and born to women living with HIV and 13 HIV-unexposed and uninfected (HUU), were collected at 6 months, and specific IgG levels were determined using ELISA tests. The antibody levels against HiB, HBV, and Spn were similar in the two groups. At six months, all HUU infants and 81.6% of HEU infants showed seroprotective levels against HiB, while a percentage of protection varying from 80.6 to 84.6% was observed for HBV and Spn regardless of HIV exposure. Only 59.2% of HEU and 69.2% of HUU infants showed antibody protection against all three pathogens. These results indicate similar rates of seroprotection among HEU and HUU infants but also suggest that a consistent fraction of infants received incomplete vaccinations. Strategies to enforce participation in immunization programs in Malawi should be a health priority.

The H-HOPE behavioral intervention plus Kangaroo Mother Care increases mother-preterm infant responsivity in Malawi: a prospective cohort comparison

BackgroundEarly behavioral intervention to promote development is recommended as the standard of care for preterm infants, yet is not provided in Malawi. One such intervention is H-HOPE (Hospital to Home: Optimizing the Premature Infant’s Environment). In US studies, H-HOPE increased mother-preterm infant responsivity at 6-weeks corrected age (CA). Kangaroo Mother Care (KMC) improves infant survival and is the standard of care for preterm infants in Malawi. This is the first study to examine whether H-HOPE is feasible and promotes mother-preterm infant responsivity in Malawi, and the first to examine the impact of H-HOPE when KMC is the standard of care.MethodThis pilot was conducted in a KMC unit using a prospective cohort comparison design. Because the unit is an open room without privacy, random assignment would have led to contamination of the control cohort. H-HOPE includes participatory guidance for mothers and Massage + , a 15 min multisensory session provided by mothers twice daily. H-HOPE began when infants were clinically stable and at least 32 weeks postmenstrual age. Mothers participated if they were physically stable and willing to return for follow-up. Mother-preterm infant dyads were video-recorded during a play session at 6-weeks CA. Responsivity was measured using the Dyadic Mutuality Code (DMC).ResultsThe final sample included 60 H-HOPE + KMC and 59 KMC only mother-preterm infant dyads. Controlling for significant maternal and infant characteristics, the H-HOPE + KMC dyads were over 11 times more likely to have higher responsivity than those in the KMC only dyads (AOR = 11.51, CI = 4.56, 29.04). The only other factor related to higher responsivity was vaginal vs. Caesarian delivery (AOR = 5.44, CI = .096, 30.96).ConclusionThis study demonstrated that H-HOPE can be provided in Malawi. Mother-infant dyads receiving both H-HOPE and KMC had higher responsivity at 6-weeks CA than those receiving KMC only. H-HOPE was taught by nurses in this study, however the nursing shortage in Malawi makes H-HOPE delivery by nurses challenging. Training patient attendants in the KMC unit is a cost-effective alternative. H-HOPE as the standard of care offers benefits to preterm infants and mothers that KMC alone does not provide.

Triple Benefit: Impact of an Integrated Early Childhood Development and PMTCT Intervention on ART Outcomes Among Mothers Living with HIV and Infants in Malawi—An Endline Evaluation

We conducted a programmatic, observational cohort study with mother-infant pairs (MIPs) enrolled in prevention-of-mother-to-child-transmission (PMTCT) programs in Malawi to assess the feasibility and potential HIV-related benefits of integrating Early Childhood Development (ECD) services into PMTCT programs. Six health facilities were included in the intervention. We offered ECD counseling from the WHO/UNICEF Care for Child Development package in PMTCT waiting spaces while MIPs waited for PMTCT and broader treatment consultations. Primary outcomes were mothers’ retention in HIV care at 12 months and infant HIV testing at 6 weeks and 12 months after birth. Routine facility-level data from six comparison health facilities were collected as an adhoc standard of care comparison and used to calculate the cost of delivering the intervention. A total of 607 MIPs were enrolled in the integrated ECD-PMTCT intervention between June 2018 and December 2019. The average age of MIPs was 30 years and 7 weeks respectively. We found that 86% of mothers attended ≥ 5 of the 8 ECD sessions over the course of 12 months; 88% of intervention mothers were retained in PMTCT versus 59% of mothers in comparison health facilities, and 96% of intervention infants were tested for HIV by six weeks compared to 66% of infants in comparison health facilities. Costing data demonstrated the financial feasibility of integrating ECD and PMTCT programs in government health facilities in Malawi. Integrating ECD into PMTCT programs was feasible, acceptable, resulted in better programmatic outcomes for both mothers and infants. Further investigation is required to determine optimal delivery design for scale-up.

A 12-month Prospective Study of HIV-infected and HIV-uninfected Women and Their Infants in Malawi: Comparative Analysis of Clinical Events and Infant Growth.

Few studies have compared clinical outcomes in HIV-exposed uninfected (HEU) and HIV-unexposed uninfected (HUU) infants in the current scenario of universal and lifelong maternal antiretroviral therapy (ART). HIV-uninfected and HIV-infected Malawian women receiving ART and their breastfed infants were followed for 12 months postpartum, analyzing the rates of infectious and noninfectious events and assessing infant growth at 6 weeks, 6 months, and 12 months. The cohorts included 227 mothers (70 HIV-negative, 157 HIV-positive) and 235 infants (72 HUU, 163 HEU). No maternal or infant deaths occurred during follow-up. HIV-negative women were less likely to complete follow-up (48.6% versus 91.1%). Mothers with and without HIV had similar rates of both infectious and noninfectious events per person-month. Infants who were HEU, compared with HUU, had higher rates of events of any type, lower respiratory tract infections (LRTI), and noninfectious events. HEU had lower body mass index (BMI) at 6 weeks but did not differ from HUU in all anthropometric measures at 6 and 12 months; in growth between 6 weeks and 12 months; and in occurrence of stunting, underweight, and wasting at 6 weeks, 6 months, and 12 months. During the first year of life, infants who were HEU, compared with HUU, showed a transiently lower BMI and an increased risk of LRTI.

The Association among Malaria in Pregnancy, Neonatal inflammation, and Neurocognitive Development in a Cohort of Malawian Infants.

Malaria in pregnancy (MIP) causes poor birth outcomes, but its impact on neurocognitive development has not been well characterized. Between 2012 and 2014, we enrolled 307 mother-infant pairs and monitored 286 infants for neurocognitive development using the Malawi Developmental Assessment Tool at 6, 12, and 24 months of age. MIP was diagnosed from peripheral blood and placental specimens. Cord blood cytokine levels were assessed for a subset of neonates. Predictors of neurodevelopment were examined using mixed-effect logistic regression for developmental delay. Among the participants, 78 mothers (25.4%) had MIP, and 45 infants (15.7%) experienced severe neurocognitive delay. MIP was not associated with differences in cord blood cytokine levels or neurocognitive development. Preterm birth, low birthweight, increasing maternal education level, and increasing interleukin 6 levels were associated significantly with delay. The results highlight the prevalence of severe delay and a need for broad access to early childhood support in this setting.

Quality of antibody responses by adults and young children to 13-valent pneumococcal conjugate vaccination and Streptococcus pneumoniae colonisation

Childhood pneumococcal conjugate vaccine (PCV) protects against invasive pneumococcal disease caused by vaccine-serotype (VT) Streptococcus pneumoniae by generating opsonophagocytic anti-capsular antibodies, but how vaccination protects against and reduces VT carriage is less well understood. Using serological samples from PCV-vaccinated Malawian individuals and a UK human challenge model, we explored whether antibody quality (IgG subclass, opsonophagocytic killing, and avidity) is associated with protection from carriage. Following experimental challenge of adults with S. pneumoniae serotype 6B, 3/21 PCV13-vaccinees were colonised with pneumococcus compared to 12/24 hepatitis A-vaccinated controls; PCV13-vaccination induced serotype-specific IgG, IgG1, and IgG2, and strong opsonophagocytic responses. However, there was no clear relationship between antibody quality and protection from carriage or carriage intensity after vaccination. Similarly, among PCV13-vaccinated Malawian infants there was no relationship between serotype-specific antibody titre or quality and carriage through exposure to circulating serotypes. Although opsonophagocytic responses were low in infants, antibody titre and avidity to circulating serotypes 19F and 6A were maintained or increased with age. These data suggest a complex relationship between antibody-mediated immunity and pneumococcal carriage, and that PCV13-driven antibody quality may mature with age and exposure.

Dynamics of SARS-CoV-2 exposure in Malawian infants between February 2020 and May 2021

BackgroundVery limited information is available on SARS-CoV-2 seroprevalence in infants in sub-Saharan countries. ObjectiveIn this study, we aimed to determine the rate and the temporal evolution of SARS CoV-2 seropositivity in breastfed Malawian infants. Study designBlood samples (n = 250) from 158 infants, born to HIV-negative women and women living with HIV, collected from February 2020 to May 2021, were first tested using an Anti-IgG/A/M SARS CoV 2 ELISA assay against trimeric spike protein, and then, if positive, confirmed using a second ELISA assay detecting IgG against Receptor Binding Domain. ResultsThe confirmed prevalence of anti-SARS CoV-2 antibodies was 31.0% (95% CI: 23.7%-38.3%) with no significant difference between HIV-exposed and HIV-unexposed infants (29.3% and 37.1% respectively, P = 0.410). The presence of anti-SARS-CoV-2 IgG was not associated with maternal socioeconomic or demographic indices. ConclusionsOur data underline the wide spread of the SARS-CoV-2 infection in the pediatric population in sub-Saharan Africa. Design of more specific serological tests for African samples and improvements in serosurveillance programs are needed for more rigorous monitoring of the dynamics of SARS-CoV-2 infection in Africa.

Frequency of Small Fish Consumption Is Associated With Improved Iron and Hemoglobin in Young Malawian Children

ObjectivesOur objective was to assess whether fish and meat consumption over 6mo was associated with plasma ferritin, soluble transferrin receptor (sTfR), hemoglobin (Hb), iron deficiency (ID), and anemia in a population of young Malawian children with a high (>50%) prevalence of iron deficiency anemia.MethodsThis secondary data analysis includes 585 Malawian infants, age 6–9mo, from a 6mo egg feeding trial. At enrollment and 6mo follow-up, 24hr dietary recalls and blood draws were conducted. Days with any small fish, large fish, or meat consumption were reported weekly in 7-day food frequency questionnaires. The % of days with flesh food consumption were totaled for each child. Plasma ferritin, sTfR, and Hb were assessed for associations with the % of days with small fish, large fish, and meat intake using linear regression. Prevalence ratios (PR) of ID (ferritin < 12µg/L or sTfR > 8.3 mg/L) and anemia (Hb< 11g/dL) were compared for each flesh food category using log binomial or modified Poisson regression.ResultsThe % of children with observed intake of small fish (4%), large fish (1%), and meat (2%) from 24-hr recalls at enrollment increased to 40%, 12%, and 9%, respectively, at the 6mo follow-up. Over 6mo, children averaged consumption of small fish, large fish, and meat on 25%, 8%, and 6% of days, respectively. More frequent intake of small fish was associated with higher Hb [geometric mean ratio (95% CI) per 10 percentage point difference: 1.01 g/dL (1.00, 1.01)] and lower sTfR [0.98 mg/L (0.96, 1.00)] but was not associated with ferritin concentration [1.03 µg/L (0.99, 1.07)]; nor was it associated with the prevalence of ID [PR (95% CI): 0.99 (0.97, 1.01)] or anemia [0.94 (0.88, 1.01)]. More frequent consumption of large fish was associated with a higher prevalence of anemia [1.09 per 10 percentage point difference in frequency, (1.00, 1.18)] but was not associated with ID [0.96 (0.92, 1.00)]. Meat consumption was predominantly chicken and not associated with iron or anemia indices.ConclusionsSmall fish are a primary contributor to total flesh food intake of young Malawian children and may provide modest improvements to iron status and hemoglobin. Meat and large fish were infrequently consumed and not associated with ID.Funding SourcesBill & Melinda Gates Foundation.

M084 Rotavirus vaccine shedding is associated with increased frequency of circulating class-switched memory B-cells in Malawian infants

M084 Rotavirus vaccine shedding is associated with increased frequency of circulating class-switched memory B-cells in Malawian infants

Immunoglobulin G passive transfer from mothers to infants: total IgG, IgG subclasses and specific antipneumococcal IgG in 6-week Malawian infants exposed or unexposed to HIV

BackgroundThe impaired transplacental passage of IgG from mothers living with HIV to their infants could be one of the causes of the high vulnerability to infections of HIV-exposed uninfected (HEU) infants, but controversial results have been obtained in different settings. The aim of this study was to assess in 6-week old HEU and HIV-unexposed, uninfected (HUU) Malawian infants the total IgG levels, the subclasses profile and the concentrations of global anti-pneumococcal capsular polysaccharide (anti-PCP) IgG and IgG2.MethodsDried blood spots were collected from 80 infants (40 HEU, 40 HUU) and antibodies concentrations determined by nephelometric method (total IgG and subclasses), or using ELISA (anti-PCP total IgG and IgG2). Results are expressed as median levels with IQR, while the proportions of each subclass out of the total IgG are used to describe the subclasses profile.ResultsAt 6 weeks HEU infants had higher median levels of total IgG and IgG1 and a significantly lower level of IgG2 [0.376 (0.344–0.523) g/l vs 0.485 (0.374–0.781) g/l, p = 0.037] compared to the HUU counterparts. The IgG subclasses distribution confirmed the underrepresentation of IgG2 (IgG2 represented 5.82% of total IgG in HEU and 8.87% in HUU). The anti-PCP IgG and IgG2 levels were significantly lower in HEU infants [8.9 (5.4–15.1) mg/l vs 16.2 (9.61–25.8) mg/l in HUU, p < 0.001, and 2.69 (1.90–4.29) mg/l vs 4.47 (2.96–5.71) mg/l in HUU, p = 0.001, respectively].ConclusionCompared to HUU infants, HEU infants have IgG abnormalities mainly represented by low IgG2 levels, suggesting that despite maternal antiretroviral therapy, the mechanisms of IgG transplacental passage continue to be impaired in women living with HIV. HEU infants also showed a significantly lower level of specific anti-PCP IgG, possibly favouring a high vulnerability to S. pneumoniae infection at an age when protection is mostly depending on maternal IgG.

Longitudinal Assessment of Prenatal, Perinatal, and Early-Life Aflatoxin B1 Exposure in 828 Mother–Child Dyads from Bangladesh and Malawi

BackgroundIn utero or early-life exposure to aflatoxin, which contaminates staple crops in disadvantaged settings, may compromise pregnancy and infant outcomes, but investigations into the extent, persistence, and determinants of aflatoxin exposure at these life stages have lacked longitudinal data collection and broad geographic representation. ObjectivesAflatoxin exposure and selected determinants thereof were characterized in mother–child dyads with serial plasma/serum samples in prenatal, perinatal, and early life in Malawi and Bangladesh. MethodsCirculating aflatoxin B1 (AFB1)–lysine albumin adducts were measured in dyads from Bangladesh (n = 573; maternal first and third trimester, 3 mo postpartum, cord blood, infant 24 mo) and Malawi (n = 255; maternal second and third trimester, 6 mo postpartum, infant 6 and 18 mo) with isotope dilution mass spectrometry. We examined AFB1-lysine adduct magnitude, persistence, seasonality, and associations with infant feeding, and estimated daily AFB1 intake. ResultsMaternal AFB1-lysine was higher in Malawi (98% detectable; median: 0.469, IQR: 0.225–1.027 pg/µL) than in Bangladesh (59%; 0.030, nondetectable [nd]–0.077 pg/µL). Although estimated dietary exposure in Malawi was temporally stable (648 ng AFB1/day), estimated intake in Bangladesh was reduced by 94% between rainy and winter seasons (98 to 6 ng/day). AFB1-lysine was low in cord blood from Bangladesh (15% detectable; 0.045, 0.031–0.088 pg/µL among detectable) and in Malawian infants at 6 mo of age (0.072, nd–0.236 pg/µL), but reached maternal concentrations by 18 or 24 mo (Bangladesh: 0.034, nd–0.063 pg/µL; Malawi: 0.370, 0.195–0.964 pg/µL). In Malawian infants, exclusive breastfeeding at 3 mo was associated with 58% lower AFB1-lysine concentrations at 6 mo compared with other feeding modes (P = 0.010). ConclusionsAmong pregnant women, aflatoxin exposure was persistently high in Malawi, while lower and seasonal in Bangladesh. Infants were partially protected from exposure in utero and with exclusive breastfeeding, but exposures reached adult levels by 18–24 mo of age. The Bangladesh and Malawi trials are registered at clinicaltrials.gov as NCT00860470 and NCT01239693.

Association between household air pollution and nasopharyngeal pneumococcal carriage in Malawian infants (MSCAPE): a nested, prospective, observational study

SummaryBackgroundHousehold air pollution from solid fuels increases the risk of childhood pneumonia. Nasopharyngeal carriage of Streptococcus pneumoniae is a necessary step in the development of pneumococcal pneumonia. We aimed to assess the association between exposure to household air pollution and the prevalence and density of S pneumoniae carriage among children.MethodsThe Malawi Streptococcus pneumoniae Carriage and Air Pollution Exposure study was a nested, prospective, observational study of children participating in the cluster randomised controlled Cooking and Pneumonia Study (CAPS) in the Karonga Health and Demographic Surveillance System (HDSS) area in northern Malawi. CAPS compared the effects of a cleaner burning biomass-fuelled cookstove (intervention group) with traditional open-fire cooking (control group) on the incidence of pneumonia in children. Eligible children aged 6 weeks or 6 months (those recruited a 6 weeks were also followed up at age 6 months) were identified by the Karonga HDSS centre. Nasopharyngeal swabs were taken to detect S pneumoniae, and infant exposure to particulate matter with a diameter of ≤2·5 μm (PM2·5) exposure was assessed by use of a MicroPEM device. The primary outcome was the prevalence of nasopharyngeal S pneumoniae carriage in all children aged 6 months, assessed in all children with valid data on PM2·5. The effects of the intervention stoves (intention-to-treat analysis) and PM2·5 (adjusted exposure-response analysis) on the prevalence of S pneumoniae carriage were also assessed in the study children.FindingsBetween Nov 15, 2015, and Nov 2, 2017, 485 children were recruited (240 from the intervention group and 245 from the control group). Of all 450 children with available data at age 6 months, 387 (86% [95% CI 82–89]) were positive for S pneumoniae. Geometric mean PM2·5 exposure was 60·3 μg/m3 (95% CI 55·8–65·3) in S pneumoniae-positive children and 47·0 μg/m3 (38·3–57·7) in S pneumoniae-negative children (p=0·044). In the intention-to-treat analysis, a non-significant increase in the risk of S pneumoniae carriage was observed in intervention group children compared with control group children (odds ratio 1·36 [95% CI 0·95–1·94]; p=0·093). In the exposure-response analysis, a significant association between PM2·5 exposure and S pneumoniae carriage was observed; a one unit increase in decile of PM2·5 was found to significantly increase the risk of S pneumoniae carriage by 10% (1·10 [1·01–1·20]; p=0·035), after adjustment for age, sex, 13-valent pneumococcal conjugate vaccination status, season, current use of antibiotics, and MicroPEM run-time.InterpretationDespite the absence of effect from the intervention cookstove, household air pollution exposure was significantly associated with the prevalence of nasopharyngeal S pneumoniae carriage. These results provide empirical evidence for the potential mechanistic association between exposure to household air pollution and childhood pneumonia.FundingBill & Melinda Gates Foundation.

Factors associated with the risk of HIV infection among HIV-exposed infants in Malawi: 2013–2020

BackgroundDespite the availability of individual-level data of infants accessing HIV DNA-PCR testing service, there has been little in-depth analysis of such data. Therefore, we describe trends in risk of HIV...

Plasma Rotavirus-specific IgA and Risk of Rotavirus Vaccine Failure in Infants in Malawi.

BackgroundRotavirus vaccine efficacy is reduced in low-income populations, but efforts to improve vaccine performance are limited by lack of clear correlates of protection. While plasma rotavirus (RV)-specific IgA appears strongly associated with protection against rotavirus gastroenteritis in high-income countries, weaker association has been observed in low-income countries. We tested the hypothesis that lower RV-specific IgA is associated with rotavirus vaccine failure in Malawian infants.MethodsIn a case-control study we recruited infants presenting with severe rotavirus gastroenteritis following monovalent oral rotavirus vaccination (RV1 vaccine failures). Conditional logistic regression was used to determine the odds of rotavirus seronegativity (RV-specific IgA<20 U/mL) in these cases compared 1:1 with age-matched, vaccinated, asymptomatic community controls. Plasma RV-specific IgA was determined by ELISA for all participants at recruitment, and for cases at 10 days post symptom onset. Rotavirus infection and genotype were determined by antigen testing and RT-PCR respectively.ResultsIn 116 age-matched pairs, infants with RV1 vaccine failure were more likely to be RV-specific IgA seronegative than controls: OR 3.1 (95%CI 1.6-5.9), p=0.001. In 60 infants with convalescent serology, 42/45 (93%, 95%CI 81-98%) infants seronegative at baseline became seropositive. Median rise in RV-specific IgA concentration following acute infection was 112.8 (IQR 19.1-380.6) fold.ConclusionsIn this vaccinated population with high residual burden of rotavirus disease, RV1 vaccine failure was associated with lower RV-specific IgA, providing further evidence of RV-specific IgA as a marker of protection. Robust convalescent RV-specific IgA response in vaccine failures suggests differences in wild-type and vaccine-induced immunity, which informs future vaccine development.

Dried blood spots for the quantitative evaluation of IgG isotypes and correlation with serum samples in HIV-exposed uninfected (HEU) infants

BackgroundThe determination of IgG levels and their subclasses can provide clinically relevant information on the status of the immune system. Here we determined the sensitivity and reproducibility of the quantification of IgG subclasses from Dried Blood Spots (DBS) in Malawian uninfected infants exposed to HIV (HEU). MethodsSixty paired samples of serum and DBS from HEU infants were used. Samples were collected from 1, 6, and 24-month old infants. IgGs concentrations from both serum and DBS were analyzed by BN ProSpec Siemens assay, using a different setting for sample dilutions. The reproducibility of the DBS method was tested on 10 samples run twice, starting from the DBS extraction process. To assess the systematic, proportional, and random differences, we computed the Passing-Bablok regression, and the Bland-Altman analysis to estimate the total mean bias between the two tests. ResultsThe IgG isotypes concentrations from serum and DBS showed significant differences in all the comparisons. Generally, the DBS method underestimated IgG subclasses' values showing a recovery range between 51.2% and 77.6%. Passing Bablok regression on age-based groups showed agreement for IgG, IgG1, and IgG2, but not for IgG3 and IgG4. The mean bias obtained with the Bland Altman test varied largely depending on IgG isotypes (−0.02–2.21 g/l) Coefficient of variation <7.0% was found in the repeated tests for IgG, IgG1, IgG3, and IgG4, while it was 12.4% for IgG2. ConclusionsVarying degrees of differences were seen in the IgGs measurement in the two different matrices. In IgGs analysis, the DBS method offers promise for population-based research, but the results should be carefully evaluated and considered as a relative value since they are not equivalent to the serum concentrations.

The effect of bovine colostrum/egg supplementation compared with corn/soy flour in young Malawian children: a randomized, controlled clinical trial

Bovine colostrum with egg powder (BC/egg) is rich in essential amino acids and immunoactive compounds. This trial tested the hypothesis that a daily supplement of BC/egg would reduce linear growth faltering and environmental enteric dysfunction (EED) in Malawian infants when compared with an isoenergetic ration of corn/soy flour used as a control. EED was defined by a lactulose permeability test. This was a prospective, randomized, blinded, placebo-controlled clinical trial in which 9-mo-old infants received BC/egg or a control for 3 mo. The primary outcomes were change in length-for-age z-score (ΔLAZ) and urinary lactulose excretion (%L) at 12-mo-old. Secondary outcomes included episodes of diarrhea, stunting, EED, and the 16S configuration of the fecal microbiota. Of the 277 children enrolled, 267 completed the intervention phase of the study. LAZ decreased in all children from 9 to 17 mo, although ΔLAZ was less in children receiving BC/egg from 9 to 12 mo (difference=0.12 z-scores; P=0.0011). This difference persisted after feeding was completed, with less ΔLAZ (difference=0.09 z-scores). A lower prevalence of stunting was seen in the intervention group (n=47/137) than the control group (n=62/127) at 17 mo (RR = 0.70; 95% CI: 0.52, 0.94).The median %L at 12 mo of age in the children receiving BC/egg was 0.14%, compared with 0.17% in the control group (P=0.74). In children with %L>0.45% at enrollment (severe EED), the BC/egg group had more children with normal %L at 12 mo of age (10/20, 50%) than was seen in controls (2/15, 13%; P=0.024). Episodes of diarrhea and β-diversity of the 16S configuration of fecal microbiota did not differ between the 2 groups. Addition of BC/egg to complementary feeding in Malawian infants resulted in less linear growth faltering. This trial was registered at clinicaltrials.gov as NCT03801317.