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Snakebite clinical trials have often used heterogeneous outcome measures and there is an urgent need for standardisation. A globally representative group of key stakeholders came together to reach consensus on a globally relevant set of core outcome measurements. Outcome domains and outcome measurement instruments were identified through searching the literature and a systematic review of snakebite clinical trials. Outcome domains were shortlisted by use of a questionnaire and consensus was reached among stakeholders and the patient group through facilitated discussions and voting. Five universal core outcome measures should be included in all future snakebite clinical trials—mortality, WHO disability assessment scale, patient-specific functional scale, acute allergic reaction by Brown criteria, and serum sickness by formal criteria. Additional syndrome-specific core outcome measures should be used depending on the biting species. This core outcome measurement set provides global standardisation, supports the priorities of patients and clinicians, enables meta-analysis, and is appropriate for use in low-income and middle-income settings.

Purpose The life-saving role of oxygen therapy in African children with severe pneumonia is not yet established. Methods The open-label fractional-factorial COAST trial randomised eligible Ugandan and Kenyan children aged > 28 days with severe pneumonia and severe hypoxaemia stratum (SpO2 3 h receipt of oxygen were excluded. The primary endpoint was 48 h mortality; secondary endpoints included mortality or neurocognitive sequelae at 28 days. Results The trial was stopped early after enrolling 1852/4200 children, including 388 in the severe hypoxaemia stratum (median 7 months; median SpO2 75%) randomised to HFNT (n = 194) or LFO (n = 194) and 1454 in the hypoxaemia stratum (median 9 months; median SpO2 88%) randomised to HFNT (n = 363) vs LFO (n = 364) vs permissive hypoxaemia (n = 727). Per-protocol 15% of patients in the permissive hypoxaemia group received oxygen (when SpO2

Summary Background Triple antimalarial combination therapies combine potent and rapidly cleared artemisinins or related synthetic ozonides, such as arterolane, with two, more slowly eliminated partner drugs to reduce the risk of resistance. We aimed to assess the safety, tolerability, and efficacy of arterolane–piperaquine–mefloquine versus arterolane–piperaquine and artemether–lumefantrine for the treatment of uncomplicated falciparum malaria in Kenyan children. Methods In this single-centre, open-label, randomised, non-inferiority trial done in Kilifi County Hospital, Kilifi, coastal Kenya, children with uncomplicated Plasmodium falciparum malaria were recruited. Eligible patients were aged 2–12 years and had an asexual parasitaemia of 5000–250 000 parasites per μL. The exclusion criteria included the presence of an acute illness other than malaria, the inability to tolerate oral medications, treatment with an artemisinin derivative in the previous 7 days, a known hypersensitivity or contraindication to any of the study drugs, and a QT interval corrected for heart rate (QTc interval) longer than 450 ms. Patients were randomly assigned (1:1:1), by use of blocks of six, nine, and 12, and opaque, sealed, and sequentially numbered envelopes, to receive either arterolane–piperaquine, arterolane–piperaquine–mefloquine, or artemether–lumefantrine. Laboratory staff, but not the patients, the patients' parents or caregivers, clinical or medical officers, nurses, or trial statistician, were masked to the intervention groups. For 3 days, oral artemether–lumefantrine was administered twice daily (target dose 5–24 mg/kg of bodyweight of artemether and 29–144 mg/kg of bodyweight of lumefantrine), and oral arterolane–piperaquine (arterolane dose 4 mg/kg of bodyweight; piperaquine dose 20 mg/kg of bodyweight) and oral arterolane–piperaquine–mefloquine (mefloquine dose 8 mg/kg of bodyweight) were administered once daily. All patients received 0·25 mg/kg of bodyweight of oral primaquine at hour 24. All patients were admitted to Kilifi County Hospital for at least 3 consecutive days and followed up at day 7 and, thereafter, weekly for up to 42 days. The primary endpoint was 42-day PCR-corrected efficacy, defined as the absence of treatment failure in the first 42 days post-treatment, of arterolane–piperaquine–mefloquine versus artemether–lumefantrine, and, along with safety, was analysed in the intention-to-treat population, which comprised all patients who received at least one dose of a study drug. The 42-day PCR-corrected efficacy of arterolane–piperaquine–mefloquine versus arterolane–piperaquine was an important secondary endpoint and was also analysed in the intention-to-treat population. The non-inferiority margin for the risk difference between treatments was −7%. The study is registered in ClinicalTrials.gov , NCT03452475 , and is completed. Findings Between March 7, 2018, and May 2, 2019, 533 children with P falciparum were screened, of whom 217 were randomly assigned to receive either arterolane–piperaquine (n=73), arterolane–piperaquine–mefloquine (n=72), or artemether–lumefantrine (n=72) and comprised the intention-to-treat population. The 42-day PCR-corrected efficacy after treatment with arterolane–piperaquine–mefloquine (100%, 95% CI 95–100; 72/72) was non-inferior to that after treatment with artemether–lumefantrine (96%, 95% CI 88–99; 69/72; risk difference 4%, 95% CI 0–9; p=0·25). The 42-day PCR-corrected efficacy of arterolane–piperaquine–mefloquine was non-inferior to that of arterolane–piperaquine (100%, 95% CI 95–100; 73/73; risk difference 0%). Vomiting rates in the first hour post-drug administration were significantly higher in patients treated with arterolane–piperaquine (5%, 95% CI 2–9; ten of 203 drug administrations; p=0·0013) or arterolane–piperaquine–mefloquine (5%, 3–9; 11 of 209 drug administrations; p=0·0006) than in patients treated with artemether–lumefantrine (1%, 0–2; three of 415 drug administrations). Upper respiratory tract complaints (n=26 for artemether–lumefantrine; n=19 for arterolane–piperaquine–mefloquine; n=23 for arterolane–piperaquine), headache (n=13; n=4; n=5), and abdominal pain (n=7; n=5; n=5) were the most frequently reported adverse events. There were no deaths. Interpretation This study shows that arterolane–piperaquine–mefloquine is an efficacious and safe treatment for uncomplicated falciparum malaria in children and could potentially be used to prevent or delay the emergence of antimalarial resistance. Funding UK Department for International Development, The Wellcome Trust, The Bill & Melinda Gates Foundation, Sun Pharmaceutical Industries

Controlled human malaria infection (CHMI) studies involve the deliberate infection of healthy volunteers with malaria parasites under controlled conditions to study immune responses and/or test drug or vaccine efficacy. An empirical ethics study was embedded in a CHMI study at a Kenyan research programme to explore stakeholders' perceptions and experiences of deliberate infection and moral implications of these. Data for this qualitative study were collected through focus group discussions, in-depth interviews and non-participant observation. Sixty-nine participants were involved, including CHMI study volunteers, community representatives and research staff. Data were managed using QSR Nvivo 10 and analysed using an inductive-deductive approach, guided by ethics literature. CHMI volunteers had reasonable understanding of the study procedures. Decisions to join were influenced by study incentives, trust in the research institution, their assessment of associated burdens and motivation to support malaria vaccine development. However, deliberate malaria infection was a highly unusual research strategy for volunteers, community representatives and some study staff. Volunteers' experiences of physical, emotional and social burdens or harms were often greater than anticipated initially, and fluctuated over time, related to specific procedures and events. Although unlikely to deter volunteers' participation in similar studies in furture, we argue that the dissonance between level of understanding of the burdens involved and actual experiences are morally relevant in relation to community engagement, informed consent processes, and ongoing support for volunteers and research staff. We further argue that ethics oversight of CHMI studies should take account of these issues in deciding whether consent, engagement and the balance of benefits and harms are reasonable in a given context.

Natural killer cells are potent immune effectors that can be activated via antibody mediated Fc receptor engagement. Using multiparameter flow cytometry, we found that natural killer (NK) cells degranulate and release IFNγ upon stimulation with antibody-opsonized Plasmodium falciparum merozoites. Antibody-dependent NK activity (Ab-NK) was largely strain-transcending and enhanced the inhibition of invasion into erythrocytes. Ab-NK was associated with the successful control of parasitemia following experimental malaria challenge in African adults. In an independent cohort study in children, Ab-NK increased with age, was boosted by concurrent falciparum infections and associated with a lower risk of clinical episodes of malaria. Nine of 14 vaccine candidates tested induced Ab-NK including some less well-studied antigens - P41, P113, MSP11, RHOPH3, and Pf_11363200. These data highlight an important role for ab-NK in immunity against malaria and provide a new mechanism for the evaluation of vaccine candidatesOne Sentence SummaryAntibody-dependent natural killer activation is induced by merozoites and associated with immunity against malaria

Background: It is unclear if adjunctive steroid therapy reduces mortality in community-acquired pneumonia, as very few studies have had mortality as a primary outcome. This question has become even more relevant following demonstration of a mortality benefit of dexamethasone when used in patients with COVID-19 who had severe disease. This has led to increased prescription of steroids in adults with community acquired pneumonia in low-resource settings even when their COVID-19 diagnosis is uncertain due to low testing rates. This pragmatic parallel randomised-controlled open-label trial will determine if adjunctive low-dose steroids for treatment of adults admitted to hospital with community acquired pneumonia whose SARS-CoV-2 status is either unknown or negative reduces mortality. Methods: We will enroll and randomize 2180 patients admitted with a clinical diagnosis of community acquired pneumonia into two arms; in Stratum A-participants will receive standard care for the treatment of community acquired pneumonia. In Stratum B-participants will receive a 10-day course of low-dose oral corticosteroids in addition to standard care. All participants will be followed up to 30 days post randomization and their final status recorded (alive or dead). An immunology sub study will be conducted on a subset of the trial participants (50 per arm) to determine the correlation of pre-existing and treatment induced immune and metabolic changes with study outcomes. Discussion: Mortality among adults admitted to hospital with community acquired pneumonia in resource-limited settings is high. Steroids are readily available in these settings. If the addition of steroids to standard care for community acquired pneumonia is found to be beneficial, this easily scalable intervention would significantly reduce the currently high mortality associated with the illness.

Background Naturally acquired immunity to malaria is incompletely understood. We used controlled human malaria infection (CHMI) to study the impact of past exposure to malaria in Kenyan adults in relation to infection with a non-Kenyan parasite strain. Methods We administered 3.2x103 aseptic, purified, cryopreserved Plasmodium falciparum (Pf) sporozoites (SPZ) [Sanaria® PfSPZ Challenge, NF54 West African strain] by direct venous inoculation and undertook clinical monitoring and serial quantitative PCR (qPCR) of the 18S ribosomal RNA gene. The study endpoint was met when either: parasitaemia reached ≥500 parasites/μl blood; clinically significant symptoms were seen; or at 21 days after inoculation. All volunteers received antimalarial drug treatment on meeting the endpoint. Results One hundred and sixty-one (161) volunteers underwent CHMI between Aug 4, 2016, and Feb 14, 2018. CHMI was well tolerated with no severe or serious adverse events. Nineteen volunteers (11.8%) were excluded from the analysis based on detection of antimalarial drugs above the minimal inhibitory concentration or parasites genotyped as non-NF54. Of the 142 volunteers who were eligible for analysis: 26 (18.3%) had febrile symptoms and were treated; 30 (21.1%) reached ≥500 parasites/μl and were treated; 53 (37.3%) had parasitaemia without meeting thresholds for treatment and; 33 (23.2%) remained qPCR negative. Conclusion We find that past exposure to malaria, as evidenced by location of residence, in some Kenyan adults can completely suppress in vivo growth of a parasite strain originating from outside Kenya.TRAIL REGISTRATION. The study was registered on ClinicalTrials.gov (NCT02739763). Funding Wellcome Trust.

Background Snakebite is a priority neglected tropical disease and causes a range of complications that vary depending on the snake species. Randomised clinical trials have used varied outcome measures that do not allow results to be compared or combined. In accordance with the Core Outcomes Measurements in Effectiveness Trials (COMET) initiative, this systematic review aims to support the development of a globally relevant core outcome set for snakebite. Methods All randomised controlled trials, secondary analyses of randomised controlled trials and study protocols investigating the efficacy of therapeutics for human snakebite envenoming were eligible for inclusion. Study screening and data extraction were conducted in duplicate by two independent reviewers. All primary and secondary outcome measures were extracted and compiled, as were adverse event outcome measures. Similar outcome measures were grouped into domains. The study was prospectively registered with PROSPERO: CRD42020196160. Results This systematic review included 43 randomised controlled trials, two secondary analyses and 13 study protocols. A total of 382 outcome measures were extracted and, after duplicates were merged, there were 153 unique outcomes. The most frequently used outcome domain (‘venom antigenaemia’) was included in less than one third of the studies. The unique outcomes were classified into 60 outcome domains. Patient-centred outcomes were used in only three of the studies. Discussion Significant heterogeneity in outcome measures exists in snakebite clinical trials. Consensus is needed to select outcome measures that are valid, reliable, patient-centred and feasible. The results of this systematic review strongly support the development of a core outcome set for use in snakebite clinical trials., Author summary Standardised outcome measures for snakebite randomised controlled trials are needed to enable results to be compared and combined between studies. This systematic review was conducted to understand the variations in outcome measure use in snakebite randomised controlled trials, and to create a comprehensive list of outcome measures from which to develop a core outcome set (COS). A total of 153 unique outcome measures were extracted from the 58 studies identified in this systematic review. Of these 153 unique outcome measures, 91 were used in only in a single study. Although a form of bedside whole blood clotting test was used in 30 of the 58 studies, 18 unique methods of measurement were identified. Only three studies, all conducted in the USA, included patient-centred outcomes. This systematic review demonstrates the strong need for a snakebite core outcome set, which will support the adoption of valid, reproducible, and patient-centred outcome measures, and enable downstream meta-analyses.

Background: Children hospitalised with severe acute malnutrition (SAM) are frequently complicated (>50%) by diarrhoea (≥3 watery stools/day) which is accompanied by poor outcomes. Rehydration guidelines for SAM are exceptionally conservative and controversial, based upon expert opinion. The guidelines only permit use of intravenous fluids for cases with advanced shock and exclusive use of low sodium intravenous and oral rehydration solutions (ORS) for fear of fluid and/or sodium overload. Children managed in accordance to these guidelines have a very high mortality. The proposed GASTROSAM trial is the first step in reappraising current recommendations. We hypothesize that liberal rehydration strategies for both intravenous and oral rehydration in SAM children with diarrhoea may reduce adverse outcomes. Methods An open Phase II trial, with a partial factorial design, enrolling Ugandan and Kenyan children aged 6 months to 12 years with SAM hospitalised with gastroenteritis (>3 loose stools/day) and signs of moderate and severe dehydration. In Stratum A (severe dehydration) children will be randomised (1:1:2) to WHO plan C (100mls/kg Ringers Lactate (RL) with intravenous rehydration given over 3-6 hours according to age including boluses for shock), slow rehydration (100 mls/kg RL over 8 hours (no boluses)) or WHO SAM rehydration regime (ORS only (boluses for shock (standard of care)). Stratum B incorporates all children with moderate dehydration and severe dehydration post-intravenous rehydration and compares (1:1 ratio) standard WHO ORS given for non-SAM (experimental) versus WHO SAM-recommended low-sodium ReSoMal. The primary outcome for intravenous rehydration is urine output (mls/kg/hour at 8 hours post-randomisation), and for oral rehydration a change in sodium levels at 24 hours post-randomisation. This trial will also generate feasibility, safety and preliminary data on survival to 28 days. Discussion. If current rehydration strategies for non-malnourished children are safe in SAM this could prompt future evaluation in Phase III trials.

The government of Kenya has launched a phased rollout of COVID-19 vaccination. A major barrier is vaccine hesitancy; the refusal or delay of accepting vaccination. This study evaluated the level and determinants of vaccine hesitancy in Kenya. We conducted a cross-sectional study administered through a phone-based survey in February 2021 in four counties of Kenya. Multivariate logistic regression was used to identify individual perceived risks and influences, context-specific factors, and vaccine-specific issues associated with COVID-19 vaccine hesitancy. COVID-19 vaccine hesitancy in Kenya was high: 60.1%. Factors associated with vaccine hesitancy included: older age, lower education level, perceived difficulty in adhering to government regulations on COVID-19 prevention, less adherence to wearing of face masks, not having ever been tested for COVID-19, no reported socio-economic loss as a result of COVID public-health restriction measures, and concerns regarding vaccine safety and effectiveness. There is a need for the prioritization of interventions to address vaccine hesitancy and improve vaccine confidence as part of the vaccine roll-out plan. These messaging and/or interventions should be holistic to include the value of other public health measures, be focused and targeted to specific groups, raise awareness on the risks of COVID-19 and effectively communicate the benefits and risks of vaccines.

BackgroundNeurological complications due to chikungunya virus (CHIKV) infection have been described in different parts of the world, with children being disproportionately affected. However, the burden of CHIKV-associated neurological disease in Africa is currently unknown.MethodsWe estimated the incidence of CHIKV infection among children hospitalised with neurological disease in coastal Kenya. We used reverse-transcriptase polymerase chain reaction (RT-PCR) to systematically test for CHIKV in cerebrospinal fluid (CSF) samples from children aged FindingsThere were 18,341 paediatric admissions during the 5-year study period, of which 4,332 (24%) had CSF collected. The most common clinical reasons for CSF collection were impaired consciousness, seizures and coma (47%, 22% and 21% of all collections, respectively). After acute investigations done for immediate clinical care, CSF samples were available for 3,980 admissions, of which 367 (9.2%) were CHIKV RT-PCR positive. The annual incidence of CHIKV-associated neurological disease varied between 13 to 58 episodes per 100,000 person-years among all children InterpretationAlthough not previously recognized, CHIKV-associated neurological disease is common in coastal Kenya and a significant public health burden.

BACKGROUND: Non-typhoidal salmonella can cause serious, life-threatening invasive infections involving the bloodstream and other normally sterile sites. We aimed to systematically review the prevalence of complications and case-fatality ratio (CFR) of non-typhoidal salmonella invasive disease to provide contemporary global estimates and inform the development of vaccine and non-vaccine interventions. METHODS: We did a global systematic review and meta-analysis of studies investigating the complications and mortality associated with non-typhoidal salmonella invasive disease. We searched Embase, MEDLINE, Web of Science, and PubMed for peer-reviewed, primary research articles published from database inception up to June 4, 2021, with no restrictions on language, country, date, or participant demographics. Only studies reporting the proportion of complications or deaths associated with non-typhoidal salmonella invasive disease, confirmed by culture of samples taken from a normally sterile site (eg, blood or bone marrow) were included. We excluded case reports, case series, policy reports, commentaries, editorials, and conference abstracts. Data on the prevalence of complications and CFR were abstracted. The primary outcomes were to estimate the prevalence of complications and CFR of non-typhoidal salmonella invasive disease. We calculated an overall pooled CFR estimate and pooled CFR stratified by UN region, subregion, age group, and by serovar when available with a random-effects meta-analysis. A risk-of-bias assessment was done, and heterogeneity was assessed with Cochran's Q Test, I2, and τ2. This study was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and is registered with PROSPERO, CRD42020202293. FINDINGS: The systematic review returned a total of 8770 records. After duplicates were removed, 5837 titles and abstracts were screened, yielding 84 studies from 35 countries after exclusions. Of these included studies, 77 (91·7%) were hospital-based and 66 (78·6%) were located in Africa or Asia. Among 55 studies reporting non-typhoidal salmonella disease-associated complications, a total of 45 different complications were reported and 1824 complication events were identified among 6974 study participants. The most prevalent complication was septicaemia, occurring in 171 (57·2%) of 299 participants, followed by anaemia in 580 (47·3%) of 1225 participants. From 81 studies reporting the CFR of non-typhoidal salmonella invasive disease, the overall pooled CFR estimate was 14·7% (95% CI 12·2-17·3). When stratified by UN region, the pooled CFR was 17·1% (13·6-21·0) in Africa, 14·0% (9·4-19·4) in Asia, 9·9% (6·4-14·0) in Europe, and 9·6% (0·0-25·1) in the Americas. Of all 84 studies, 66 (78·6%) had an overall high risk of bias, 18 (21·4%) had a moderate risk, and none had a low risk. Substantial heterogeneity (I2>80%) was observed in most (15 [65·2%] of 23) CFR estimates. INTERPRETATION: Complications were frequent among individuals with non-typhoidal salmonella invasive disease and approximately 15% of patients died. Clinicians, especially in African countries, should be aware of non-typhoidal salmonella invasive disease as a cause of severe febrile illness. Prompt diagnoses and management decisions, including empiric antimicrobial therapy, would improve patient outcomes. Additionally, investments in improving clinical microbiology facilities to identify non-typhoidal salmonella and research efforts towards vaccine development and non-vaccine prevention measures would prevent non-typhoidal salmonella invasive disease-associated illness and death. FUNDING: EU Horizon 2020 research and innovation programme. ispartof: LANCET INFECTIOUS DISEASES vol:22 issue:5 pages:692-705 ispartof: location:United States status: published

Background Human infection studies (HIS) that involve deliberately infecting healthy volunteers with a pathogen raise important ethical issues, including the need to ensure that benefits and burdens are understood and appropriately accounted for. Building on earlier work, we embedded social science research within an ongoing malaria human infection study in coastal Kenya to understand the study benefits and burdens experienced by study stakeholders in this low-resource setting and assess the wider implications for future research planning and policy. Methods Data were collected using qualitative research methods, including in-depth interviews (44), focus group discussions (10) and non-participation observation. Study participants were purposively selected (key informant or maximal diversity sampling), including volunteers in the human infection study, study staff, community representatives and local administrative authorities. Data were collected during and up to 18 months following study residency, from sites in Coastal and Western Kenya. Voice recordings of interviews and discussions were transcribed, translated, and analysed using framework analysis, combining data- and theory-driven perspectives. Findings Physical, psychological, economic and social forms of benefits and burdens were experienced across study stages. Important benefits for volunteers included the study compensation, access to health checks, good residential living conditions, new learning opportunities, developing friendships and satisfaction at contributing towards a new malaria vaccine. Burdens primarily affected study volunteers, including experiences of discomfort and ill health; fear and anxiety around aspects of the trial process, particularly deliberate infection and the implications of prolonged residency; anxieties about early residency exit; and interpersonal conflict. These issues had important implications for volunteers’ families, study staff and the research institution’s reputation more widely. Conclusion Developing ethically and scientifically strong HIS relies on grounded accounts of volunteers, study staff and the wider community, understood in the socioeconomic, political and cultural context where studies are implemented. Recognition of the diverse, and sometimes perverse, nature of potential benefits and burdens in a given context, and who this might implicate, is critical to this process. Prior and ongoing stakeholder engagement is core to developing these insights.

BACKGROUND: A safe and efficacious vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), if deployed with high coverage, could contribute to the control of the COVID-19 pandemic. We evaluated the safety and efficacy of the ChAdOx1 nCoV-19 vaccine in a pooled interim analysis of four trials. \ud \ud \ud METHODS: This analysis includes data from four ongoing blinded, randomised, controlled trials done across the UK, Brazil, and South Africa. Participants aged 18 years and older were randomly assigned (1:1) to ChAdOx1 nCoV-19 vaccine or control (meningococcal group A, C, W, and Y conjugate vaccine or saline). Participants in the ChAdOx1 nCoV-19 group received two doses containing 5 × 1010 viral particles (standard dose; SD/SD cohort); a subset in the UK trial received a half dose as their first dose (low dose) and a standard dose as their second dose (LD/SD cohort). The primary efficacy analysis included symptomatic COVID-19 in seronegative participants with a nucleic acid amplification test-positive swab more than 14 days after a second dose of vaccine. Participants were analysed according to treatment received, with data cutoff on Nov 4, 2020. Vaccine efficacy was calculated as 1 - relative risk derived from a robust Poisson regression model adjusted for age. Studies are registered at ISRCTN89951424 and ClinicalTrials.gov, NCT04324606, NCT04400838, and NCT04444674. \ud \ud \ud FINDINGS: Between April 23 and Nov 4, 2020, 23 848 participants were enrolled and 11 636 participants (7548 in the UK, 4088 in Brazil) were included in the interim primary efficacy analysis. In participants who received two standard doses, vaccine efficacy was 62·1% (95% CI 41·0-75·7; 27 [0·6%] of 4440 in the ChAdOx1 nCoV-19 group vs71 [1·6%] of 4455 in the control group) and in participants who received a low dose followed by a standard dose, efficacy was 90·0% (67·4-97·0; three [0·2%] of 1367 vs 30 [2·2%] of 1374; pinteraction=0·010). Overall vaccine efficacy across both groups was 70·4% (95·8% CI 54·8-80·6; 30 [0·5%] of 5807 vs 101 [1·7%] of 5829). From 21 days after the first dose, there were ten cases hospitalised for COVID-19, all in the control arm; two were classified as severe COVID-19, including one death. There were 74 341 person-months of safety follow-up (median 3·4 months, IQR 1·3-4·8): 175 severe adverse events occurred in 168 participants, 84 events in the ChAdOx1 nCoV-19 group and 91 in the control group. Three events were classified as possibly related to a vaccine: one in the ChAdOx1 nCoV-19 group, one in the control group, and one in a participant who remains masked to group allocation. \ud \ud \ud INTERPRETATION: ChAdOx1 nCoV-19 has an acceptable safety profile and has been found to be efficacious against symptomatic COVID-19 in this interim analysis of ongoing clinical trials. \ud \ud \ud FUNDING: UK Research and Innovation, National Institutes for Health Research (NIHR), Coalition for Epidemic Preparedness Innovations, Bill & Melinda Gates Foundation, Lemann Foundation, Rede D'Or, Brava and Telles Foundation, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midland's NIHR Clinical Research Network, and AstraZeneca.

BackgroundYellow fever vaccine stocks have been insufficient to cover exceptional demands for outbreak response. Fractional dosing evidence is limited to the 17DD substrain vaccine. We assessed the immunogenicity and safety of one-fifth fractional dose compared to standard dose of each of the four WHO-prequalified yellow fever vaccines produced from three substrains.MethodsWe conducted a randomized, double-blind, non-inferiority trial in Mbarara, Uganda and Kilifi, Kenya. 960 participants aged 18-59 years without previous yellow fever vaccination or infection were recruited from communities and randomized to receive one of four vaccines and to standard or fractional dosage. Vaccine was administered subcutaneously by unblinded nurse. Other study personnel and participants were blinded to vaccine allocation. Primary immunogenicity outcome, seroconversion, was measured in the per-protocol population; safety outcomes included all vaccinated participants. We defined non-inferiority as no more than 10% decrease in seroconversion in fractional compared to standard dose arms 28 days post-vaccination. Seroconversion was defined as ≥4-fold rise in neutralizing antibody titers measured by 50% plaque reduction neutralization test (PRNT50).ClinicalTrials.gov Identifier: NCT02991495, following participants.FindingsBetween 6th November 2017 and 21st February 2018, 960 participants, total sample goal, were randomized. The primary per-protocol analysis includes 899 participants, with 110 to 117 participants per arm. The absolute difference in seroconversion between fractional and standard doses by vaccine was 1.71% (95%CI: −2.60, 5.28), −0.90% (95%CI: −4.24, 3.13), 1.82% (95%CI: −2.75, 5.39), 0.0% (95%CI: −3.32, 3.29). Fractional doses from all four vaccines met the non-inferiority criterion. There were no safety concerns.InterpretationThese results support fractional dosing of all WHO-prequalified yellow fever vaccines for the general adult population for outbreak response in situations of vaccine shortage.FundingThe study was funded by Médecins Sans Frontières Foundation, Wellcome Trust (grant no. 092654) and the UK Department for International Development. Vaccines were donated in kind.Research in contextEvidence before this studyIn July 2016, following major yellow fever (YF) outbreaks in two countries, WHO published a secretariat information paper including a review of studies assessing the immunogenicity of fractional doses of YF vaccines and recommended consideration of fractional doses to manage a vaccine shortage. Following this, fractional doses of YF vaccine produced by Bio-Manguinhos/Fiocruz (17DD substrain) were given to approximately 7.5 million non-pregnant adults and children ≥ 2 years of age in Kinshasa, Democratic Republic of Congo. The evidence base to support this action was limited to a single vaccine substrain and to a specific context. To broaden and simplify recommendations, WHO called for additional research to be conducted. We designed a trial to assess non-inferiority in seroconversion of fractional (one-fifth dose) versus standard dose for each of the four WHO-prequalified YF vaccines at 28 days post-vaccination in an adult population in Kenya and Uganda. We selected vaccine batches as close as possible to each manufacturer’s minimum release specification.Added value of this studyThis is the first randomized controlled trial assessing all four WHO-prequalified YF vaccines, providing information on the immunogenicity and safety of fractional doses of the different vaccine substrains at 10 days, 28 days and one year post-vaccination. The results show that, at 28 days post-vaccination, most participants had high levels of neutralizing antibodies and that seroconversion rates in the fractional dose arms were non-inferior to standard dose for each of the four vaccines. Seroconversion rates and neutralizing antibodies remained high up to one year post-vaccination for both fractional and standard doses for all vaccines. These results are aligned with previous studies using the 17DD substrain vaccine but extend the evidence to randomized comparisons of all four vaccines and to a sub-Saharan Africa context. To our knowledge, this is the first trial assessing immunogenicity of fractional doses at 10 days post-vaccination.Implications of all the available evidenceOur study supports the use of one-fifth fractional doses of all four WHO-prequalified yellow fever vaccines for the general adult population and fills a critical knowledge gap to support WHO policy on the use of fractional dosing of yellow fever vaccine for outbreak response. The immunogenicity and safety of fractional dosing in children and specific populations, such as those living with HIV, is yet to be determined. Long-term studies are warranted to confirm the duration of protection.

We used controlled human malaria infection (CHMI) to study naturally acquired immunity of Kenyan adults. We administered 3.2×103 cryopreserved Plasmodium falciparum sporozoites (SPZ, NF54 West African strain) and undertook clinical monitoring and serial quantitative PCR (qPCR). Of the 142 volunteers who were eligible for analysis: 26 (18.3%) had febrile symptoms and were treated; 30 (21.1%) reached ≥500 parasites/μl and were treated; 53 (37.3%) had parasitaemia without meeting thresholds for treatment and; 33 (23.2%) remained qPCR negative. We find that the immunity acquired by some Kenyan adults can completely suppress in vivo growth of a parasite strain originating from outside Kenya.

Background: Screening for Plasmodium spp. sporozoite infection in mosquitoes is routinely done using ELISA (enzyme-linked immunosorbent assay). Near infrared spectroscopy (NIRS), a fast and non-destructive method, has recently been shown to distinguish, with 95% accuracy, between uninfected and sporozoite-infected mosquitoes using laboratory strains of Plasmodium falciparum (PfN54). The aim of this present study was to further investigate the reproducibility of NIRS to identify sporozoite infection in mosquitoes infected using field isolates of P. falciparum gametocytes from asymptomatic carriers. Methods: Healthy individuals (aged 5 years and above) were screened for gametocytaemia by thick-smear microscopy in an area of moderate transmission along the Coast of Kenya between May and September 2018. Asymptomatic gametocyte carriers were recruited for mosquito feeding assays, direct membrane feeding (DMFA) and direct skin feeding (DFA), using insectary-reared Anopheles gambiae s.s (Kilifi strain). Mosquitoes were kept for 14-days post feeding after which they were scanned using NIRS and subsequently analysed for sporozoite infection using circumsporozoite-ELISA. Predictive models were explored using partial least square regressions (PLS).Results: Two hundred and ninety-nine (299) individuals were screened for malaria parasites, 74 (24.8%) were found with circulating asexual parasites, and 16 (5.4%) with P. falciparum gametocyte stages.Fourteen (14) asymptomatic gametocyte carriers were recruited to the study for mosquito feeding assays. A total of 134 (7%, 134/1881) sporozoite-infected mosquitoes were obtained from 9 successful experiments. Three different training datasets composed of infected and uninfected mosquitoes were analysed. The PLS models were unable to distinguish between sporozoite-infected and uninfected mosquitoes. A predictive model could not be generated.Conclusions: The results of this study were not consistent with previous published research on NIRS for detection of sporozoite infection in the same mosquito species and may reflect differences between laboratory and field conditions. The current findings indicate that methods for sporozoite detection should be tested on field isolates at an early stage in their development and are informative for future research seeking novel high-throughput methods for parasite detection in mosquitoes.

BackgroundScreening for Plasmodium spp. sporozoite infection in mosquitoes is routinely done using ELISA (enzyme-linked immunosorbent assay). Near infrared spectroscopy (NIRS), a fast and non-destructive method, has recently been shown to distinguish, with 95% accuracy, between uninfected and sporozoite-infected mosquitoes using laboratory strains of Plasmodium falciparum (PfN54). The aim of this present study was to further investigate the reproducibility of NIRS to identify sporozoite infection in mosquitoes infected using field isolates of P. falciparum gametocytes from asymptomatic carriers.MethodsHealthy individuals (aged 5 years and above) were screened for gametocytaemia by thick-smear microscopy in an area of moderate transmission along the Coast of Kenya between May and September 2018. Asymptomatic gametocyte carriers were recruited for mosquito feeding assays, direct membrane feeding (DMFA) and direct skin feeding (DFA), using insectary-reared Anopheles gambiae s.s (Kilifi strain). Mosquitoes were kept for 14-days post feeding after which they were scanned using NIRS and subsequently analysed for sporozoite infection using circumsporozoite-ELISA. Predictive models were explored using partial least square regressions (PLS).ResultsTwo hundred and ninety-nine (299) individuals were screened for malaria parasites, 74 (24.8%) were found with circulating asexual parasites, and 16 (5.4%) with P. falciparum gametocyte stages. Fourteen (14) asymptomatic gametocyte carriers were recruited to the study for mosquito feeding assays. A total of 134 (7%, 134/1881) sporozoite-infected mosquitoes were obtained from 9 successful experiments. Three different training datasets composed of infected and uninfected mosquitoes were analysed. The PLS models were unable to distinguish between sporozoite-infected and uninfected mosquitoes. A predictive model could not be generated.ConclusionsThe results of this study were not consistent with previous published research on NIRS for detection of sporozoite infection in the same mosquito species and may reflect differences between laboratory and field conditions. The current findings indicate that methods for sporozoite detection should be tested on field isolates at an early stage in their development and are informative for future research seeking novel high-throughput methods for parasite detection in mosquitoes.

Background: The life-saving role of oxygen therapy in children with clinically-defined severe pneumonia is not yet established. We hypothesised liberal oxygenation strategies and/or respiratory support may improve the high in-hospital mortality. Methods: The open-label fractional-factorial COAST trial in Ugandan and Kenyan children aged >28 days with feature of severe pneumonia. In stratum A (severe hypoxaemia: SpO2 3hours receipt of oxygen were excluded. The primary endpoint was 48-hour mortality; secondary endpoints included mortality or neurocognitive sequelae at 28 days. Findings: The Trial Steering Committee recommended halting recruitment for feasibility after 1842/4200 (44%) children enrolled. Of 1852 recruited, 388 in stratum A (median 7 months; median age SpO2 75%) were randomised to HFNT (n=194) or LFO (n=194) and 1454 in stratum B (median 9 months; median SpO2 88%) were randomised to HFNT (n=363) vs LFO (n=364) vs control (n=727). Per-protocol 109/726(15%) of controls received oxygen (when SpO2

Malaria remains a major public health burden despite approval for implementation of a partially effective pre-erythrocytic malaria vaccine. There is an urgent need to accelerate development of a more effective multi-stage vaccine. Adults in malaria endemic areas may have substantial immunity provided by responses to the blood stages of malaria parasites, but field trials conducted on several blood-stage vaccines have not shown high levels of efficacy. We will use the controlled human malaria infection (CHMI) models with malaria-exposed volunteers to identify correlations between immune responses and parasite growth rates in vivo. Immune responses more strongly associated with control of parasite growth should be prioritized to accelerate malaria vaccine development. We aim to recruit up to 200 healthy adult volunteers from areas of differing malaria transmission in Kenya, and after confirming their health status through clinical examination and routine haematology and biochemistry, we will comprehensively characterize immunity to malaria using >100 blood-stage antigens. We will administer 3,200 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (PfSPZ Challenge) by direct venous inoculation. Serial quantitative polymerase chain reaction to measure parasite growth rate in vivo will be undertaken. Clinical and laboratory monitoring will be undertaken to ensure volunteer safety. In addition, we will also explore the perceptions and experiences of volunteers and other stakeholders in participating in a malaria volunteer infection study. Serum, plasma, peripheral blood mononuclear cells and whole blood will be stored to allow a comprehensive assessment of adaptive and innate host immunity. We will use CHMI in semi-immune adult volunteers to relate parasite growth outcomes with antibody responses and other markers of host immunity. Registration: ClinicalTrials.gov identifier NCT02739763.

Background: Zika virus (ZIKV) was first discovered in East Africa in 1947. ZIKV has caused microcephaly in the Americas, but it is not known whether ZIKV is a cause of microcephaly in East Africa. Methods: We used surveillance data from 11,061 live births at Kilifi County Hospital in coastal Kenya between January 2012 and October 2016 to identify microcephaly cases and conducted a nested case-control study to determine risk factors for microcephaly. Gestational age at birth was estimated based on antenatal ultrasound scanning (‘Scanned cohort’) or last menstrual period (‘LMP cohort’, including births ≥37 weeks’ gestation only). Controls were newborns with head circumference Z scores between >-2 and ≤2 SD that were compared to microcephaly cases in relation to ZIKV exposure and other maternal and newborn factors. Results: Of the 11,061 newborns, 214 (1.9%, 95%CI 1.69, 2.21) had microcephaly. Microcephaly prevalence was 1.0% (95%CI 0.64, 1.70, n=1529) and 2.1% (95%CI 1.81, 2.38, n=9532) in the scanned and LMP cohorts, respectively. After excluding babies Conclusions: Microcephaly was prevalent in coastal Kenya, but does not appear to be related to ZIKV exposure; the ZIKV response observed in our study population was largely due to cross-reactive responses to DENV or other related flaviviruses. Further research into potential causes and the clinical consequences of microcephaly in this population is urgently needed.