INTRODUCTION:Breathlessness is a common cause of hospital admission globally and is associated with high mortality, particularly in low-income countries. In sub-Saharan Africa, there is a paucity of data on breathlessness, with existing data focused on individual diseases. There is a need for patient-centred approaches to understand interactions between multiple conditions to address population needs and inform health system responses. This multicentre prospective study in Malawi aimed to characterise the aetiologies, outcomes and biomarker accuracy for breathless patients. METHODS:Adults (aged ≥18 years) admitted to medical wards were consecutively recruited within 24 hours of hospital presentation and followed up for 1 year. Participants with breathlessness (defined as a composite of patient-reported shortness of breath; tachypnoea (respiratory rate ≥25/min); hypoxaemia (SpO2 <94%) or treatment with oxygen) were systematically screened against internationally accepted diagnostic criteria. We estimated disease prevalence, survival, health-related quality of life and functional status. We also evaluated diagnostic accuracy of natriuretic peptides for heart failure, and procalcitonin (PCT) and C reactive peptide (CRP) for pneumonia. RESULTS:Of 751 participants, 44% (n=334) had breathlessness, and 316 underwent enhanced diagnostic screening. One-year mortality was higher in breathless patients (51% (157/307)) than those without (26% (100/385)); adjusted HR 1.8 (95% CI 1.4 to 2.3). We identified high prevalence and mortality of heart failure (35% (112/316) prevalence; 69% (75/109) 1-year mortality), anaemia (40% (126/316); 57% (70/122)), pneumonia (41% (131/316); 53% (68/129)) and tuberculosis (29% (91/316); 47% (41/87)). Most participants (63% (199/316)) had multiple conditions. Diagnostic accuracy (area under the curve) for heart failure was 0.89 (brain natriuretic peptide) and 0.88 (N-terminal pro-B-type natriuretic peptide); for pneumonia, CRP was 0.77 and PCT was 0.69. DISCUSSION:Breathlessness-related hospital admissions in Malawi are common, multifactorial and associated with poor survival. This study demonstrates that co-existing conditions are common, highlighting the limitation of single-disease-focused health system responses. Integrated care pathways with context-sensitive diagnostic and treatment approaches are urgently needed to improve survival.

Shared leadership between global and African partners is essential to expand early-phase trial capacity in sub-Saharan Africa and ensure that medical innovation serves the populations most affected by disease.

Background: Bacterial mucosal immunotherapy has shown protection of children and adults from both viral and bacterial respiratory infections, offering the potential to reduce antimicrobial use, and hence also control antimicrobial resistance (AMR). Pneumococcal carriage of vaccine type S. pneumoniae remains high in Malawi despite infant conjugate vaccination and AMR is increasing. We compared nasal inflammation following sublingual bacterial immunotherapy (MV130, Immunotek, Spain) or placebo and determined the effect in an experimental human pneumococcal carriage model. Methods: A double-blind, randomized, placebo-controlled trial in healthy adult volunteers was conducted at Queen Elizabeth Central Hospital in Blantyre, Malawi. Participants were randomly allocated to receive MV130 or placebo sublingually once daily for 42 days. Mucosal inflammation (neutrophil to T cell ratio) was measured in nasal micro-biopsies. Post-treatment, participants were challenged with 80,000 CFU/naris Streptococcus pneumoniae 6B (SPN6B). Experimental pneumococcal carriage rates post inoculation were compared between the two arms. All participants completing the study were included in the analysis. Trial Registration: Pan African Clinical Trial Registry: PACTR202403820001276. Findings: 107 participants were enrolled and randomized to MV130/placebo between May and December 2024. There were no serious adverse events, and all adverse events were mild. 96 participants (53 male, 43 female) completed the study with 52 participants randomized to MV130 and 44 to placebo. There was no difference in mucosal inflammation (neutrophil to T cell ratio) at day 14 with the intervention MV130 NTR median = 0.737 (IQR 0.294,2.059) and placebo NTR = 0.831 (IQR 0.450,2.073), p=0.64. On day 35 of MV130 treatment NTR median=1.565 compared to placebo NTR=0.820, p=0.01. There was no difference in experimental pneumococcal carriage proportion between MV130 (12/52, 23%) and placebo (10/44, 23%) groups (p=1.0). Interpretation: MV130 induced mild neutrophil inflammation of the nasal mucosa but had no protective effect against experimental human pneumococcal carriage.

Background Individuals with asthma have increased susceptibility to bacterial pneumonia, potentially related to altered mucosal immunity and corticosteroid therapy. Cross-sectional studies suggest higher rates of Streptococcus pneumoniae (pneumococcus) carriage in asthma, but the dynamics of colonisation and mucosal immune mechanisms remain unclear. Methods We assessed 50 participants with well-controlled asthma (on moderate inhaled corticosteroid therapy) and 151 healthy controls, all experimentally challenged with type 6B pneumococcus. A subset of asthma participants (n=12) who became colonised were rechallenged 6-11 months later with the same pneumococcal isolate. Colonisation rates (from nasal wash), systemic antibody levels and mucosal cellular and cytokine responses were compared between groups. Results The colonisation rates were 56% (28/50) in asthma participants and 45% (68/151) in controls (p=0.17). The median duration of colonisation was shorter in asthma participants (14 days, IQR 7–29) compared with controls (29 days, IQR 14–29, p=0.034), although bacterial densities were similar between both groups. Despite an increase in pneumococcus-capsule-specific antibodies following colonisation, 4/12 asthma participants were recolonised after rechallenge. Nasal neutrophil and T cell frequencies, particularly mucosa-associated invariant T cells, were lower in asthma participants compared with healthy controls before challenge. Similarly, 22 out of 30 measured mucosal cytokines were significantly lower at baseline in asthma participants. Despite these deficits, both groups exhibited similar recruitment of monocytes and granulocytes to the nasal mucosa following colonisation. Conclusions Adults with asthma demonstrate reduced mucosal immune tone and impaired development of protection against pneumococcal recolonisation, despite preserved innate recruitment and generation of pneumococcal-specific antibodies. These findings identify distinct mucosal immune alterations in asthma that may underlie persistent susceptibility to pneumococcal infection and inform strategies for targeted vaccination and immune modulation. Trial registration number ISRCTN16755478 .

Nasopharyngeal colonisation with Streptococcus pneumoniae is a prerequisite for transmission and disease and represents an important immunising event. While colonisation induces serotype-specific immunity, the mechanisms underlying heterologous protection remain unclear. We developed a controlled human infection model using pneumococcal serotype 15B and investigated colonisation dynamics, immunogenicity, and cross-protection against subsequent heterologous challenge with serotype 6B. Fifty-four healthy adults were intranasally inoculated with 15B at escalating doses. Colonisation rates peaked at 31.4% with 8 x 10⁴ CFU per naris, lower than those historically observed with 6B and 3 strains. Density was also lower than previously observed with other strains. In vitro assays demonstrated that 15B adhered more readily to epithelial cells than 6B, but was less efficiently internalised, potentially reducing attack rates and colonisation density. Colonisation with 15B induced capsular polysaccharide-specific serum IgG, but baseline humoral immune measures did not predict protection from acquisition. Prior colonisation with 15B did not reduce acquisition of 6B upon re-challenge. Analysis of nasal microbiopsy samples revealed distinct innate activation signatures. Resistance to colonisation was associated with elevated baseline MIP-1α and MIP-1β responses upon in vitro stimulation, whereas carriage was associated with enhanced chemokine and IL-6 responses. Local innate immune activation, rather than circulating antibody responses alone, may therefore contribute to colonisation control. We demonstrate that experimental colonisation with 15B does not confer heterologous protection against 6B and highlight the importance of mucosal innate immune conditioning in serotype-independent defence. Strategies enhancing nasal innate immune recruitment and activation may be required for broader protection against pneumococcal colonisation. ### Competing Interest Statement RM is a consultant to GSK and Merck, is a named inventor and patent holder on vaccine technologies, a member of the board of directors at Corner Therapeutics and the scientific advisory boards of Amplitude Therapeutics, Limmatech and Vitrivax. Y-JL is a named inventor and patent holder on vaccine technologies. All the other authors have declared that no conflicts of interest exist. ### Clinical Trial ISRCTN68323432 ### Clinical Protocols ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All participants gave informed written consent. Ethics committee of the National Health Service Research Ethics Committee, Liverpool East gave ethical approval for this work (15/NW/0931) and the trial was registered with ISRCTN (Trial Registration Number: [ISRCTN68323432][1]). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data are available upon reasonable request by email directed to the corresponding authors at daniela.ferreira{at}paediatrics.ox.ac.uk and carla.solorzanogonzalez{at}paediatrics.ox.ac.uk. Medical Research Council, https://ror.org/03x94j517, MR/M011569/1 [1]: /external-ref?link_type=ISRCTN&access_num=ISRCTN68323432

BACKGROUND:Bacterial mucosal immunotherapy has shown protection of children and adults from both viral and bacterial respiratory infections, offering the potential to reduce antimicrobial use, and hence also control antimicrobial resistance (AMR). Pneumococcal carriage of vaccine type Streptococcus pneumoniae remains high in Malawi despite infant conjugate vaccination and AMR is increasing. We compared nasal inflammation following sublingual bacterial immunotherapy including S. pneumoniae (MV130, Inmunotek, Spain) or placebo and determined the effect in an experimental human pneumococcal carriage model. METHODS:A double-blind, randomised, placebo-controlled trial in healthy adult volunteers was conducted at Queen Elizabeth Central Hospital in Blantyre, Malawi. Participants were randomly allocated to receive MV130 or placebo sublingually once daily for 42 days. Mucosal inflammation (neutrophil to T cell ratio, NTR) was measured in nasal micro-biopsies. Post-treatment, participants were challenged with 160,000 CFU/naris S. pneumoniae 6B (Spn6b). Experimental pneumococcal carriage rates post inoculation were compared between the two arms. All participants completing the study were included in the analysis. Prospective trial registration: PACTR202403820001276. FINDINGS:107 participants were enrolled and randomised to MV130/placebo between May and December 2024. There were no serious adverse events, complete compliance was good (72%) and all adverse events were mild. 96 participants (53 male, 43 female) completed the study with 52 participants randomised to MV130 and 44 to placebo. There was no difference in mucosal inflammation (neutrophil to T cell ratio) at day 14 of the intervention MV130 NTR median = 0.737 (IQR 0.294, 2.059) and placebo NTR = 0.831 (IQR 0.450, 2.073), p = 0.64. Secondary analyses showed a rise in mucosal neutrophils after MV130 treatment and after experimental pneumococcal inoculation. There was no difference in nasal or serum anti-pneumococcal immunoglobulin or in experimental pneumococcal carriage proportion between MV130 (12/52, 23%) and placebo (10/44, 23%) groups (unadjusted risk ratio 1.02 (CI 0.49-2.12) p = 1.0). INTERPRETATION:MV130 induced non-specific mild neutrophil inflammation of the nasal mucosa but had no protective effect against experimental human pneumococcal carriage. FUNDING:Wellcome Trust.

Background: People living with HIV (PLHIV) in sub-Saharan Africa exhibit high rates of pneumococcal carriage compared to HIV-uninfected adults, despite antiretroviral therapy. We established a novel controlled human infection model of experimental pneumococcal carriage in people living with HIV to understand carriage dynamics in this at-risk population. Methods: Seventy-five virally suppressed and clinically stable PLHIV and 75 HIV-uninfected controls were inoculated with escalating doses of pneumococcus serotype 6B. Carriage acquisition and density were determined by microbiological culture of nasal wash samples collected before and up to 14 days after inoculation. Adverse events were identified by active and passive surveillance. Participant-reported acceptability was established using a Likert scale. Findings: No serious adverse events occurred. Mild adverse events were similar between groups (19% [14/75] in PLHIV, 13% [10/75] in HIV-uninfected; p=0.505). More than 90% of participants reported acceptability with all study procedures. Experimental carriage occurred in 21% (16/75) of PLHIV compared with 36% (27/75) of HIV-uninfected participants (adjusted odds ratio 0.39 [95% CI 0.16-0.91]). Among PLHIV without detectable cotrimoxazole, 28% (8/29) acquired experimental carriage. Carriage clearance rates were lower in PLHIV (hazard ratio 0.44 [95% CI 0.14-1.42]). Interpretation: In carefully selected PLHIV with effective viral suppression and clinical stability experimental pneumococcal carriage acquisition did not exceed that in HIV-uninfected adults, even after accounting for antibiotic use, natural pneumococcal co-colonisation, and sociodemographic differences. These findings suggest that high carriage prevalence in PLHIV in sub-Saharan Africa may be driven more by prolonged carriage duration than increased susceptibility to acquisition. This model provides a platform to investigate mechanisms underlying carriage susceptibility and impaired clearance in PLHIV and to evaluate interventions aimed at reducing the carriage burden in sub-Saharan Africa. Funding: Wellcome Trust ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT05698225 ### Funding Statement This work was supported by a Wellcome clinical PhD fellowship (226731/Z/22/Z) held by KD and a Wellcome grant for Malawi Accelerated Research in Vaccines, Experimental and Laboratory Systems (211433/Z/18/Z) held by SG. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethical approval was granted by the Malawian National Health Science Research Committee (NHSRC) (22/09/3053) and by Liverpool School of Tropical Medicine Research Ethics Committee (22-077). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data from this study is available on request from the authors.

Controlled Human Infection Models (CHIM) in which volunteers are experimentally exposed to pathogens are used to study pathogenesis and down select among treatment and vaccine candidates. Scientifically, CHIM studies are best conducted among at-risk populations in which the infection is endemic, and who are likely to benefit from new interventions tested. Ethically, the perspectives of these communities should be carefully considered in designing such research. CHIM studies are often conducted among healthy adults, but we wished to understand study participant’s and community views on conducting CHIM studies in groups other than healthy adults, particularly people living with HIV (PLHIV). We also wished to explore community perceptions of a tuberculosis CHIM (TB CHIM), initially using Bacillus Calmette Guerin (BCG) as a safe intermediate step. We conducted fourteen focus group discussions (FGD) and eight in-depth interviews (IDI) among a wide range of stakeholders including participants, health workers, community advisory groups, religious leaders and medical opinion leaders in Malawi. Discussions and interviews were recorded, transcribed and analysed using thematic and framework analysis. Four themes were described in the data, showing engaged stakeholder acceptance of CHIM studies, and confidence in the research practice and motivation. In the specific examples discussed in this work at-risk populations specifically PLHIV and complex pathogens specifically TB-CHIM, there was concern for safety, proper consent and community consultation. In addition, cultural views on gender roles in Malawi, tissue sampling and residential stays for research study were discussed. Overall, there was support for CHIM among PLHIV, and CHIM working through a BCG CHIM towards safe TB CHIM in future. Appropriate safety caveats and regulatory measures were suggested. Advice on wide, public awareness campaign methods was offered to researchers.

Identifying conserved, immunogenic proteins that confer protection against Streptococcus pneumoniae (pneumococcus) colonization could enable development of serotype-independent vaccines. In our controlled human infection model, no individual IgG or cytokine/chemokine response correlated significantly with protection against colonization with pneumococcus, suggesting that effective immunity reflects a coordinated, multi-antigen response. To capture these complex patterns, we trained independent Random Forest models on humoral and cellular datasets. The humoral model identified IgG responses to PdB, SP1069, and SP0899 as predictive of protection. The cellular model revealed that MCP-1 responses to SP1069 and SP0899, and IL-17A production in response to SP0648-3, were associated with protection. Elevated baseline IFN-γ, RANTES, and anti-protein IgG levels were linked to reduced colonization density. We highlight SP1069 and SP0899 as potential serotype-independent vaccine candidates and demonstrate the utility of machine learning to identify immune correlates of protection.

Controlled human infection models (CHIMs) can accelerate vaccine development for infectious diseases. Mycobacterium tuberculosis is a human-adapted pathogen that is the leading infectious cause of death worldwide. M tuberculosis infection results in a spectrum of clinical outcomes that are incompletely modelled in animals. To date, the risks of infection, prolonged treatment, and sequelae related to CHIMs with M tuberculosis have been considered ethically unacceptable. However, recent advances in bacterial engineering have resulted in safe strains that could permit M tuberculosis CHIM studies with reduced risks. In this Personal View, we address the practical considerations for conducting a pulmonary M tuberculosis CHIM study. We summarise the ethical issues of M tuberculosis CHIM studies in tuberculosis-endemic and non-endemic settings; describe safety considerations, such as optimising the challenge dose and minimising risks to third parties; and outline and prioritise clinical, microbiological, immunological, and radiological endpoints that would render such a model useful for vaccine development.

We conducted the first pooled analysis of two randomised controlled vaccine trials on experimental pneumococcal serotype 6B carriage, registered in Malawi (PACTR202008503507113) and the UK (ISRCTN45340436). This post-hoc exploratory study examined the sex-based differences in carriage, vaccine efficacy and vaccine-induced responses. PCV-13 reduced colonisation by 76% (p < 0.001) with non-significant interaction by sex (RR = 1.549, p = 0.413). Females showed a higher carriage rate than males (28% vs. 19%, p = 0.066). Baseline anti-6B Capsular Polysaccharide Immunoglobulin G (IgG) titres were higher in females, significantly in Malawi (2.62 µg/ml vs males 2.05 µg/ml, p = 0.015). Post-vaccination titres did not differ by sex. The pooled fold change in IgG pre-post vaccination, was higher in vaccinated females (5.47 vs 3.30, p = 0.053). This analysis demonstrates the utility and challenges of integrating CHIM data between diverse settings to evaluate vaccine efficacy, describe inter-setting differences, investigate biological and immunological factors influencing protection against pneumococcal carriage and ultimately inform future vaccine development strategies.

BACKGROUND:In Malawi, childhood pneumococcal conjugate vaccination has not achieved expected herd protection despite the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) in 2011. Vaccine efficacy and longevity of protection are crucial in achieving herd protection. We previously found that PCV13 offers immediate protection from experimental pneumococcal carriage in Malawian adults, but of uncertain duration. In this follow-up study, we aimed to evaluate the longevity of protection of PCV13 vaccination against experimental human pneumococcal carriage measured by 1-year post-vaccination homotypic Streptococcus pneumoniae serotype 6B (Spn6B) rechallenge in healthy Malawian adults. METHODS:We previously conducted a double-blind, parallel-arm, randomised controlled trial investigating the efficacy of PCV13 or placebo against Spn6B carriage in healthy adults (aged 18-40 years) in Blantyre, Malawi. This longitudinal follow-up study re-recruited all eligible participants available at 1 year post-vaccination. Eligibility criteria for participation remained the same as those for the initial trial. Individuals with safety concerns, including those at increased risk of invasive pneumococcal disease or with close contacts at risk, were excluded from study participation. Participants with natural carriage other than Spn6B were included in the study. Participants were rechallenged intranasally with 80 000 colony-forming units of Spn6B per naris. The primary endpoint was experimental pneumococcal carriage, established by culture of nasal wash samples collected at days 2, 7, and 14 after rechallenge, and was assessed in all participants who received the rechallenge inoculation. The original trial was registered with the Pan African Clinical Trial Registry (PACTR202008503507113) and is closed. FINDINGS:Participants were re-recruited from May 10, 2022, to Aug 22, 2023. 137 participants (77% male; median age 26 years [IQR 23-29]) were re-recruited (57 PCV13 and 80 placebo) and completed the study protocol. In the log-binomial adjusted model, vaccine protection on the probability of Spn6B carriage following rechallenge was 73% (relative risk [RR] 0·27, 95% CI 0·08-0·98, p=0·047). Previous experimental Spn6B carriage reduced the vaccine protective effect (RR 2·20, 0·85-5·67, p=0·10). The effect of PCV13 vaccination was reduced within previous Spn6B carriers (RR 8·95, 2·27-35·33, p=0·002) and previous natural pneumococcal carriers (RR 14·31, 1·65-124·20, p=0·016). INTERPRETATION:The study indicates that PCV13 vaccination has a role in preventing pneumococcal carriage for at least 1 year, showing strong interactions with natural carriage events. These findings suggest that the inability to achieve herd protection in Malawi is probably due to factors other than the efficacy or duration of protection of the PCV13 vaccine. FUNDING:Wellcome Trust.

BACKGROUND:Although evidence suggests some direct protection from the 13-valent pneumococcal conjugate vaccine (PCV13) against Streptococcus pneumoniae serotype 3 (Spn3), Spn3 remains a frequent cause of pneumococcal disease in the UK, potentially due to lower vaccine effect on colonisation, shorter duration of protection, or the emergence of more successful Spn3 clades. To test these hypotheses, we compared PCV13 and 23-valent pneumococcal polysaccharide vaccine (PPV23) protection against prevalent Spn3 clades. Additionally, we assessed the long-term protection offered by pneumococcal vaccines against colonisation using S pneumoniae serotype 6B (Spn6B), a serotype PCV13 protects against in the short term. METHODS:This double-masked, randomised, controlled, phase 4 trial recruited healthy participants aged 18-50 years in Liverpool, UK, and assigned them (2:1:2) to PCV13, PPV23, or placebo (0·9% NaCl). Participants assigned to the PPV23 group were challenged with clade Iα, and participants in PCV13 and placebo groups were subsequently randomly assigned to receive clade Iα or II Spn3. Nasal challenge with Spn3 was at 1 month and with Spn6B in a subgroup at 6 months after vaccination. Selection for this subgroup was conducted on a first-come-first-served basis, with participants who enrolled earliest being offered participation in both challenges. Recruitment for the second challenge was discontinued once the target number of participants was reached. The primary outcome was the acquisition risk of the challenge strain as detected by nasal wash culture at 2 days, 7 days, 14 days, or 23 days in the vaccine versus the placebo groups. The analysis was performed in a modified intention-to-treat population, defined as all participants who received vaccination, underwent challenge, and had at least one nasal wash sample collected after the challenge. Randomisation used a computer-generated schedule that only the unmasked team could access. The unmasked team performed vaccinations and did not perform the nasal challenges or nasal washes. The laboratory staff and participants were masked to the vaccination status. This study was prospectively registered with the EU Drug Regulating Authorities Clinical Trials Database, 2019-004742-15, the International Standard Randomised Controlled Trial Number registry, ISRCTN15728847, and ClinicalTrials.gov, NCT04974294, and is complete. FINDINGS:This trial was conducted between July 28, 2021, and Oct 3, 2023. The analysis included 407 participants challenged with Spn3 and 243 challenged with Spn6B. 1 month after vaccination, PCV13 was associated with a non-significant reduction (16%) in Spn3 colonisation acquisition when considering both clades combined(84 [56%] of 153 participants in the PCV13 group vs 101 [65%] of 155 in the placebo group; relative risk 0·84, 95% CI 0·70-1·01; p=0·068). PCV13 was moderately protective (29%) against clade II (0·71, 0·54-0·91; p=0·0090) but was not protective against clade Iα (1·01, 0·77-1·32; p=0·95). No evidence of protection from PPV23 vaccination was found against clade Iα (0·84, 0·63-1·11; p=0·22). At 6 months, PCV13 showed a 60% relative risk reduction against Spn6B (0·40, 0·22-0·69; p=0·0020) with no evidence of protection from PPV23 (0·90, 0·60-1·34; p=0.60). There were no severe or life-threatening adverse events. INTERPRETATION:Our findings indicate partial direct protection by PCV13 against Spn3 colonisation acquisition, with differential protection against the clades and no protection by PPV23 against clade Iα. By contrast, PCV13 protected against Spn6B colonisation for at least 6 months. These findings align with epidemiological evidence, indicating that, although PCV13 vaccination against Spn6B offers sustained direct and indirect protection, its effect on Spn3 colonisation and therefore indirect protection is limited. Direct vaccination of at-risk adults might therefore be more appropriate than relying solely on herd immunity from paediatric programmes. The development of next-generation pneumococcal vaccines and further immunological analysis are needed to optimise protection against Spn3. FUNDING:Pfizer.

Stroke incidence is rising rapidly in low- and middle-income countries (LMICs), particularly in sub-Saharan Africa, yet access to organised stroke care remains extremely limited. Although stroke units are among the most effective and cost-efficient interventions for improving outcomes after stroke, implementation in resource-constrained settings remains challenging. We describe the development of the first dedicated stroke unit in Malawi, established in 2022 at Queen Elizabeth Central Hospital (QECH), Blantyre. The QECH Comprehensive Stroke Service (QSS) was developed through a partnership involving the Malawi Ministry of Health, QECH, Malawi-Liverpool-Wellcome Research Programme (MLW), Kamuzu University of Health Sciences (KUHeS), University College London Hospitals (UCLH), and academic collaborators in Malawi and the UK. This paper focuses on health-system development rather than clinical outcomes. We describe the processes underpinning implementation, including partnership building, workforce development, infrastructure creation, pathway design, governance, and integration of data systems. Existing research infrastructure provided a foundation for service evaluation, registry development, and future interventional studies. Key lessons from the first three years included the importance of strong nursing leadership, task-shifting, phased implementation, multidisciplinary mentorship, and early alignment with Ministry of Health priorities in addressing workforce shortages and limited specialist capacity. Dedicated clinical space and integration with surveillance and research infrastructure supported sustainability, while weak digital systems and service overload remained ongoing challenges. Our experience demonstrates that organised stroke services can be developed in LMIC settings through adaptive clinical–academic partnerships integrated within existing health systems.

BACKGROUND:Non-traumatic coma in African children is a common life-threatening presentation often leading to hospital attendance. We aimed to estimate the distribution of non-traumatic coma causes and outcomes, including disease-specific outcomes, for which evidence is scarce. METHODS:We systematically reviewed MEDLINE, Embase, and Scopus databases from inception to Feb 6, 2024. We included studies recruiting children (aged 1 month to 16 years) with non-traumatic coma (Blantyre Coma Scale score ≤2, ie deep coma or comparable alternative) from any African country. Disease-specific studies were included if outcomes were reported. Primary data were requested where required. We used a DerSimonian-Laird random effects model to calculate pooled estimates for prevalence of causes, mortality, and morbidity (in-hospital and post-discharge), including analysis of mortality by temporality. This study was registered with PROSPERO (CRD4202014193). FINDINGS:We screened 16 666 articles. 138 studies were eligible for analysis, reporting causes, outcome data, or both from 35 027 children with non-traumatic coma in 30 African countries. 114 (89%) of 128 studies were determined to be high quality. Among the causes, cerebral malaria had highest pooled prevalence at 58% (95% CI 48-69), encephalopathy of unknown cause was associated with 23% (9-36) of cases, and acute bacterial meningitis was the cause of 10% (8-12) of cases, with all other causes representing lower proportions of cases. Pooled overall case-fatality rates were 17% (16-19) for cerebral malaria, 37% (20-55) for unknown encephalopathy, and 45% (34-55) for acute bacterial meningitis. By meta-regression, there was no significant difference in cerebral malaria (p=0·98), acute bacterial meningitis (p=0·99), or all-cause coma (p=0·081) mortality by year of study. There was no substantial difference in deaths associated with cerebral malaria in-hospital compared with post-discharge (17% [16-19] vs (18% [16-20]). Mortality was higher post-discharge than in-hospital in most non-malarial comas, including acute bacterial meningitis (39% [26-52]) vs 53% [38-69]). Disability associated with cerebral malaria was 11% (9-12). Pooled disability outcomes associated with other non-malarial diseases were largely absent. INTERPRETATION:The prevalence and outcomes of cerebral malaria and meningitis associated with non-traumatic coma were strikingly static across five decades. Enhanced molecular and radiological diagnostics, investment, policy making, community awareness, and health service provision are all required to facilitate earlier referral to specialist centres, to drive a step-change in diagnostic yield and treatment options to improve these outcomes. FUNDING:Wellcome Trust. TRANSLATIONS:For the Chichewa, French and Portuguese translations of the abstract see Supplementary Materials section.

Rationale: Oxygen is a World Health Organization (WHO) essential medicine and is the cornerstone of care for patients with hypoxemia of any cause. It is inadequately available in many resource-constrained settings. Tertiary hospitals in Malawi relied on oxygen concentrators and cylinders until 2020, when the COVID-19 crisis necessitated installation of oxygen plants. Prior to oxygen plant construction, only 30% of medical patients at Queen Elizabeth Central Hospital (QECH), Blantyre, who required oxygen were appropriately treated. It is likely that the high mortality seen in hypoxemic patients in these settings was at least in part attributable to the lack of available oxygen. We wished to audit the use and impact of medical oxygen in QECH, after the installation of piped oxygen. Methods: We conducted a prospective audit of the oxygen used at QECH beginning in January 2023 and compared this with plant capacity. Monthly oxygen supply was calculated by adding the daily production reports from the oxygen plant. Monthly oxygen demand was estimated by performing cross-sectional surveys of all oxygen devices in use one to three times per week and using the delivery device-specific formulas on oxygencalculator.org. We also conducted a prospective audit of all patient admissions from January 2023 to April 2024 to investigate mortality outcomes for adult patients with hypoxemia. Results: From January 2023 to January 2024, the oxygen plant was functioning, and there were no constraints on providing oxygen therapy to patients, primarily through piped oxygen. The oxygen plant was utilized at an average capacity of 56% (18 million liters per month out of 32 million liters per month capacity). From January 2023 to April 2024, we screened all 7,878 adult admissions, of which 6% (461) were hypoxemic on admission. Of the hypoxemic patients, 19% (89) were not receiving appropriate oxygen therapy at the time of screening, with SpO2 <90%. Forty percent of hypoxemic patients died during their hospitalisation. Conclusion: Despite improving access to oxygen therapy at QECH, not all patients receive therapeutic oxygen, and in-hospital mortality of patients with hypoxemia is still very high. This points to the urgent need to study and implement interventions beyond oxygen supply to improve survival. Our critical care research network is currently implementing a clinical trial (BREATHE trial: NCT05754034) where we are investigating the implementation of protocolised oxygen therapy as well as testing the feasibility and effectiveness of high flow oxygen therapy.

Background: Controlled Human Infection Models (CHIM) are an important tool in biomedical research in which pathogens are inoculated into human volunteers to study pathogenesis and test vaccines or treatments. Production of CHIM inoculum, however, presents specific challenges in safety, reproducibility and replication of the desired dose. The principles of Good Manufacturing Practice (GMP) developed for production of medications can be applied to the preparation of CHIM inocula, but licensed GMP facilities are scarce in low resource settings. Methods: We applied GMP principles to develop protocols for CHIM inocula production at Liverpool School of Tropical Medicine, UK and subsequently at Malawi-Liverpool Wellcome Programme, Malawi. We used published guidelines to evaluate these protocols and to advise selection, characterisation, manufacture, quality control and storage. We established in-house production of Streptococcus pneumoniae serotypes 3 and 6B for use in Experimental Human Pneumococcal Challenge models. Results: The manufacturing process underwent regulatory review in both the UK and Malawi. CHIM inocula production in Malawi was approved by the National Health Sciences Research Committee after written and oral submission. We successfully implemented our procedure and manufactured batch lots of Streptococcus pneumoniae serotype 3 (n = 2) and serotype 6B (n = 2). We safely, accurately and successfully inoculated participants in CHIM studies and achieved experimental human pneumococcal carriage with both serotype strains. Discussion: CHIM inoculum manufacture of pneumococcus was feasible in Malawi. This allowed the Malawi scientific ecosystem to demonstrate scientific and regulatory autonomy as well as having the potential to improve operational efficiency compared to importation of challenge agents.

BACKGROUND:Mucosal inflammation is associated with increased nasal pneumococcal colonisation, but the specific mechanisms are not fully understood. We aimed to find innate immune factors associated with pneumococcal carriage using a controlled human infection model. METHODS:Healthy Malawian adults participating in a randomised trial of pneumococcal conjugate vaccine (PCV13) were inoculated with one of three doses of Streptococcus pneumoniae 6B. We categorised the participants into 4 pneumococcal carriage outcome groups - no carriage; natural carriage; experimental carriage; and dual carriage. We then measured neutrophil to lymphocyte ratio (NLR) in nasal mucosa and cytokine levels in nasal lining fluid at 7 days before and 2, 7 and 14 days after inoculation. FINDINGS:We found that 45 % of participants had no carriage, 35 % had natural carriage, 12 % experimental carriage and 8 % dual carriage. At 2- and 7-days post inoculation, all groups showed an increase in NLR compared to 7 days before inoculation, accompanied by small changes in cytokine levels. An early increase in NLR was associated with protection against experimental carriage while cytokines did not associate with carriage pattern. CONCLUSION:Nasal inoculation with S. pneumoniae 6B induced mild, mucosal inflammation but established carriage was not pro-inflammatory. This suggests that nasal inoculation as a vaccine strategy could be asymptomatic.

Background Human infection studies (HIS) also known as Controlled Human Infection Models (CHIM) are a relatively new concept in African countries to clinicians, scientists, and communities alike. We have introduced HIS/CHIM studies to Malawi during the last four years by developing an experimental human pneumococcal carriage model. This CHIM was used to test the efficacy of a licensed 13-valent Pneumococcal Conjugate Vaccine (PCV13) against experimental nasal pneumococcal carriage. Traditional and digital recruitment strategies into this novel trial were explored. Objectives To describe various methods of recruitment in this first CHIM study in Malawi. Methods The clinical trial within the context of which these data were recorded was registered with the Pan African Clinical Trials Registry (REF: PACTR202008503507113) on 03 August 2020. The project was conducted at the Malawi Liverpool Wellcome Programme (MLW) in Blantyre, Malawi between April 2021, and September 2022. Source populations were college students and community members within Blantyre. Recruitment strategies included sharing study information in written or visual form, community sensitization meetings, snowball contacts (word of mouth from previous volunteers), branded clothing and participating in radio and television programs. Results 299 volunteers attended screening clinic, of whom 278 were recruited. Sixty-six recruited volunteers (23.7%) were college students and 212 (76.3%) were from the community. Snowball word-of-mouth contacting was the most successful recruitment strategy, with 201 (72.3%) participants recruited using this method. 195 (70.1%) were men of whom 149 (76.4%) joined the study through snowballing. Conclusion or recommendation Using a variety of recruitment strategies led to successful recruitment in this novel controlled human infection study. Most participants were recruited through snowballing.