AIMS:Parenteral artesunate is the preferred first-line treatment for severe malaria. Pre-referral rectal artesunate suppositories are recommended where parenteral treatment is inaccessible. In this study, we compared dihydroartemisinin exposure and model-predicted early parasite clearance following rectal artesunate and intravenous artesunate in African children with severe malaria. METHODS:A total of 82 African children with severe malaria participated in a randomized crossover study in Democratic Republic of Congo. Forty children received rectal artesunate (10 mg/kg) while the other 42 received intravenous artesunate (2.4 mg/kg) as the first intervention, and then the other route of administration for the second dose. Blood samples were drawn for drug quantification, and nonlinear mixed-effects modelling was used to evaluate the pharmacokinetic properties of intravenous and rectal artesunate and to simulate expected parasite clearance associated with these routes of administration. RESULTS:The mean individually estimated rectal bioavailability of artesunate was 21% but was highly variable (IQR: 8%-35%). Plasma exposure to dihydroartemisinin-the principal and bioactive metabolite of artesunate-did not differ significantly between rectal and intravenous administration. Predicted parasite reduction over the first 12 h was similar for both routes, consistent with previously reported clinical benefits of rectal artesunate. CONCLUSIONS:These findings support the 10-mg/kg dose of rectal artesunate as a pre-referral intervention, which should be more widely deployed in malaria-endemic areas.

Unlike peripheral blood parasitaemia, plasma concentrations of PfHRP2 has been established as a measure of total body parasite burden in patients with falciparum malaria, which is prognostic for progression to severe malaria and case fatality. Plasma PfHRP2 concentrations are typically quantified using enzyme-linked immunosorbent assay (ELISA) methods. We assessed whether band intensity on a PfHRP2-based ultrasensitive rapid diagnostic test (RDT) can provide a semi-quantitative measure for plasma PfHRP2 concentrations. Plasma samples from 60 African patients with severe falciparum malaria and 20 patients with uncomplicated falciparum malaria were assessed for PfHRP2 by ELISA and compared with RDT band intensity, assessed both visually and by digital scanning. Visual readings of RDT band intensity correlated with PfHRP2 plasma concentrations assessed by ELISA in patients with both uncomplicated (ρ = 0.80) and severe falciparum malaria (ρ = 0.61). Digitally assessed RDT band intensity in patients with severe malaria was higher than in patients with uncomplicated falciparum malaria. RDT band intensity correlates with plasma PfHRP2 concentration measured by ELISA and may offer a simple method for estimating total parasite burden in patients with falciparum malaria.

Chikungunya infection is caused by the Chikungunya alpha virus. The disease is characterized by an acute febrile illness that evolves to chronic, often severe, polyarticular limb arthralgia in approximately 30% of patients. There are no specific treatments for Chikungunya. To characterize the dynamics of viraemia in order to plan future antiviral studies, we took daily blood samples and evaluated serial viral densities measured by RT-PCR in a cohort of 19 adult Brazilian patients with acute Chikungunya infection. Viraemia exhibited a rapid decline, and most individuals were RT-PCR negative by day 4 after study entry. Higher viral loads were associated with earlier clinical presentations. Concentrations of sTNFR1 closely followed the decline in Chikungunya viral loads. Viral clearance measurements may be useful for the development and evaluation of novel treatments for Chikungunya infection. This article is part of the Theo Murphy meeting issue 'Evaluating anti-infective drugs'.

BackgroundMurine typhus, caused by Rickettsia typhi, is a treatable febrile illness in Laos, where azithromycin treatment failure has been reported. Antibiotic susceptibility testing for Rickettsia spp. is challenging due to absence of resistant strains. We aimed to induce an azithromycin-resistant in R. typhi and investigate its genetic basis.MethodologyR. typhi Wilmington was cultured in azithromycin-containing media (R. typhiAZM), starting at a concentration of 0.0019 mg/L and gradually increased to 0.0625 mg/L. Resistant populations were selected up to 0.125 mg/L. MICs were determined using plaque assay and qPCR, and DNA sequencing was performed for rplD (L4), rplV (L22), and 23S rRNA domain V. Protein modeling of azithromycin-binding sites was conducted, and strain stability was assessed over 24 passages without azithromycin (R. typhi AZM (-)).ResultsMICs for wild type (R. typhiWT) and R. typhiAZM were 2 mg/L versus >16 mg/L (plaque assay) and 0.25 mg/L versus 8 mg/L (qPCR). A 15-nucleotides insertion (5'-AAAGGAAGAGCAACT-3') was found in the rplV of R. typhiAZM, but not other isolates. Protein modeling suggested the insertion extends the L22 loop, potentially affecting azithromycin binding site within the ribosomal exit tunnel. R. typhiAZM reverted to wild type MIC and genotype by 24 passages without azithromycin. R. typhiAZM exhibited an 8 -fold higher MIC than R. typhiWT.ConclusionRepetitive insertion in rplV was associated with azithromycin resistance and may interfere with drug binding. R. typhiAZM was unstable without selective pressure. This approach may help generate resistant strains for assay validation. The role of rplV mutations in azithromycin susceptibility warrants further investigation.

Malaria, diarrhea and acute respiratory infections (ARIs) are the major causes of mortality in young children in sub-Saharan Africa. Here we provide support for the hypothesis that children can be protected from these diseases by improvements in house design. We designed a novel double-story house, called a Star Home, to provide an insect-proof, cleaner, cooler and smoke-free environment, with a reliable supply of water and sanitation. We conducted a cluster-randomized controlled trial where households with children under 13 years of age were randomly allocated (1:4.7) to living in 110 Star Homes or in 513 traditional mud and thatched-roofed houses. The primary outcome of childhood malaria incidence was met: after 3 years, children living in Star Homes had 44% less malaria (incidence rate ratio (IRR): 0.56 (95% confidence interval (CI): 0.43-0.72), P < 0.0001) compared to children living in traditional homes. Children in Star Homes had 30% less diarrhea (IRR: 0.70 (95% CI: 0.53-0.91), P = 0.0070) and 18% less ARIs (IRR: 0.82 (95% CI: 0.73-0.93), P = 0.0010) than children living in traditional homes. Children under 5 years of age living in Star Homes were also taller for their age than those living in traditional homes. Our house design is intended to inspire those working in the building sector and with local communities to develop innovative designs for healthier homes. Major improvements in rural house design have the potential to make a substantial public health impact across hot, humid regions of Africa. ClinicalTrials.gov: NCT04529434 .

Piperaquine resistance in Plasmodium falciparum has emerged in Southeast Asia and is strongly associated with mutations in the pfcrt gene and amplification of pfplasmepsin2/3. This study assessed the frequency of pfcrt mutations and pfplasmepsin2/3 gene amplifications across Southeast Asia over 25 years, which is critical for tracking resistant parasites. A total of 898 P. falciparum isolates collected from Thailand, Myanmar, Cambodia, Laos, and Vietnam between 1995 and 2023 were analyzed for pfcrt mutations, pfplasmepsin2 copy number, and microsatellite variation around the pfcrt locus. During the study period, pfcrt mutations in Cambodia across the study period showed that H97Y had the highest prevalence at 15%, followed by T93S at 8%, while I218F was common in 24% of specimens in Srisaket and Ubon in Thailand at 24.44%, followed by G353V at 20%, T93S at 17%, F145I at 13%, and H97Y at 4%. In Tak, Thailand, a mutation was found only in 1995 with 40% at I218F and the remaining wild-type. Yala in Thailand and Kayin State in Myanmar remained wild-type. Vietnam showed frequent T93S at 21%. The prevalence of pfcrt mutations observed in this study changed throughout the study period. Over 65% of parasites with pfcrt mutations at positions 93, 97, 145, 218, 343, and 353 also had pfplasmepsin2 amplification. Temporal analysis revealed that in Cambodia, pfplasmepsin2 CNV emerged first, peaking at 88% prevalence in 2015 after the introduction of DHA-piperaquine, with the subsequent increase of pfcrt mutations H97Y and G353V. In Eastern Thailand, both pfcrt mutations and pfplasmepsin2 CNV were highly prevalent, exceeding 70% during 2015-2018. In Vietnam, rapid increases in both markers were observed after 2012, reaching peak by 2017. Microsatellite analysis revealed reduced genetic diversity around mutant pfcrt alleles, indicating selective sweeps. This study demonstrates that frequencies of pfcrt mutations and pfplasmepsin2 amplification linked to piperaquine resistance have changed over time, highlighting the importance of ongoing genetic monitoring to inform strategies for preserving artemisinin-based combination therapy efficacy.

Historically malaria has been a major cause of morbidity and mortality in the Greater Mekong Sub-region. In recent years, significant progress towards malaria elimination has been made. Myanmar harbours most of the region’s malaria burden, however after initial progress during peace time, the civil war and the COVID-19 pandemic have coincided with a resurgence of malaria. This observational study examines the resurgence of malaria in Eastern Myanmar and its contributory factors. Malariometric and genomic data from a long-established network of malaria clinics and village health workers in eastern Karen State serving an estimated population of 350,000 were reviewed and analysed in the context of the COVID-19 pandemic and the military coup that followed. Data from 2020 and 2024 show that the number of cases of P. falciparum malaria increased 12-fold and those of P. vivax malaria increased threefold. This resurgence was greatest in the northern parts of Karen State and coincided with reduced access to timely diagnosis and treatment. This was associated with increased malaria transmission of P. falciparum (RR = 1.72, 95

Abstract Artemisinin resistance in Plasmodium falciparum is now well established in three continents and challenges the efficacy of antimalarial drug regimens. This study examined whether methylene blue, an ancient antimalarial drug with a broad spectrum of activity against Plasmodium blood stages, retains its activity against the young rings of artemisinin-resistant parasites. Clinical isolates carrying kelch13 wild type (n = 3), R561H (n = 9), or P441L (n = 10) genotypes were tested with a modified ring survival assay whereby 0- to 3-h post-invasion rings were exposed to a range of methylene blue concentrations. Ring survival was analysed with a Bayesian mixed effects Emax model accounting for variability across isolates and experimental replicates. Methylene blue suppressed ring-stage survival at low nanomolar concentrations with no evidence of kelch13-mediated cross-resistance: the mean 50% inhibitory concentration (IC50) estimates were 23 nM (95% credible interval [CrI]: 15 to 37) for wild type, 27 nM (95% CrI: 21 to 36) for R561H and 14 nM (95% CrI: 10 to 20) for P441L. These findings indicate that methylene blue remains active in vitro against ring-stage artemisinin-resistant parasites.

Pharmacometric assessment of antiviral efficacy in acute influenza informs treatment decisions and pandemic preparedness. We characterized natural viral clearance in acute influenza to guide phase II trial design using simulations based upon observed data. Standardized duplicate oropharyngeal swabs were collected daily over 14 days from 80 untreated low-risk Thai adults, with viral densities measured using quantitative polymerase chain reaction. We evaluated three models to describe viral clearance: exponential, bi-exponential and growth-and-decay. The growth-and-decay model provided the best fit, but the exponential decay model was the most parsimonious. The median viral clearance half-life was 10.3 h (interquartile range (IQR): 6.8-15.4h), varying by influenza type: 9.6 h (IQR: 6.2-13.0 h) for influenza A and 14.0 h (IQR: 10.3-19.3 h) for influenza B. Simulated trials using parameters from the exponential decay model showed that 148 patients per arm provide over 90% power to detect treatments accelerating viral clearance by 40%. Variation in clearance rates strongly impacted the power; doubling this variation would require 232 patients per arm for an antiviral with a 60% effect size. A sampling strategy with four swabs per day reduces the required sample size to 81 per arm while maintaining over 80% power. We recommend this approach to assess and compare current anti-influenza drugs. This article is part of the Theo Murphy meeting issue 'Evaluating anti-infective drugs'.

Background Cerebral malaria is a major cause of death in endemic areas. An animal model of cerebral malaria has been studied widely in which C57BL/6 mice are infected with the Plasmodium berghei ANKA strain. The histopathology and the response to interventions of human cerebral malaria and the murine model are very different. In 2012, a consensus guideline was published recommending that in order to represent better the clinical setting, interventions in the murine model should be tested together with antimalarial drug treatment and after development of the cerebral syndrome.Methods A systematic review of publications on human and murine cerebral malaria since 2010 was conducted.Results Clinical research on human cerebral malaria has declined and still no adjuvant intervention has proved effective. Meanwhile, since 2010, 149 interventions (118 adjuvants) have been evaluated in the mouse model, of which 142 (95%) were reportedly successful. Only 26% of interventions were evaluated after the development of the murine cerebral syndrome and 65% of the adjuvants were tested without a concomitant antimalarial.Conclusion The predictive value of the murine model in identifying adjuvant therapeutic interventions in human cerebral malaria is very poor.

INTRODUCTION:Malaria remains a major public health burden in Bangladesh, particularly in the Chittagong Hill Tracts (CHT), where indigenous and marginalized populations face persistent transmission risks. The Mass Vaccine and Drug Administration (MVDA) trial is currently being implemented to accelerate malaria elimination. MVDA is socially complex because it involves administering preventive interventions to largely asymptomatic populations in contexts where trust, prior experiences, and sociopolitical factors strongly shape acceptance. Little is known about community perspectives toward such interventions. This study explored local understandings of malaria, health-seeking behaviours, and perceptions of mass vaccine and drug administration in the CHT to inform community engagement and implementation of MVDA. METHODS:A qualitative study collected data using focus group discussions (FGDs), in-depth interviews (IDIs), and key informant interviews (KIIs) in Lama and Alikadam sub-districts of Bandarban among community members with no prior exposure to formal research activities. Participants were purposively selected using a maximum variation sampling approach to capture diverse perspectives across socio-demographic and stakeholder groups. Participants included community members, village leaders, traditional healers, local pharmacists, village health workers, religious leaders, and local government representatives. A total of 105 participants from heterogeneous backgrounds participated in this study between September and October 2024. Data were transcribed, translated, and underwent primarily inductive thematic analysis led by a trained qualitative researcher, a Bengali non-native to the study site. Interpretation was conducted reflexively, considering the researcher's positionality. RESULTS:Malaria was recognized as a recurrent illness, particularly during the rainy season and among traditional farmers. While awareness of malaria symptoms and prevention had increased through non-governmental and government initiatives, health-seeking behaviour remained pluralistic. Communities relied on traditional healers and informal drug sellers before seeking formal care. Village health workers provided malaria diagnosis and treatment but faced challenges of inconsistent services (e.g., irregular supply of health materials). The recent COVID-19 experience seemed to shape vaccine perceptions, with mandates, and adverse event narratives contributing to mistrust. Knowledge of a malaria vaccine was limited, yet participants expressed conditional acceptance, indicating willingness to participate if interventions were perceived as safe, effective, and transparently communicated. MDAs were viewed more positively than mass vaccine administration(s) although adherence, particularly among children and adults was considered a challenge. Trust in institutions and historical political mistrust emerged as key determinants shaping community attitudes toward MVDA. These findings informed the design of community engagement strategies accompanying the MVDA intervention. CONCLUSIONS:The success of MVDA depends on achieving high population coverage, which is contingent on trust, legitimacy, and effective community engagement. In socially and politically complex settings such as the CHT, implementation must be grounded in context-specific strategies that are responsive to local social and cultural dynamics and informed by community perspectives.

Pivotal clinical studies of new anti-infective drugs enrol patients with strictly defined clinical syndromes, with clinical and laboratory endpoints used to define treatment success. Assessing bacterial killing in the host by serial quantitation has potential as a more efficient pharmacometric approach to assess antibiotic efficacy. We conducted a systematic review of the use of bacterial quantitation in clinical infection. The main syndromes studied in the 222 included articles were bacteraemia, chronic respiratory disease, diarrhoea, pneumonia and sexually transmitted infections. Most reports (135 articles, 61%) quantified bacterial load in different specimen types using quantitative polymerase chain reaction (qPCR). For bacteraemias, bacterial DNA load measured in whole blood by qPCR at clinical presentation was typically 2-3 log10 copies ml-1, usually substantially higher than the estimates from quantitative culture. Higher bacterial loads were associated with increased mortality in 28 of 35 studies. Faster bacterial clearance was correlated with appropriate antibiotic therapy and improved outcome in the majority of studies. Most studies sampled too infrequently for accurate characterization of bacterial clearance rates. The rate of bacterial clearance from blood or other compartments is an informative pharmacodynamic endpoint in the assessment of antibacterial therapeutic effects, but standardized approaches to assessment are needed based on optimal study design. This article is part of the Theo Murphy meeting issue 'Evaluating anti-infective drugs'.

Ivermectin is used in the treatment of several neglected tropical diseases. Studies have shown that it effectively kills anopheline mosquitoes. However, the relationship between the pharmacokinetic properties and mosquito-lethal effects have not been described quantitatively. Pharmacokinetic properties and mosquito-lethal effects associated with a single oral administration of ivermectin were evaluated in two healthy volunteer trials in Thailand. All data were pooled and analysed using nonlinear mixed-effect modelling. Ivermectin and metabolites were described by a parent-metabolite model. When co-administered with dihydroartemisinin-piperaquine, a reduced elimination clearance (41%) and a slower absorption (32%) of ivermectin was identified, resulting in higher exposures. Different peripheral volume of distributions of ivermectin in men and women were also observed (75% higher in females). Individual pharmacokinetic profiles were incorporated in a sigmoidal Emax model, which were used to quantify the relationship between ivermectin exposure and mosquito-lethal effects. The integrated models described successfully the observed mortality of both Anopheles dirus and An. minimus. The final models were used to illustrate the potential impact on vector-control associated with ivermectin administration. In conclusion, ivermectin and its metabolites showed effective mosquito-lethal effects. The developed pharmacometric framework could be a useful tool in the evaluation of ivermectin as a potential vector-control agent in malaria elimination campaigns.

BACKGROUND:Malaria in pregnancy causes adverse effects on the mother and fetus, requiring effective antimalarial treatment. Understanding the transplacental transfer of antimalarials is vital to assessing fetal safety and the risk of congenital malaria. METHODS:We assessed a triad of blood samples (mother and neonatal capillary, cord) at delivery among women who were treated for uncomplicated malaria with artemether-lumefantrine (AL), artesunate-mefloquine (ASMQ), or dihydroartemisinin-piperaquine (DP) 4-8 weeks before delivery. RESULTS:Antimalarial drug concentrations at delivery were measured in 90 women (25 AL, 29 ASMQ, 36 DP). Drug concentrations were detectable in neonates at birth at a maximum of 27, 42, and 55 days after the first dose of lumefantrine, mefloquine, and piperaquine, respectively. The blood concentrations were highest in the mother, followed by the neonate, and lowest in cord blood. Piperaquine showed the highest neonate-to-mother (N/M) ratio (geometric mean, 0.98; 95% confidence interval, 0.67-1.44; n = 32) followed by carboxy-mefloquine (0.90; 0.75-1.08; n = 27), desbutyl-lumefantrine (0.44; 0.30-0.65; n = 16), mefloquine (0.42; 0.38-0.47; n = 26), and lumefantrine (0.31; 0.07-1.36; n = 9). Higher maternal body mass index was associated with a lower N/M ratio of desbutyl-lumefantrine. Female neonatal sex and a longer interval following drug administration were associated with higher N/M ratios of carboxy-mefloquine. No increased risk of jaundice was observed. CONCLUSIONS:Antimalarial drugs crossed the placenta variably. Neonatal concentrations ranged from less than half (lumefantrine, mefloquine) to near maternal equivalence (piperaquine). Collection of neonatal capillary samples at birth should be considered in future studies.SummaryWe compared antimalarial blood concentrations in mothers, neonates, and cords. Neonatal drug concentrations ranged from near maternal equivalence (piperaquine) to less than half (lumefantrine, mefloquine). Cord concentrations may underestimate neonatal exposure. Future studies should consider neonatal capillary sampling.

BACKGROUND:The oral antiviral therapies baloxavir marboxil (hereafter baloxavir), favipiravir, and oseltamivir have not been simultaneously compared for the treatment of seasonal influenza. We aimed to determine their relative efficacies in accelerating viral clearance in patients with symptomatic influenza virus infection at low risk of progression to severe disease. METHODS:We conducted a phase 2, open-label, randomised, controlled, adaptive platform trial in patients aged 18-60 years in Thailand, Laos, Nepal, and Brazil, recruited in four hospital outpatient or primary care departments with acute influenza (≤ 4 days of symptoms) and a low risk of progression to severe disease. Patients were randomly assigned 1:1:1:1:1 using a centralised online app to receive baloxavir (single oral dose of 40 mg if bodyweight <80 kg or 80 mg if bodyweight ≥80 kg), favipiravir (oral loading dose of 1800 mg, followed by 1800 mg 12 h later, and then 800 mg twice daily for 4 days), oseltamivir (oral dose 75 mg twice daily for 5 days), no study drug, or another ongoing intervention (reported separately). Randomisation was stratified by site and used block sizes of 15. The primary endpoint was the rate of oropharyngeal influenza viral RNA clearance, estimated under a Bayesian hierarchical linear model fitted to the daily log10 oropharyngeal viral densities from day 0 to day 5. Analyses were conducted in the modified intention-to-treat population (mITT), defined as patients with PCR-confirmed influenza with more than 250 viral RNA copies per mL at randomisation. Intervention groups were assessed for superiority over the no study drug group (posterior probability >0·9 that the relative increase in viral clearance was ≥20%); if superiority was met, intervention groups were assessed for non-inferiority relative to baloxavir (posterior probability >0·9 that the relative reduction in viral clearance was ≤10%). Secondary outcomes included time to resolution of fever and time to resolution of all symptoms. The trial is registered with ClinicalTrials.gov (NCT05648448) and is ongoing. FINDINGS:Between Feb 22, 2023, and Dec 12, 2025, 944 patients with influenza virus infection were randomly assigned to baloxavir (n=199; mITT 163 [82%]), favipiravir (n=223; mITT 196 [88%]), oseltamivir (n=200; mITT 170 [85%]), no study drug (n=228; mITT 200 [88%]) or other interventions (n=94). 120 patients were excluded based on baseline viral density (≤250 copies per mL), and one participant withdrew before collection of quantitative PCR results on day 0. 457 (63%) patients in the mITT population were female and 272 (37%) were male. Compared with no study drug, viral clearance rates were accelerated by 86% (95% credible interval [CrI] 60-117) with baloxavir, 66% (45-94) with favipiravir, and 49% (28-74) with oseltamivir. For all interventions, the posterior probability that the relative increase in viral clearance was 20% or more was 1·0. Compared with baloxavir, oseltamivir was inferior (20% slower clearance, 95% CrI 6 to 32; posterior probability 0·93 that the relative reduction in viral clearance was <10%); non-inferiority could not be shown for favipiravir (10% slower clearance, 95% CrI -4 to 22; posterior probability 0·55 that the relative reduction in viral clearance was <10%). Median time to fever resolution was accelerated with all three antivirals compared with no study drug (absolute differences ranging from 0·5 days to 0·9 days), whereas time to resolution of all symptoms was not significantly different between groups. 31 adverse events of grade 3 or above occurred, five of which were considered severe (one in the favipiravir group, one in the oseltamivir group, and three in the no study drug group). INTERPRETATION:Oral baloxavir, favipiravir, and oseltamivir accelerated influenza viral clearance rates in adults with early non-severe seasonal influenza at low risk of progression to severe disease. Baloxavir had the greatest in-vivo antiviral efficacy, followed by favipiravir and oseltamivir. These antivirals shortened fever duration but showed no clear effects on time to complete symptom resolution. This pharmacometric approach can inform prioritisation of antiviral agents for further study and potential inclusion in pandemic stockpiles. FUNDING:Wellcome Trust.

Despite the 2012 WHO recommendation to add single low dose primaquine (SLDPQ, 0.25 mg/kg body weight) to artemisinin-based combination treatments (ACTs) for blocking the transmission of artemisinin-resistant Plasmodium falciparum, there are currently no weight-based regimens founded on robust evidence. Applying published safety, transmission blocking and pharmacokinetic data, and exploring pharmacokinetic-pharmacodynamic relationships of age-based dosing of SLDPQ in African children with acute, uncomplicated Plasmodium falciparum, we derived weight-based, stand-alone, ACT-, triple ACT-, and vivax-matched regimens by following allometric dosing principles and simulating PQ exposure (area under the concentration time curve). The ACTs were dihydroartemisinin piperaquine (DHAPP), artesunate pyronaridine (ASPYR), artesunate amodiaquine (ASAQ), artesunate mefloquine (ASMQ), artemether lumefantrine (AL), and ALAQ. Tablet strengths were predefined: 2.5, 3.75, 5, 7.5, and 15 mg, and no tablet fractions were allowed. The maximum mg/kg dose was set at 0.5, and, primarily for ease of ACT co-blistering, 1 tablet = 1 dose. We assessed different mg/kg doses and selected the dosing associated with a predicted median exposure closest to 1200 ng*h/mL, the exposure predicted for a 60 kg individual given 15 mg of PQ. The designed 8 regimens had 4–8 dosing bands. The stand-alone, DHAPP, and ASPYR regimens contain the full line of PQ tablets and all other regimens, except AL (2.5, 7.5, 15 mg) and ALAQ (2.5, 5, 7.5, 15 mg), use 3.75 mg. The 2.5 mg tablet resulted in a maximum dose of 0.56 mg/kg for ASAQ, as this regimen starts at 4.5 kg body weight, whilst all other regimens start at 5 kg and resulted in 0.5 mg/kg. Substituting 3.75 mg with 5 mg results in maximum doses of 0.56 mg/kg (ASAQ, ASMQ) and 0.63 mg/kg (other regimens), risking greater toxicity. Across all dosing bands, 0.17 − 0.56 mg/kg doses predict exposures of 500 − 2000 ng*mL/h. Regimens with more dosing bands had less variations in exposure. These regimens offer flexibility for malaria control programmes and guidance for drug manufacturers wishing to co-blister SLDPQ with ACTs. The WHO should reinstate the 3.75 mg tablet for prequalification and determine which regimens should be incorporated into their treatment guidelines to advance malaria elimination. The trial is registered at ISRCTN, number 11594437.

Background: Ensitrelvir is an oral antiviral treatment for COVID-19 with the same molecular target as ritonavir-boosted nirmatrelvir - the current oral first-line treatment. There have been no direct comparisons between the two drugs. Methods: In an open label controlled adaptive pharmacometric platform trial, low-risk adult patients aged 18-60 years with early symptomatic COVID-19 (<4 days of symptoms) were randomised concurrently to one of eight treatment arms including ensitrelvir, ritonavir-boosted nirmatrelvir, and no study drug. The primary endpoint was the rate of oropharyngeal viral clearance assessed in a modified intention-to-treat population (mITT), defined as patients with >3 days of follow-up. Viral clearance rate was derived under a Bayesian hierarchical linear model fitted to the log10 viral densities in standardised duplicate oropharyngeal swab eluates taken daily over five days (14 measurements). This trial is registered at ClinicalTrials.gov ([NCT05041907][1]). Findings: Between March 2023 and April 2024 the three study arms randomised 604 patients concurrently in Thailand and Lao PDR (ensitrelvir 202; ritonavir-boosted nirmatrelvir 207; no study drug 195) among 903 patients enrolled. All patients recovered uneventfully. Ensitrelvir was very well tolerated and did not cause dysgeusia. Median (interquartile range) estimated SARS-CoV-2 clearance half-lives were 5.9 hours (4.0 to 8.6) with ensitrelvir; 5.2 hours (3.8 to 6.6) with nirmatrelvir; and 11.6 hours (8.1 to 14.5) with no study drug. Viral clearance following ensitrelvir was 82% (95% credible interval, CrI: 61 to 104%) faster than no study drug and 16% (95% CrI: 5 to 25%) slower than ritonavir-boosted nirmatrelvir. Viral rebound occurred in 15 (7%) of the nirmatrelvir group and 10 (5%) of the ensitrelvir group (p=0.4). Conclusions: Both ensitrelvir and nirmatrelvir markedly accelerate oropharyngeal SARS-CoV-2 viral clearance. Ensitrelvir is an efficacious and well tolerated alternative to currently available antivirals in treating COVID-19. Funding: Finding treatments for COVID-19: A phase 2 multi-centre adaptive platform trial to assess antiviral pharmacodynamics in early symptomatic COVID-19 (PLAT-COV) is supported by the Wellcome Trust Grant ref: 223195/Z/21/Z through the COVID-19 Therapeutics Accelerator. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT05041907 ### Funding Statement Finding treatments for COVID-19: A phase 2 multi-centre adaptive platform trial to assess antiviral pharmacodynamics in early symptomatic COVID-19 (PLAT-COV) is supported by the Wellcome Trust Grant ref: 223195/Z/21/Z through the COVID-19 Therapeutics Accelerator. ### 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: The trial was approved by local and national research ethics boards in Thailand (Faculty of Tropical Medicine Ethics Committee, Mahidol University FTMEC Ref: TMEC 21-058, approval number MUTM 2021-057-03) and the Central Research Ethics Committee (CREC, Bangkok, Thailand, CREC Ref: CREC048/64BP-MED34) in Laos by the National Ethics Committee for Health Research (NECHR Lao PDR, Submission ID 2022.48) and the Federal Drug Administration (FDA, Lao PDR, 13066/FDD_12Dec2022) and by the Oxford University Tropical Research Ethics Committee (OxTREC, Oxford, UK, OxTREC Ref: 24-21). 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 All data produced are available online at https://github.com/jwatowatson/PLATCOV-Ensitrelvir [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05041907&atom=%2Fmedrxiv%2Fearly%2F2025%2F05%2F21%2F2025.05.18.25327861.atom

Background:The selective serotonin reuptake inhibitors (SSRIs) fluoxetine and fluvoxamine were repurposed for the treatment of early COVID-19 based on their antiviral activity in vitro, and observational and clinical trial evidence suggesting they prevented progression to severe disease. However, these SSRIs have not been recommended in therapeutic guidelines and their antiviral activity in vivo has not been characterised. Methods:PLATCOV is an open-label, multicentre, phase 2, randomised, controlled, adaptive pharmacometric platform trial running in Thailand, Brazil, Pakistan, and Laos. We recruited low-risk adult outpatients aged 18-50 with early symptomatic COVID-19 (symptoms <4 days) between 5 April 2022 and 8 May 2023. Patients were assigned using block randomisation to one of eleven treatment arms including oral fluoxetine (40 mg/day for 7 days), or no study drug. Uniform randomisation ratios were applied across the active treatment groups while the no study drug group comprised ≥20% of patients at all times. The primary endpoint was the rate of oropharyngeal viral clearance assessed until day 7. Measurements were taken daily between days 0 and 7 and analysed in a modified intention-to-treat population (>2 days follow-up).The viral clearance rate was estimated under a Bayesian hierarchical linear model fitted to the log10 viral densities measured in standardised duplicate oropharyngeal swab eluates taken daily over one week (18 measurements per patient). Secondary endpoints were all-cause hospital admission at 28 days, and time to resolution of fever and symptoms. This ongoing trial is registered at ClinicalTrials.gov (NCT05041907). Findings:271 patients were concurrently randomised to either fluoxetine (n = 120) or no study drug (n = 151). All patients had received at least one COVID-19 vaccine dose and 67% were female (182/271). In the primary analysis, viral clearance rates following fluoxetine were compatible with a small or no increase relative to the no study drug arm (15% increase; 95% credible interval (CrI): -2 to 34%). There were no deaths or hospitalisations in either arm. There were no significant differences in times to symptom resolution or fever clearance between the fluoxetine and the no study drug arms (although only a quarter of patients were febrile at baseline). Fluoxetine was well tolerated, there were no serious adverse events and only one grade 3 adverse event in the intervention arm. Interpretation:Overall, the evidence from this study is compatible with fluoxetine having a weak in vivo antiviral activity against SARS-CoV-2, although the primary endpoint is also compatible with no effect. This level of antiviral efficacy is substantially less than with other currently available antiviral drugs. Funding:Wellcome Trust Grant ref: 223195/Z/21/Z through the COVID-19 Therapeutics Accelerator.