An unusual case of dengue fever in aneurysmal subarachnoid haemorrhage: diagnosis and management nuances

BACKGROUND

Dengue fever is highly prevalent in the Asia-Pacific region. Here we present an unusual case of dengue fever in a patient with a ruptured cerebral aneurysm causing subarachnoid (SAH) and intraventricular haemorrhage (IVH) and discuss the implications of dengue-related thrombopathies on the management of SAH and its complications.

CASE REPORT

A 56-year-old female with a two-day history of high-grade pyrexia and myalgia presented with sudden-onset drowsiness (presenting Glasgow Coma Scale, GCS: E1V1M4). Imaging revealed extensive SAH and IVH due to a ruptured right middle cerebral artery (MCA) aneurysm, with extensive vasospasm. Blood test revealed thrombocytopenia and a positive NS-1 antigen. She subsequently suffered from two episodes of re-rupture of the aneurysm and elevated intracranial pressure which required a decompressive craniectomy in addition to coilingof the MCA aneurysm. Cerebral perfusion and rheology were maintained with the triple-H therapy. Her GCS improved to E4V1M6, but remained aphasic.

DISCUSSIONS

Thrombocytopenia and deranged platelet functions in dengue infection might affect the stability of clot and increase the risk of re-rupture of aneurysm. Immediate securement of the aneurysm was paramount. In cases of severe dengue, plasma leakage could lead to intravascular depletion, and coupled with haemoconcentration and hypotension would further increase the risk for vasospasm.

Minding the "T"s beyond the "B"s: Shaping vaccines for future pandemics

The COVID-19 pandemic has accelerated the development of vaccines for viral infections. However, a failure to integrate T cell immunity as a determinant of vaccine efficacy could curtail advancement of newer vaccines for pandemic preparedness.

Early oral antibiotic switch in Staphylococcus aureus bacteraemia: The Staphylococcus aureus Network Adaptive Platform (SNAP) Trial Early Oral Switch Protocol

BACKGROUND

Staphylococcus aureus bloodstream infection (bacteraemia) is traditionally treated with at least two weeks of IV antibiotics in adults, 3-7 days in children, and often longer for those with complicated disease. The current practice of treating S. aureus bacteraemia (SAB) with prolonged IV antibiotics (rather than oral antibiotics) is based on historical observational research and expert opinion. Prolonged IV antibiotic therapy has significant disadvantages for patients and healthcare systems, and there is growing interest in whether a switch to oral antibiotics following an initial period of IV therapy is a safe alternative for clinically stable patients.

PROTOCOL

The early oral switch (EOS) domain of the S. aureus Network Adaptive Platform (SNAP) trial will assess early switch to oral antibiotics compared with continued IV treatment in clinically stable patients with SAB. The primary endpoint is 90-day all-cause mortality. Hospitalised SAB patients are assessed at platform day 7 +/- 2 (uncomplicated SAB) and day 14 +/-2 (complicated SAB) to determine their eligibility for randomisation to EOS (intervention) or continued IV treatment (current standard of care).

DISCUSSION

Recruitment is occurring to the EOS domain of the SNAP trial. As of August 2023, 21% of all SNAP participants had been randomised to the EOS domain, a total of 264 participants across 77 centres, with an aim to recruit at least 1000 participants. We describe challenges and facilitators to enrolment in this domain to aid those planning similar trials.

Mast cell activation in lungs during SARS-CoV-2 infection associated with lung pathology and severe COVID-19

Lung inflammation is a hallmark of Coronavirus disease 2019 (COVID-19) in patients who are severely ill, and the pathophysiology of disease is thought to be immune mediated. Mast cells (MCs) are polyfunctional immune cells present in the airways, where they respond to certain viruses and allergens and often promote inflammation. We observed widespread degranulation of MCs during acute and unresolved airway inflammation in SARS-CoV-2-infected mice and nonhuman primates. Using a mouse model of MC deficiency, MC-dependent interstitial pneumonitis, hemorrhaging, and edema in the lung were observed during SARS-CoV-2 infection. In humans, transcriptional changes in patients requiring oxygen supplementation also implicated cells with a MC phenotype in severe disease. MC activation in humans was confirmed through detection of MC-specific proteases, including chymase, the levels of which were significantly correlated with disease severity and with biomarkers of vascular dysregulation. These results support the involvement of MCs in lung tissue damage during SARS-CoV-2 infection in animal models and the association of MC activation with severe COVID-19 in humans, suggesting potential strategies for intervention.

Acquisition of regulator on virulence plasmid of hypervirulent Klebsiella allows bacterial lifestyle switch in response to iron

Hypervirulent Klebsiella pneumoniae causes liver abscess and potentially devastating metastatic complications. The majority of Klebsiella-induced liver abscess are caused by the CG23-I sublineage of hypervirulent Klebsiella pneumoniae. This and some other lineages possess a >200-kb virulence plasmid. We discovered a novel protein IroP nestled in the virulence plasmid-encoded salmochelin operon that cross-regulates and suppresses the promoter activity of chromosomal type 3 fimbriae (T3F) gene transcription. IroP is itself repressed by iron through the ferric uptake regulator. Iron-rich conditions increase T3F and suppress capsule mucoviscosity, leading to biofilm formation and cell adhesion. Conversely, iron-poor conditions cause a transcriptional switch to hypermucoid capsule production and T3F repression. The likely acquisition of iroP on mobile genetic elements and successful adaptive integration into the genetic circuitry of a major lineage of hypervirulent K. pneumoniae reveal a powerful example of plasmid chromosomal cross talk that confers an evolutionary advantage. Our discovery also addresses the conundrum of how the hypermucoid capsule that impedes adhesion could be regulated to facilitate biofilm formation and colonization. The acquired ability of the bacteria to alternate between a state favoring dissemination and one that favors colonization in response to iron availability through transcriptional regulation offers novel insights into the evolutionary success of this pathogen. IMPORTANCE Hypervirulent Klebsiella pneumoniae contributes to the majority of monomicrobial-induced liver abscess infections that can lead to several other metastatic complications. The large virulence plasmid is highly stable in major lineages, suggesting that it provides survival benefits. We discovered a protein IroP encoded on the virulence plasmid that suppresses expression of the type 3 fimbriae. IroP itself is regulated by iron, and we showed that iron regulates hypermucoid capsule production while inversely regulating type 3 fimbriae expression through IroP. The acquisition and integration of this inverse transcriptional switch between fimbriae and capsule mucoviscosity shows an evolved sophisticated plasmid-chromosomal cross talk that changes the behavior of hypervirulent K. pneumoniae in response to a key nutrient that could contribute to the evolutionary success of this pathogen.

Insights into dengue immunity from vaccine trials

The quest for an effective dengue vaccine has culminated in two approved vaccines and another that has completed phase 3 clinical trials. However, shortcomings exist in each, suggesting that the knowledge on dengue immunity used to develop these vaccines was incomplete. Vaccine trial findings could refine our understanding of dengue immunity, because these are experimentally derived, placebo-controlled data. Results from these trials suggest that neutralizing antibody titers alone are insufficient to inform protection against symptomatic infection, implicating a role for cellular immunity in protection. These findings have relevance for both future dengue vaccine development and application of current vaccines for maximal public health benefit.

Longer-term Mortality and Kidney Outcomes of Participants in the Combination Antibiotics for Methicillin-Resistant Staphylococcus aureus (CAMERA2) Trial: A Post Hoc Analysis

Background

The Combination Antibiotic Therapy for Methicillin-Resistant Staphylococcus aureus (CAMERA2) trial ceased recruitment in July 2018, noting that a higher proportion of patients in the intervention arm (combination therapy) developed acute kidney injury (AKI) compared to the standard therapy (monotherapy) arm. We analyzed the long-term outcomes of participants in CAMERA2 to understand the impact of combination antibiotic therapy and AKI.

Methods

Trial sites obtained additional follow-up data. The primary outcome was all-cause mortality, censored at death or the date of last known follow-up. Secondary outcomes included kidney failure or a reduction in kidney function (a 40% reduction in estimated glomerular filtration rate to <60 mL/minute/1.73 m²). To determine independent predictors of mortality in this cohort, adjusted hazard ratios were calculated using a Cox proportional hazards regression model.

Results

This post hoc analysis included extended follow-up data for 260 patients. Overall, 123 of 260 (47%) of participants died, with a median population survival estimate of 3.4 years (235 deaths per 1000 person-years). Fifty-five patients died within 90 days after CAMERA2 trial randomization; another 68 deaths occurred after day 90. Using univariable Cox proportional hazards regression, mortality was not associated with either the assigned treatment arm in CAMERA2 (hazard ratio [HR], 0.84 [95% confidence interval [CI], .59-1.19]; P = .33) or experiencing an AKI (HR at 1 year, 1.04 [95% CI, .64-1.68]; P = .88).

Conclusions

In this cohort of patients hospitalized with methicillin-resistant S aureus bacteremia, we found no association between either treatment arm of the CAMERA2 trial or AKI (using CAMERA2 trial definition) and longer-term mortality.

Cost-minimization analysis of oral versus intravenous antibiotic treatment for Klebsiella pneumoniae liver abscess

A cost-minimization analysis was conducted for Klebsiella pneumoniae liver abscess (KLA) patients enrolled in a randomized controlled trial which found oral ciprofloxacin to be non-inferior to intravenous (IV) ceftriaxone in terms of clinical outcomes. Healthcare service utilization and cost data were obtained from medical records and estimated from self-reported patient surveys in a non-inferiority trial of oral ciprofloxacin versus IV ceftriaxone administered to 152 hospitalized adults with KLA in Singapore between November 2013 and October 2017. Total costs were evaluated by category and payer, and compared between oral and IV antibiotic groups over the trial period of 12 weeks. Among the subset of 139 patients for whom cost data were collected, average total cost over 12 weeks was $16,378 (95% CI, $14,620-$18,136) for the oral ciprofloxacin group and $20,569 (95% CI, $18,296-$22,842) for the IV ceftriaxone group, largely driven by lower average outpatient costs, as the average number of outpatient visits was halved for the oral ciprofloxacin group. There were no other statistically significant differences, either in inpatient costs or in other informal healthcare costs. Oral ciprofloxacin is less costly than IV ceftriaxone in the treatment of Klebsiella liver abscess, largely driven by reduced outpatient service costs.Trial registration: ClinicalTrials.gov Identifier NCT01723150 (7/11/2012).

An experimental medicine decipher of a minimum correlate of cellular immunity: Study protocol for a double-blind randomized controlled trial

Vaccination induces an adaptive immune response that protects against infectious diseases. A defined magnitude of adaptive immune response that correlates with protection from the disease of interest, or correlates of protection (CoP), is useful for guiding vaccine development. Despite mounting evidence for the protective role of cellular immunity against viral diseases, studies on CoP have almost exclusively focused on humoral immune responses. Moreover, although studies have measured cellular immunity following vaccination, no study has defined if a “threshold” of T cells, both in frequency and functionality, is needed to reduce infection burden. We will thus conduct a double-blind, randomized clinical trial in 56 healthy adult volunteers, using the licensed live-attenuated yellow fever (YF17D) and chimeric Japanese encephalitis-YF17D (JE-YF17D) vaccines. These vaccines share the entire non-structural and capsid proteome where the majority of the T cell epitopes reside. The neutralizing antibody epitopes, in contrast, are found on the structural proteins which are not shared between the two vaccines and are thus distinct from one another. Study participants will receive JE-YF17D vaccination followed by YF17D challenge, or YF17D vaccination followed by JE-YF17D challenge. A separate cohort of 14 healthy adults will receive the inactivated Japanese Encephalitis virus (JEV) vaccine followed by YF17D challenge that controls for the effect of cross-reactive flaviviral antibodies. We hypothesize that a strong T cell response induced by YF17D vaccination will reduce JE-YF17D RNAemia upon challenge, as compared to JE-YF17D vaccination followed by YF17D challenge. The expected gradient of YF17D-specific T cell abundance and functionality would also allow us to gain insight into a T cell threshold for controlling acute viral infections. The knowledge gleaned from this study could guide the assessment of cellular immunity and vaccine development.

Clinical trial registration

Clinicaltrials.gov, NCT05568953.

Early peripheral blood MCEMP1 and HLA-DRA expression predicts COVID-19 prognosis

BACKGROUND

Mass vaccination has dramatically reduced the incidence of severe COVID-19, with most cases now presenting as self-limiting upper respiratory tract infections. However, those with co-morbidities, the elderly and immunocompromised, as well as the unvaccinated, remain disproportionately vulnerable to severe COVID-19 and its sequelae. Furthermore, as the effectiveness of vaccination wanes with time, immune escape SARS-CoV-2 variants could emerge to cause severe COVID-19. Reliable prognostic biomarkers for severe disease could be used as early indicator of re-emergence of severe COVID-19 as well as for triaging of patients for antiviral therapy.

METHODS

We performed a systematic review and re-analysis of 7 publicly available datasets, analysing a total of 140 severe and 181 mild COVID-19 patients, to determine the most consistent differentially regulated genes in peripheral blood of severe COVID-19 patients. In addition, we included an independent cohort where blood transcriptomics of COVID-19 patients were prospectively and longitudinally monitored previously, to track the time in which these gene expression changes occur before nadir of respiratory function. Single cell RNA-sequencing of peripheral blood mononuclear cells from publicly available datasets was then used to determine the immune cell subsets involved.

FINDINGS

The most consistent differentially regulated genes in peripheral blood of severe COVID-19 patients were MCEMP1, HLA-DRA and ETS1 across the 7 transcriptomics datasets. Moreover, we found significantly heightened MCEMP1 and reduced HLA-DRA expression as early as four days before the nadir of respiratory function, and the differential expression of MCEMP1 and HLA-DRA occurred predominantly in CD14+ cells. The online platform which we developed is publicly available at https://kuanrongchan-covid19-severity-app-t7l38g.streamlitapp.com/, for users to query gene expression differences between severe and mild COVID-19 patients in these datasets.

INTERPRETATION

Elevated MCEMP1 and reduced HLA-DRA gene expression in CD14+ cells during the early phase of disease are prognostic of severe COVID-19.

FUNDING

K.R.C is funded by the National Medical Research Council (NMRC) of Singapore under the Open Fund Individual Research Grant (MOH-000610). E.E.O. is funded by the NMRC Senior Clinician-Scientist Award (MOH-000135-00). J.G.H.L. is funded by the NMRC under the Clinician-Scientist Award (NMRC/CSAINV/013/2016-01). S.K. is funded by the NMRC under the Transition Award. This study was sponsored in part by a generous gift from The Hour Glass.

Immune gene expression analysis indicates the potential of a self-amplifying Covid-19 mRNA vaccine

Remarkable potency has been demonstrated for mRNA vaccines in reducing the global burden of the ongoing COVID-19 pandemic. An alternative form of the mRNA vaccine is the self-amplifying mRNA (sa-mRNA) vaccine, which encodes an alphavirus replicase that self-amplifies the full-length mRNA and SARS-CoV-2 spike (S) transgene. However, early-phase clinical trials of sa-mRNA COVID-19 vaccine candidates have questioned the potential of this platform to develop potent vaccines. We examined the immune gene response to a candidate sa-mRNA vaccine against COVID-19, ARCT-021, and compared our findings to the host response to other forms of vaccines. In blood samples from healthy volunteers that participated in a phase I/II clinical trial, greater induction of transcripts involved in Toll-like receptor (TLR) signalling, antigen presentation and complement activation at 1 day post-vaccination was associated with higher anti-S antibody titers. Conversely, transcripts involved in T-cell maturation at day 7 post-vaccination informed the magnitude of eventual S-specific T-cell responses. The transcriptomic signature for ARCT-021 vaccination strongly correlated with live viral vector vaccines, adjuvanted vaccines and BNT162b2 1 day post-vaccination. Moreover, the ARCT-021 signature correlated with day 7 YF17D live-attenuated vaccine transcriptomic responses. Altogether, our findings show that sa-mRNA vaccination induces innate immune responses that are associated with the development of adaptive immunity from other forms of vaccines, supporting further development of this vaccine platform for clinical application.

Conserved longitudinal alterations of anti-S-protein IgG subclasses in disease progression in initial ancestral Wuhan and vaccine breakthrough Delta infections

INTRODUCTION

COVID-19 has a wide disease spectrum ranging from asymptomatic to severe. While humoral immune responses are critical in preventing infection, the immune mechanisms leading to severe disease, and the identification of biomarkers of disease progression and/or resolution of the infection remains to be determined.

METHODS

Plasma samples were obtained from infections during the initial wave of ancestral wildtype SARS-CoV-2 and from vaccine breakthrough infections during the wave of Delta variant, up to six months post infection. The spike-specific antibody profiles were compared across different severity groups and timepoints.

RESULTS

We found an association between spike-specific IgM, IgA and IgG and disease severity in unvaccinated infected individuals. In addition to strong IgG1 and IgG3 response, patients with severe disease develop a robust IgG2 and IgG4 response. A comparison of the ratio of IgG1 and IgG3 to IgG2 and IgG4 showed that disease progression is associated with a smaller ratio in both the initial wave of WT and the vaccine breakthrough Delta infections. Time-course analysis revealed that smaller (IgG1 and IgG3)/(IgG2 and IgG4) ratio is associated with disease progression, while the reverse associates with clinical recovery.

DISCUSSION

While each IgG subclass is associated with disease severity, the balance within the four IgG subclasses may affect disease outcome. Acute disease progression or infection resolution is associated with a specific immunological phenotype that is conserved in both the initial wave of WT and the vaccine breakthrough Delta infections.

Case report: Understanding the impact of persistent tissue-localization of SARS-CoV-2 on immune response activity via spatial transcriptomic analysis of two cancer patients with COVID-19 co-morbidity

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected half a billion people, including vulnerable populations such as cancer patients. While increasing evidence supports the persistence of SARS-CoV-2 months after a negative nasopharyngeal swab test, the effects on long-term immune memory and cancer treatment are unclear. In this report, we examined post-COVID-19 tissue-localized immune responses in a hepatocellular carcinoma (HCC) patient and a colorectal cancer (CRC) patient. Using spatial whole-transcriptomic analysis, we demonstrated spatial profiles consistent with a lymphocyte-associated SARS-CoV-2 response (based on two public COVID-19 gene sets) in the tumors and adjacent normal tissues, despite intra-tumor heterogeneity. The use of RNAscope and multiplex immunohistochemistry revealed that the spatial localization of B cells was significantly associated with lymphocyte-associated SARS-CoV-2 responses within the spatial transcriptomic (ST) niches showing the highest levels of virus. Furthermore, single-cell RNA sequencing data obtained from previous (CRC) or new (HCC) ex vivo stimulation experiments showed that patient-specific SARS-CoV-2 memory B cells were the main contributors to this positive association. Finally, we evaluated the spatial associations between SARS-CoV-2-induced immunological effects and immunotherapy-related anti-tumor immune responses. Immuno-predictive scores (IMPRES) revealed consistent positive spatial correlations between T cells/cytotoxic lymphocytes and the predicted immune checkpoint blockade (ICB) response, particularly in the HCC tissues. However, the positive spatial correlation between B cells and IMPRES score was restricted to the high-virus ST niche. In addition, tumor immune dysfunction and exclusion (TIDE) analysis revealed marked T cell dysfunction and inflammation, alongside low T cell exclusion and M2 tumor-associated macrophage infiltration. Our results provide in situ evidence of SARS-CoV-2-generated persistent immunological memory, which could not only provide tissue protection against reinfection but may also modulate the tumor microenvironment, favoring ICB responsiveness. As the number of cancer patients with COVID-19 comorbidity continues to rise, improved understanding of the long-term immune response induced by SARS-CoV-2 and its impact on cancer treatment is much needed.

Chronic sequelae complicate convalescence from both dengue and acute viral respiratory illness

Long Covid has raised awareness of the potentially disabling chronic sequelae that afflicts patients after acute viral infection. Similar syndromes of post-infectious sequelae have also been observed after other viral infections such as dengue, but their true prevalence and functional impact remain poorly defined. We prospectively enrolled 209 patients with acute dengue (n = 48; one with severe dengue) and other acute viral respiratory infections (ARI) (n = 161), and followed them up for chronic sequelae up to one year post-enrolment, prior to the onset of the Covid-19 pandemic. Baseline demographics and co-morbidities were balanced between both groups except for gender, with more males in the dengue cohort (63% vs 29%, p<0.001). Except for the first visit, data on symptoms were collected remotely using a purpose-built mobile phone application. Mental health outcomes were evaluated using the validated SF-12v2 Health Survey. Almost all patients (95.8% of dengue and 94.4% of ARI patients) experienced at least one symptom of fatigue, somnolence, headache, concentration impairment or memory impairment within the first week of enrolment. Amongst patients with at least 3-months of follow-up, 18.0% in the dengue cohort and 14.6% in the ARI cohort experienced persistent symptoms. The median month-3 SF-12v2 Mental Component Summary Score was lower in patients who remained symptomatic at 3 months and beyond, compared to those whose symptoms fully resolved (47.7 vs. 56.0, p<0.001), indicating that patients who self-reported persistence of symptoms also experienced functionally worse mental health. No statistically significant difference in age, gender distribution or hospitalisation status was observed between those with and without chronic sequelae. Our findings reveal an under-appreciated burden of post-infection chronic sequelae in dengue and ARI patients. They call for studies to define the pathophysiology of this condition, and determine the efficacy of both vaccines as well as antiviral drugs in preventing such sequelae.

Chronic sequelae after viral infections such dengue have been observed, but their true prevalence and impact remain undefined. We prospectively enrolled a cohort of 209 patients with dengue and acute viral respiratory infections (ARI) and followed them up chronic sequelae for up to one year. 18% of patients in the dengue cohort and 14.6% of patients in the ARI cohort experienced chronic sequelae such as fatigue, somnolence, headache, concentration impairment and memory impairment. Patients who experienced chronic sequelae also had lower month-3 SF-12v2 Mental Component Summary Scores, suggesting that such those who self-reported persistence of symptoms experienced functionally worse mental health. Overall our findings reveal an under-appreciated burden of chronic sequelae in dengue and ARI patients and call for further studies to define the pathophysiology and potential therapeutic options for this condition.

Preclinical evaluation of [18F]FDG-PET as a biomarker of lymphoid tissue disease and inflammation in Zika virus infection

Purpose

Zika (ZIKV) is a viral inflammatory disease affecting adults, children, and developing fetuses. It is endemic to tropical and sub-tropical countries, resulting in half the global population at risk of infection. Despite this, there are no approved therapies or vaccines against ZIKV disease. Non-invasive imaging biomarkers are potentially valuable tools for studying viral pathogenesis, prognosticating host response to disease, and evaluating in vivo efficacy of experimental therapeutic interventions. In this study, we evaluated [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG)-positron emission tomography (PET) as an imaging biomarker of ZIKV disease in a mouse model and correlated metabolic tracer tissue uptake with real-time biochemical, virological, and inflammatory features of tissue infection.

Methods

[¹⁸F]FDG-PET/CT imaging was performed in an acute, lethal ZIKV mouse infection model, at increasing stages of disease severity. [¹⁸F]FDG-PET findings were corroborated with ex vivo wholemount-tissue autoradiography and tracer biodistribution studies. Tracer uptake was also correlated with in situ tissue disease status, including viral burden and inflammatory response. Immune profiling of the spleen by flow cytometry was performed to identify the immune cell subsets driving tissue pathology and enhancing tracer uptake in ZIKV disease.

Results

Foci of increased [¹⁸F]FDG uptake were consistently detected in lymphoid tissues—particularly the spleen—of ZIKV-infected animals. Splenic uptake increased with disease severity, and corroborated findings in tissue pathology. Increased splenic uptake also correlated with increased viral replication and elevated expression of pro-inflammatory cytokines within these tissues. ZIKV-infected spleens were characterized by increased infiltration of myeloid cells, as well as increased proliferation of both myeloid and lymphoid cells. The increased cell proliferation correlated with increased tracer uptake in the spleen. Our findings support the use of [¹⁸F]FDG as an imaging biomarker to detect and track ZIKV disease in real time and highlight the dependency of affected tissue on the nature of the viral infection.

Conclusion

[¹⁸F]FDG uptake in the spleen is a useful surrogate for interrogating in situ tissue viral burden and inflammation status in this ZIKV murine model.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05892-9.

Early oral stepdown antibiotic therapy versus continuing intravenous therapy for uncomplicated Gram-negative bacteraemia (the INVEST trial): study protocol for a multicentre, randomised controlled, open-label, phase III, non-inferiority trial

Background

The incidence of Gram-negative bacteraemia is rising globally and remains a major cause of morbidity and mortality. The majority of patients with Gram-negative bacteraemia initially receive intravenous (IV) antibiotic therapy. However, it remains unclear whether patients can step down to oral antibiotics after appropriate clinical response has been observed without compromising outcomes. Compared with IV therapy, oral therapy eliminates the risk of catheter-associated adverse events, enhances patient quality of life and reduces healthcare costs. As current management of Gram-negative bacteraemia entails a duration of IV therapy with limited evidence to guide oral conversion, we aim to evaluate the clinical efficacy and economic impact of early stepdown to oral antibiotics.

Methods

This is an international, multicentre, randomised controlled, open-label, phase III, non-inferiority trial. To be eligible, adult participants must be clinically stable / non-critically ill inpatients with uncomplicated Gram-negative bacteraemia. Randomisation to the intervention or standard arms will be performed with 1:1 allocation ratio. Participants randomised to the intervention arm (within 72 h from index blood culture collection) will be immediately switched to an oral fluoroquinolone or trimethoprim-sulfamethoxazole. Participants randomised to the standard arm will continue to receive IV therapy for at least 24 h post-randomisation before clinical re-assessment and decision-making by the treating doctor. The recommended treatment duration is 7 days of active antibiotics (including empiric therapy), although treatment regimen may be longer than 7 days if clinically indicated. Primary outcome is 30-day all-cause mortality, and the key secondary outcome is health economic evaluation, including estimation of total healthcare cost as well as assessment of patient quality of life and number of quality-adjusted life years saved. Assuming a 30-day mortality of 8% in the standard and intervention arms, with 6% non-inferiority margin, the target sample size is 720 participants which provides 80% power with a one-sided 0.025 α-level after adjustment for 5% drop-out.

Discussion

A finding of non-inferiority in efficacy of oral fluoroquinolones or trimethoprim-sulfamethoxazole versus IV standard of care antibiotics may hypothetically translate to wider adoption of a more cost-effective treatment strategy with better quality of life outcomes.

Trial registration

ClinicalTrials.govNCT05199324. Registered 20 January 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06495-3.

Adverse effects following anti–COVID-19 vaccination with mRNA-based BNT162b2 are alleviated by altering the route of administration and correlate with baseline enrichment of T and NK cell genes

Ensuring high vaccination and even booster vaccination coverage is critical in preventing severe Coronavirus Disease 2019 (COVID-19). Among the various COVID-19 vaccines currently in use, the mRNA vaccines have shown remarkable effectiveness. However, systemic adverse events (AEs), such as postvaccination fatigue, are prevalent following mRNA vaccination, and the underpinnings of which are not understood. Herein, we found that higher baseline expression of genes related to T and NK cell exhaustion and suppression were positively correlated with the development of moderately severe fatigue after Pfizer-BioNTech BNT162b2 vaccination; increased expression of genes associated with T and NK cell exhaustion and suppression reacted to vaccination were associated with greater levels of innate immune activation at 1 day postvaccination. We further found, in a mouse model, that altering the route of vaccination from intramuscular (i.m.) to subcutaneous (s.c.) could lessen the pro-inflammatory response and correspondingly the extent of systemic AEs; the humoral immune response to BNT162b2 vaccination was not compromised. Instead, it is possible that the s.c. route could improve cytotoxic CD8 T-cell responses to BNT162b2 vaccination. Our findings thus provide a glimpse of the molecular basis of postvaccination fatigue from mRNA vaccination and suggest a readily translatable solution to minimize systemic AEs.

Systemic adverse events, such as post-vaccination fatigue, are prevalent consequences of mRNA vaccination; why is this? This study shows that higher baseline expression of T and NK cell genes increases susceptibility to fatigue after mRNA vaccination, and that altering the route of vaccination may reduce the incidence of mRNA vaccine-associated systemic adverse events.

Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multicentre cohort study

OBJECTIVES

Highly effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed but variants of concerns are worrisome, especially B.1.617.2 (Delta) which has rapidly spread across the world. We aim to study if vaccination alters virological and serological kinetics in breakthrough infections.

METHODS

We conducted a multicentre retrospective cohort study of patients in Singapore who had received a licensed mRNA vaccine and been admitted to hospital with B.1.617.2 SARS-CoV-2 infection. We compared clinical features, virological and serological kinetics (anti-nucleocapsid, anti-spike and surrogate virus neutralization titres) between fully vaccinated and unvaccinated individuals.

RESULTS

Out of 218 individuals with B.1.617.2 infection, 84 received an mRNA vaccine of which 71 were fully vaccinated, 130 were unvaccinated and four received a non-mRNA vaccine. Despite significantly older age in the vaccine breakthrough group, only 2.8% (2/71) developed severe COVID-19 requiring oxygen supplementation compared with 53.1% (69/130) in the unvaccinated group (p < 0.001). Odds of severe COVID-19 following vaccination were significantly lower (adjusted odds ratio 0.07 95% CI 0.015-0.335, p 0.001). PCR cycle threshold values were similar between vaccinated and unvaccinated groups at diagnosis, but viral loads decreased faster in vaccinated individuals. Early, robust boosting of anti-spike protein antibodies was observed in vaccinated patients; however, these titres were significantly lower against B.1.617.2 than the wildtype vaccine strain.

DISCUSSION

The mRNA vaccines are highly effective at preventing symptomatic and severe COVID-19 associated with B.1.617.2 infection. Vaccination is associated with faster decline in viral RNA load and a robust serological response. Vaccination remains a key strategy for control of the COVID-19 pandemic.

Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multicentre cohort study

OBJECTIVES

Highly effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed but variants of concerns are worrisome, especially B.1.617.2 (Delta) which has rapidly spread across the world. We aim to study if vaccination alters virological and serological kinetics in breakthrough infections.

METHODS

We conducted a multicentre retrospective cohort study of patients in Singapore who had received a licensed mRNA vaccine and been admitted to hospital with B.1.617.2 SARS-CoV-2 infection. We compared clinical features, virological and serological kinetics (anti-nucleocapsid, anti-spike and surrogate virus neutralization titres) between fully vaccinated and unvaccinated individuals.

RESULTS

Out of 218 individuals with B.1.617.2 infection, 84 received an mRNA vaccine of which 71 were fully vaccinated, 130 were unvaccinated and four received a non-mRNA vaccine. Despite significantly older age in the vaccine breakthrough group, only 2.8% (2/71) developed severe COVID-19 requiring oxygen supplementation compared with 53.1% (69/130) in the unvaccinated group (p < 0.001). Odds of severe COVID-19 following vaccination were significantly lower (adjusted odds ratio 0.07 95% CI 0.015-0.335, p 0.001). PCR cycle threshold values were similar between vaccinated and unvaccinated groups at diagnosis, but viral loads decreased faster in vaccinated individuals. Early, robust boosting of anti-spike protein antibodies was observed in vaccinated patients; however, these titres were significantly lower against B.1.617.2 than the wildtype vaccine strain.

DISCUSSION

The mRNA vaccines are highly effective at preventing symptomatic and severe COVID-19 associated with B.1.617.2 infection. Vaccination is associated with faster decline in viral RNA load and a robust serological response. Vaccination remains a key strategy for control of the COVID-19 pandemic.

Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multicentre cohort study

OBJECTIVES

Highly effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed but variants of concerns are worrisome, especially B.1.617.2 (Delta) which has rapidly spread across the world. We aim to study if vaccination alters virological and serological kinetics in breakthrough infections.

METHODS

We conducted a multicentre retrospective cohort study of patients in Singapore who had received a licensed mRNA vaccine and been admitted to hospital with B.1.617.2 SARS-CoV-2 infection. We compared clinical features, virological and serological kinetics (anti-nucleocapsid, anti-spike and surrogate virus neutralization titres) between fully vaccinated and unvaccinated individuals.

RESULTS

Out of 218 individuals with B.1.617.2 infection, 84 received an mRNA vaccine of which 71 were fully vaccinated, 130 were unvaccinated and four received a non-mRNA vaccine. Despite significantly older age in the vaccine breakthrough group, only 2.8% (2/71) developed severe COVID-19 requiring oxygen supplementation compared with 53.1% (69/130) in the unvaccinated group (p < 0.001). Odds of severe COVID-19 following vaccination were significantly lower (adjusted odds ratio 0.07 95% CI 0.015-0.335, p 0.001). PCR cycle threshold values were similar between vaccinated and unvaccinated groups at diagnosis, but viral loads decreased faster in vaccinated individuals. Early, robust boosting of anti-spike protein antibodies was observed in vaccinated patients; however, these titres were significantly lower against B.1.617.2 than the wildtype vaccine strain.

DISCUSSION

The mRNA vaccines are highly effective at preventing symptomatic and severe COVID-19 associated with B.1.617.2 infection. Vaccination is associated with faster decline in viral RNA load and a robust serological response. Vaccination remains a key strategy for control of the COVID-19 pandemic.

Gut Ruminococcaceae levels at baseline correlate with risk of antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) affects a significant proportion of patients receiving antibiotics. We sought to understand if differences in the gut microbiome would influence the development of AAD. We administered a 3-day course of amoxicillin-clavulanate to 30 healthy adult volunteers, and analyzed their stool microbiome, using 16S rRNA gene sequencing, at baseline and up to 4 weeks post antibiotic administration. Lower levels of gut Ruminococcaceae were significantly and consistently observed from baseline until day 7 in participants who developed AAD. Overall, participants who developed AAD experienced a greater decrease in microbial diversity. The probability of AAD could be predicted based on qPCR-derived levels of Faecalibacterium prausnitzii at baseline. Our findings suggest that a lack of gut Ruminococcaceae influences development of AAD. Quantification of F. prausnitzii in stool prior to antibiotic administration may help identify patients at risk of AAD, and aid clinicians in devising individualized treatment regimens to minimize such adverse effects.

Data-Driven Analysis of COVID-19 Reveals Persistent Immune Abnormalities in Convalescent Severe Individuals

Severe SARS-CoV-2 infection can trigger uncontrolled innate and adaptive immune responses, which are commonly associated with lymphopenia and increased neutrophil counts. However, whether the immune abnormalities observed in mild to severely infected patients persist into convalescence remains unclear. Herein, comparisons were drawn between the immune responses of COVID-19 infected and convalescent adults. Strikingly, survivors of severe COVID-19 had decreased proportions of NKT and Vδ2 T cells, and increased proportions of low-density neutrophils, IgA+/CD86+/CD123+ non-classical monocytes and hyperactivated HLADR+CD38+ CD8+ T cells, and elevated levels of pro-inflammatory cytokines such as hepatocyte growth factor and vascular endothelial growth factor A, long after virus clearance. Our study suggests potential immune correlates of "long COVID-19", and defines key cells and cytokines that delineate true and quasi-convalescent states.

626 Dissecting the spatial heterogeneity of SARS-CoV-2-infected tumour microenvironment reveals a lymphocyte-dominant immune response in a HBV-associated HCC patient with COVID-19 history

Background

We previously reported the presence of SARS-CoV-2 RNA in the hepatic tissues of recovered patients1 but the spatial immune profile of SARS-CoV-2 infection remains poorly understood. To address this, here we performed deep spatial profiling in tumour-adjacent normal hepatic tissue from a HBV-associated hepatocellular carcinoma (HCC) patient with history of COVID-19.

Methods

We obtained tissue from curative resection of a HCC patient 85 days post-recovery from COVID-19. Spatial immune profiling was performed by multiplex immunohistochemistry (mIHC)2 and more deeply using the Visium spatial transcriptomics platform complemented with signatures derived from single-cell RNA sequencing (scRNA-seq) and published signatures.

Results

SARS-CoV-2 nucleocapsid and spike proteins were detected in a tumour-adjacent normal hepatic section in a spatially-restricted pattern (figure 1A and B) and higher abundance of lymphocytes but not macrophages were observed in regions with virus detection (figure 1C).We employed spatial transcriptomics and scRNA-seq to further characterize the immune microenvironment of SARS-CoV-2 post-infection. Unsupervised clustering and automatic annotation3 of Visium spots revealed that the distribution of SARS-CoV-2 viral proteins partially coincided with a memory T-cell signature (figure 1D). Quantification of Visium transcriptomic spots using an independent transcriptomic signature based on genes differentially upregulated in immune cells in SARS-CoV-2 infection4 (figure 1E) resulted in an enrichment pattern similar to the SARS-CoV-2 protein distribution. Additionally, a signature derived from scRNA-seq of hepatic tumour-infiltrating lymphocytes after ex vivo peptide stimulation using a pool of SARS-CoV-2 peptides showed a strongly associated distribution, in line with a SARS-CoV2-specific immune response5 whereas that from using a pool of HBV peptides resulted in an anti-correlated distribution (figure 1F). These illustrate the ability of spatial transcriptomics to quantify with microenvironment-level resolution the SARS-CoV-2-specific immune response.Recapitulating the mIHC protein data, deconvolution of immune populations6 revealed marked spatial associations between SARS-CoV-2 viral presence and the distributions of lymphocytes but not of macrophages (figure 1G).

Conclusions

We believe this is the first deep profiling report of non-post-mortem samples which adopts a multi-modal approach combining mIHC, spatial transcriptomics, and transcriptomic signatures derived from scRNA-seq to interrogate the in situ immune response to viral infection. Applying this to SARS-CoV-2 infection, we detected tissue spatial heterogeneity in viral presence and an associated lymphocyte-dominant immune response in the COVID-19-recovered patient, in contrast to post-mortem observations of scarce lymphocytes in cases of severe COVID-19.7 Ongoing work including further validation of the findings in local and overseas cohorts and their correlation with patient clinical outcomes.

References

Cheung CCL, et al. Residual SARS-CoV-2 viral antigens detected in GI and hepatic tissues from five recovered patients with COVID-19. Gut, p. gutjnl-2021-324280, 2021. doi: 10.1136/gutjnl-2021-324280.

Lim JCT, et al. An automated staining protocol for seven-colour immunofluorescence of human tissue sections for diagnostic and prognostic use. Pathology (Phila.) 2018;50(3):333–341. doi: 10.1016/j.pathol.2017.11.087.

Shao X, Liao J, Lu X, Xue R, Ai N, Fan X. scCATCH: automatic annotation on cell types of Clusters from Single-Cell RNA Sequencing Data. iScience 2020;23(3):100882, doi: 10.1016/j.isci.2020.100882.

Lee JS, et al. Immunophenotyping of COVID-19 and influenza highlights the role of type I interferons in development of severe COVID-19. Sci Immunol 2020;5(49):p.eabd1554. doi: 10.1126/sciimmunol.abd1554.

Schub D, et al. High levels of SARS-CoV-2–specific T cells with restricted functionality in severe courses of COVID-19. JCI Insight 2020;5(20):p.e142167. doi: 10.1172/jci.insight.142167.

Newman AM, et al. Robust enumeration of cell subsets from tissue expression profiles. Nat Methods 2015;12(5):453–457. doi: 10.1038/nmeth.3337.

Wang Y, et al. SARS-CoV-2 infection of the liver directly contributes to hepatic impairment in patients with COVID-19. J Hepatol 2020;73(4):807–816. doi: 10.1016/j.jhep.2020.05.002.

Ethics Approval

This study was approved by the SingHealth Centralised Institutional Review Board (reference number: 2019/2653)

Abstract 626 Figure 1

Spatial heterogeneity of SARS-CoV-2 infection uncovers an association with a dominant lymphocytic response

Robust Virus-Specific Adaptive Immunity in COVID-19 Patients with SARS-CoV-2 Δ382 Variant Infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) that have become dominant as the pandemic progresses bear the ORF8 mutation together with multiple spike mutations. A 382-nucleotide deletion (Δ382) in the ORF7b and ORF8 regions has been associated with milder disease phenotype and less systemic inflammation in COVID-19 patients. However, its impact on host immunity against SARS-CoV-2 remains undefined. Here, RNA-sequencing was performed to elucidate whole blood transcriptomic profiles and identify contrasting immune signatures between patients infected with either wildtype or Δ382 SARS-CoV-2 variant. Interestingly, the immune landscape of Δ382 SARS-CoV-2 infected patients featured an increased adaptive immune response, evidenced by enrichment of genes related to T cell functionality, a more robust SARS-CoV-2-specific T cell immunity, as well as a more rapid antibody response. At the molecular level, eukaryotic initiation factor 2 signaling was found to be upregulated in patients bearing Δ382, and its associated genes were correlated with systemic levels of T cell-associated and pro-inflammatory cytokines. This study provides more in-depth insight into the host–pathogen interactions of ORF8 with great promise as a therapeutic target to combat SARS-CoV-2 infection.

Meropenem Versus Piperacillin-Tazobactam for Definitive Treatment of Bloodstream Infections Caused by AmpC β-Lactamase-Producing Enterobacter spp, Citrobacter freundii, Morganella morganii, Providencia spp, or Serratia marcescens: A Pilot Multicenter Randomized Controlled Trial (MERINO-2)

Background

Carbapenems are recommended treatment for serious infections caused by AmpC-producing gram-negative bacteria but can select for carbapenem resistance. Piperacillin-tazobactam may be a suitable alternative.

Methods

We enrolled adult patients with bloodstream infection due to chromosomal AmpC producers in a multicenter randomized controlled trial. Patients were assigned 1:1 to receive piperacillin-tazobactam 4.5 g every 6 hours or meropenem 1 g every 8 hours. The primary efficacy outcome was a composite of death, clinical failure, microbiological failure, and microbiological relapse at 30 days.

Results

Seventy-two patients underwent randomization and were included in the primary analysis population. Eleven of 38 patients (29%) randomized to piperacillin-tazobactam met the primary outcome compared with 7 of 34 patients (21%) in the meropenem group (risk difference, 8% [95% confidence interval {CI}, –12% to 28%]). Effects were consistent in an analysis of the per-protocol population. Within the subcomponents of the primary outcome, 5 of 38 (13%) experienced microbiological failure in the piperacillin-tazobactam group compared to 0 of 34 patients (0%) in the meropenem group (risk difference, 13% [95% CI, 2% to 24%]). In contrast, 0% vs 9% of microbiological relapses were seen in the piperacillin-tazobactam and meropenem arms, respectively. Susceptibility to piperacillin-tazobactam and meropenem using broth microdilution was found in 96.5% and 100% of isolates, respectively. The most common AmpC β-lactamase genes identified were bla_CMY-2, bla_DHA-17, bla_CMH-3, and bla_ACT-17. No ESBL, OXA, or other carbapenemase genes were identified.

Conclusions

Among patients with bloodstream infection due to AmpC producers, piperacillin-tazobactam may lead to more microbiological failures, although fewer microbiological relapses were seen.

Clinical Trials Registration

NCT02437045.

Cefazolin versus ceftriaxone as definitive treatment for Klebsiella pneumoniae bacteraemia: a retrospective multicentre study in Singapore

BACKGROUND

Ceftriaxone is the preferred treatment for bacteraemia caused by non-MDR (antibiotic-susceptible) Klebsiella pneumoniae. Excessive and widespread ceftriaxone use creates selection pressure for ESBLs. Cefazolin is an alternative, although there are theoretical concerns that SHV-1 β-lactamase in K. pneumoniae may inactivate cefazolin in an inoculum-dependent manner.

OBJECTIVES

In this retrospective study, we investigated the outcomes in K. pneumoniae bacteraemia patients treated with IV cefazolin versus IV ceftriaxone as definitive therapy.

METHODS

A total of 917 patients infected with K. pneumoniae from 1 January to 31 December 2016 in three public acute care hospitals in Singapore were screened for study eligibility. Consecutive unique episodes of monomicrobial bacteraemia caused by cefazolin- and/or ceftriaxone-susceptible K. pneumoniae were analysed (n = 284).

RESULTS

There were 143 patients (50.4%) in the cefazolin group and 141 patients (49.6%) in the ceftriaxone group. Demographics, baseline illness severity and risk factors for healthcare-associated bacteraemia were comparable in the two treatment groups. The primary outcome of 28 day all-cause mortality was not significantly different between the cefazolin and ceftriaxone groups (10.5% versus 7.1%, P = 0.403). Both in the crude analysis and using a multivariable logistic regression model with inverse probability weighting based on propensity score, cefazolin treatment was not associated with increased risk of 28 day mortality (OR 1.51 with ceftriaxone as the reference group, 95% CI 0.67-3.53; adjusted OR 1.55, 95% CI 0.33-7.40).

CONCLUSIONS

Cefazolin may be a ceftriaxone-sparing alternative treatment for antibiotic-susceptible K. pneumoniae bacteraemia. This observation may provide sufficient clinical equipoise for a randomized controlled trial.

Differential Cytokine Responses in Hospitalized COVID-19 Patients Limit Efficacy of Remdesivir

A significant proportion of COVID-19 patients will progress to critical illness requiring invasive mechanical ventilation. This accentuates the need for a therapy that can reduce the severity of COVID-19. Clinical trials have shown the effectiveness of remdesivir in shortening recovery time and decreasing progression to respiratory failure and mechanical ventilation. However, some studies have highlighted its lack of efficacy in patients on high-flow oxygen and mechanical ventilation. This study uncovers some underlying immune response differences between responders and non-responders to remdesivir treatment. Immunological analyses revealed an upregulation of tissue repair factors BDNF, PDGF-BB and PIGF-1, as well as an increase in ratio of Th2-associated cytokine IL-4 to Th1-associated cytokine IFN-γ. Serological profiling of IgG subclasses corroborated this observation, with significantly higher magnitude of increase in Th2-associated IgG2 and IgG4 responses. These findings help to identify the mechanisms of immune regulation accompanying successful remdesivir treatment in severe COVID-19 patients.

Early T cell and binding antibody responses are associated with COVID-19 RNA vaccine efficacy onset

BACKGROUND

RNA vaccines against coronavirus disease 2019 (COVID-19) have demonstrated ∼95% efficacy in phase III clinical trials. Although complete vaccination consisted of 2 doses, the onset of protection for both licensed RNA vaccines was observed as early as 12 days after a single dose. The adaptive immune response that coincides with this onset of protection could represent the necessary elements of immunity against COVID-19.

METHODS

Serological and T cell analysis was performed in a cohort of 20 healthcare workers after receiving the first dose of the Pfizer/BioNTech BNT162b2 vaccine. The primary endpoint was the adaptive immune responses detectable at days 7 and 10 after dosing.

FINDINGS

Spike-specific T cells and binding antibodies were detectable 10 days after the first dose of the vaccine, in contrast to receptor-blocking and severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) neutralizing antibodies, which were mostly undetectable at this early time point.

CONCLUSIONS

Our findings suggest that early T cell and binding antibody responses, rather than either receptor-blocking or virus neutralizing activity, induced early protection against COVID-19.

FUNDING

The study was funded by a generous donation from The Hour Glass to support COVID-19 research.

Asymptomatic COVID-19: disease tolerance with efficient anti-viral immunity against SARS-CoV-2

The immune responses and mechanisms limiting symptom progression in asymptomatic cases of SARS-CoV-2 infection remain unclear. We comprehensively characterized transcriptomic profiles, cytokine responses, neutralization capacity of antibodies, and cellular immune phenotypes of asymptomatic patients with acute SARS-CoV-2 infection to identify potential protective mechanisms. Compared to symptomatic patients, asymptomatic patients had higher counts of mature neutrophils and lower proportion of CD169+ expressing monocytes in the peripheral blood. Systemic levels of pro-inflammatory cytokines were also lower in asymptomatic patients, accompanied by milder pro-inflammatory gene signatures. Mechanistically, a more robust systemic Th2 cell signature with a higher level of virus-specific Th17 cells and a weaker yet sufficient neutralizing antibody profile against SARS-CoV-2 was observed in asymptomatic patients. In addition, asymptomatic COVID-19 patients had higher systemic levels of growth factors that are associated with cellular repair. Together, the data suggest that asymptomatic patients mount less pro-inflammatory and more protective immune responses against SARS-CoV-2 indicative of disease tolerance. Insights from this study highlight key immune pathways that could serve as therapeutic targets to prevent disease progression in COVID-19.

A single dose of self-transcribing and replicating RNA-based SARS-CoV-2 vaccine produces protective adaptive immunity in mice

A self-transcribing and replicating RNA (STARR)-based vaccine (LUNAR-COV19) has been developed to prevent SARS-CoV-2 infection. The vaccine encodes an alphavirus-based replicon and the SARS-CoV-2 full-length spike glycoprotein. Translation of the replicon produces a replicase complex that amplifies and prolongs SARS-CoV-2 spike glycoprotein expression. A single prime vaccination in mice led to robust antibody responses, with neutralizing antibody titers increasing up to day 60. Activation of cell-mediated immunity produced a strong viral antigen-specific CD8+ T lymphocyte response. Assaying for intracellular cytokine staining for interferon (IFN)γ and interleukin-4 (IL-4)-positive CD4+ T helper (Th) lymphocytes as well as anti-spike glycoprotein immunoglobulin G (IgG)2a/IgG1 ratios supported a strong Th1-dominant immune response. Finally, single LUNAR-COV19 vaccination at both 2 μg and 10 μg doses completely protected human ACE2 transgenic mice from both mortality and even measurable infection following wild-type SARS-CoV-2 challenge. Our findings collectively suggest the potential of LUNAR-COV19 as a single-dose vaccine.

Signatures of mast cell activation are associated with severe COVID-19

Lung inflammation is a hallmark of Coronavirus disease 2019 (COVID-19) in severely ill patients and the pathophysiology of disease is thought to be immune-mediated. Mast cells (MCs) are polyfunctional immune cells present in the airways, where they respond to certain viruses and allergens, often promoting inflammation. We observed widespread degranulation of MCs during acute and unresolved airway inflammation in SARS-CoV-2-infected mice and non-human primates. In humans, transcriptional changes in patients requiring oxygen supplementation also implicated cells with a MC phenotype. MC activation in humans was confirmed, through detection of the MC-specific protease, chymase, levels of which were significantly correlated with disease severity. These results support the association of MC activation with severe COVID-19, suggesting potential strategies for intervention.

Oral vs Intravenous Antibiotics for Patients With Klebsiella pneumoniae Liver Abscess: A Randomized, Controlled Noninferiority Study

BACKGROUND

Klebsiella pneumoniae liver abscess (KLA) is emerging worldwide due to hypermucoviscous strains with a propensity for metastatic infection. Treatment includes drainage and prolonged intravenous antibiotics. We aimed to determine whether oral antibiotics were noninferior to continued intravenous antibiotics for KLA.

METHODS

This noninferiority, parallel group, randomized, clinical trial recruited hospitalized adults with liver abscess and K. pneumoniae isolated from blood or abscess fluid who had received ≤7 days of effective antibiotics at 3 sites in Singapore. Patients were randomized 1:1 to oral (ciprofloxacin) or intravenous (ceftriaxone) antibiotics for 28 days. If day 28 clinical response criteria were not met, further oral antibiotics were prescribed until clinical response was met. The primary endpoint was clinical cure assessed at week 12 and included a composite of absence of fever in the preceding week, C-reactive protein <20 mg/L, and reduction in abscess size. A noninferiority margin of 12% was used.

RESULTS

Between November 2013 and October 2017, 152 patients (mean age, 58.7 years; 25.7% women) were recruited, following a median 5 days of effective intravenous antibiotics. A total of 106 (69.7%) underwent abscess drainage; 71/74 (95.9%) randomized to oral antibiotics met the primary endpoint compared with 72/78 (92.3%) randomized to intravenous antibiotics (risk difference, 3.6%; 2-sided 95% confidence interval, -4.9% to 12.8%). Effects were consistent in the per-protocol population. Nonfatal serious adverse events occurred in 12/72 (16.7%) in the oral group and 13/77 (16.9%) in the intravenous group.

CONCLUSIONS

Oral antibiotics were noninferior to intravenous antibiotics for the early treatment of KLA.

CLINICAL TRIALS REGISTRATION

NCT01723150.

Author Correction: The higher prevalence of extended spectrum beta-lactamases among Escherichia coli ST131 in Southeast Asia is driven by expansion of a single, locally prevalent subclone

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Clinical features and predictors of severity in COVID-19 patients with critical illness in Singapore

We aim to describe a case series of critically and non-critically ill COVID-19 patients in Singapore. This was a multicentered prospective study with clinical and laboratory details. Details for fifty uncomplicated COVID-19 patients and ten who required mechanical ventilation were collected. We compared clinical features between the groups, assessed predictors of intubation, and described ventilatory management in ICU patients. Ventilated patients were significantly older, reported more dyspnea, had elevated C-reactive protein and lactate dehydrogenase. A multivariable logistic regression model identified respiratory rate (aOR 2.83, 95% CI 1.24–6.47) and neutrophil count (aOR 2.39, 95% CI 1.34–4.26) on admission as independent predictors of intubation with area under receiver operating characteristic curve of 0.928 (95% CI 0.828–0.979). Median APACHE II score was 19 (IQR 17–22) and PaO2/FiO2 ratio before intubation was 104 (IQR 89–129). Median peak FiO2 was 0.75 (IQR 0.6–1.0), positive end-expiratory pressure 12 (IQR 10–14) and plateau pressure 22 (IQR 18–26) in the first 24 h of ventilation. Median duration of ventilation was 6.5 days (IQR 5.5–13). There were no fatalities. Most COVID-19 patients in Singapore who required mechanical ventilation because of ARDS were extubated with no mortality.

Association of SARS-CoV-2 clades with clinical, inflammatory and virologic outcomes: An observational study

BACKGROUND

Host determinants of severe coronavirus disease 2019 include advanced age, comorbidities and male sex. Virologic factors may also be important in determining clinical outcome and transmission rates, but limited patient-level data is available.

METHODS

We conducted an observational cohort study at seven public hospitals in Singapore. Clinical and laboratory data were collected and compared between individuals infected with different SARS-CoV-2 clades. Firth's logistic regression was used to examine the association between SARS-CoV-2 clade and development of hypoxia, and quasi-Poisson regression to compare transmission rates. Plasma samples were tested for immune mediator levels and the kinetics of viral replication in cell culture were compared.

FINDINGS

319 patients with PCR-confirmed SARS-CoV-2 infection had clinical and virologic data available for analysis. 29 (9%) were infected with clade S, 90 (28%) with clade L/V, 96 (30%) with clade G (containing D614G variant), and 104 (33%) with other clades 'O' were assigned to lineage B.6. After adjusting for age and other covariates, infections with clade S (adjusted odds ratio (aOR) 0·030 (95% confidence intervals (CI): 0·0002-0·29)) or clade O (B·6) (aOR 0·26 (95% CI 0·064-0·93)) were associated with lower odds of developing hypoxia requiring supplemental oxygen compared with clade L/V. Patients infected with clade L/V had more pronounced systemic inflammation with higher concentrations of pro-inflammatory cytokines, chemokines and growth factors. No significant difference in the severity of clade G infections was observed (aOR 0·95 (95% CI: 0·35-2·52). Though viral loads were significantly higher, there was no evidence of increased transmissibility of clade G, and replicative fitness in cell culture was similar for all clades.

INTERPRETATION

Infection with clades L/V was associated with increased severity and more systemic release of pro-inflammatory cytokines. Infection with clade G was not associated with changes in severity, and despite higher viral loads there was no evidence of increased transmissibility.

Highly functional virus-specific cellular immune response in asymptomatic SARS-CoV-2 infection

The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between antiviral and inflammatory features. SARS-CoV-2–specific T cells in individuals who clear SARS-CoV-2 without symptoms could reveal nonpathological yet protective characteristics. We longitudinally studied SARS-CoV-2–specific T cells in a cohort of asymptomatic (n = 85) and symptomatic (n = 75) COVID-19 patients after seroconversion. We quantified T cells reactive to structural proteins (M, NP, and Spike) using ELISpot and cytokine secretion in whole blood. Frequencies of SARS-CoV-2–specific T cells were similar between asymptomatic and symptomatic individuals, but the former showed an increased IFN-γ and IL-2 production. This was associated with a proportional secretion of IL-10 and proinflammatory cytokines (IL-6, TNF-α, and IL-1β) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2–specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2–infected individuals are not characterized by weak antiviral immunity; on the contrary, they mount a highly functional virus-specific cellular immune response.

Temporal dynamics of the host molecular responses underlying severe COVID-19 progression and disease resolution

BACKGROUND

The coronavirus disease-19 (COVID-19) pandemic has cost lives and economic hardships globally. Various studies have found a number of different factors, such as hyperinflammation and exhausted/suppressed T cell responses to the etiological SARS coronavirus-2 (SARS-CoV-2), being associated with severe COVID-19. However, sieving the causative from associative factors of respiratory dysfunction has remained rudimentary.

METHODS

We postulated that the host responses causative of respiratory dysfunction would track most closely with disease progression and resolution and thus be differentiated from other factors that are statistically associated with but not causative of severe COVID-19. To track the temporal dynamics of the host responses involved, we examined the changes in gene expression in whole blood of 6 severe and 4 non-severe COVID-19 patients across 15 different timepoints spanning the nadir of respiratory function.

FINDINGS

We found that neutrophil activation but not type I interferon signaling transcripts tracked most closely with disease progression and resolution. Moreover, transcripts encoding for protein phosphorylation, particularly the serine-threonine kinases, many of which have known T cell proliferation and activation functions, were increased after and may thus contribute to the upswing of respiratory function. Notably, these associative genes were targeted by dexamethasone, but not methylprednisolone, which is consistent with efficacy outcomes in clinical trials.

INTERPRETATION

Our findings suggest neutrophil activation as a critical factor of respiratory dysfunction in COVID-19. Drugs that target this pathway could be potentially repurposed for the treatment of severe COVID-19.

FUNDING

This study was sponsored in part by a generous gift from The Hour Glass. EEO and JGL are funded by the National Medical Research Council of Singapore, through the Clinician Scientist Awards awarded by the National Research Foundation of Singapore.

Early induction of functional SARS-CoV-2-specific T cells associates with rapid viral clearance and mild disease in COVID-19 patients

Virus-specific humoral and cellular immunity act synergistically to protect the host from viral infection. We interrogate the dynamic changes of virological and immunological parameters in 12 patients with symptomatic acute SARS-CoV-2 infection from disease onset to convalescence or death. We quantify SARS-CoV-2 viral RNA in the respiratory tract in parallel with antibodies and circulating T cells specific for various structural (nucleoprotein [NP], membrane [M], ORF3a, and spike) and non-structural (ORF7/8, NSP7, and NSP13) proteins. Although rapid induction and quantity of humoral responses associate with an increase in disease severity, early induction of interferon (IFN)-γ-secreting SARS-CoV-2-specific T cells is present in patients with mild disease and accelerated viral clearance. These findings provide support for the prognostic value of early functional SARS-CoV-2-specific T cells with important implications in vaccine design and immune monitoring.

Sensitive detection of total anti-Spike antibodies and isotype switching in asymptomatic and symptomatic individuals with COVID-19

Early detection of infection is crucial to limit the spread of coronavirus disease 2019 (COVID-19). Here we develop a flow cytometry-based assay to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein antibodies in individuals with COVID-19. The assay detects specific immunoglobulin M (IgM), IgA, and IgG in individuals with COVID-19 and also acquisition of all IgG subclasses, with IgG1 being the most dominant. The antibody response is significantly higher at a later stage of infection. Furthermore, asymptomatic individuals with COVID-19 also develop specific IgM, IgA, and IgG, with IgG1 being the most dominant subclass. Although the antibody levels are lower in asymptomatic infection, the assay is highly sensitive and detects 97% of asymptomatic infections. These findings demonstrate that the assay can be used for serological analysis of symptomatic and asymptomatic infections, which may otherwise remain undetected.

Flow cytometry assay detects specific antibodies in symptomatic individuals with COVID-19

Asymptomatic individuals with COVID-19 also develop specific antibodies

IgG1 is the dominant IgG subclass in symptomatic and asymptomatic individuals

The assay is highly sensitive and detects 97% of asymptomatic infections

Validation of self-collected buccal swab and saliva as a diagnostic tool for COVID-19

BACKGROUND

Effective management of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires large-scale testing to identify and isolate infectious carriers. Self-administered buccal swab and saliva collection are convenient, painless, and safe alternatives to the current healthcare worker (HCW)-collected nasopharyngeal swab (NPS).

METHODS

A cross-sectional single-centre study was conducted on 42 participants who had tested positive for SARS-CoV-2 via an NPS within the past 7 days. Real-time polymerase chain reaction (RT-PCR) was performed and cycle threshold (Ct) values were obtained for each test. The positive percent agreement (PPA), negative percent agreement (NPA), and overall agreement (OA) were calculated for the saliva samples and buccal swabs, and compared with NPS.

RESULTS

Among the 42 participants, 73.8% (31/42) tested positive by any one of the three tests. With reference to NPS, the saliva test had PPA 66.7%, NPA 91.7%, and OA 69.0%; the buccal swab had PPA 56.7%, NPA 100%, and OA 73.8%.

CONCLUSION

Self-collected saliva tests and buccal swabs showed only moderate agreement with HCW-collected NPS. Primary screening for SARS-CoV-2 may be performed with a saliva test or buccal swab, with a negative test warranting a confirmatory NPS to avoid false-negatives, minimize discomfort, and reduce the risk of spread to the community and HCWs.

Pregnancy Outcomes in COVID-19: A Prospective Cohort Study in Singapore

INTRODUCTION

Pregnant women are reported to be at increased risk of severe coronavirus disease 2019 (COVID-19) due to underlying immunosuppression during pregnancy. However, the clinical course of COVID-19 in pregnancy and risk of vertical and horizontal transmission remain relatively unknown. We aim to describe and evaluate outcomes in pregnant women with COVID-19 in Singapore.

METHODS

Prospective observational study of 16 pregnant patients admitted for COVID-19 to 4 tertiary hospitals in Singapore. Outcomes included severe disease, pregnancy loss, and vertical and horizontal transmission.

RESULTS

Of the 16 patients, 37.5%, 43.8% and 18.7% were infected in the first, second and third trimesters, respectively. Two gravidas aged ≥35 years (12.5%) developed severe pneumonia; one patient (body mass index 32.9kg/m2) required transfer to intensive care. The median duration of acute infection was 19 days; one patient remained reverse transcription polymerase chain reaction (RT-PCR) positive >11 weeks from diagnosis. There were no maternal mortalities. Five pregnancies produced term live-births while 2 spontaneous miscarriages occurred at 11 and 23 weeks. RT-PCR of breast milk and maternal and neonatal samples taken at birth were negative; placenta and cord histology showed non-specific inflammation; and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific immunoglobulins were elevated in paired maternal and umbilical cord blood (n=5).

CONCLUSION

The majority of COVID-19 infected pregnant women had mild disease and only 2 women with risk factors (obesity, older age) had severe infection; this represents a slightly higher incidence than observed in age-matched non-pregnant women. Among the women who delivered, there was no definitive evidence of mother-to-child transmission via breast milk or placenta.

557. Impact of Concomitant Hydroxychloroquine Use on Safety and Efficacy of Remdesivir in Moderate COVID-19 Patients

Background

Remdesivir (RDV) has been shown to shorten recovery time and was well tolerated in patients with severe COVID-19. Hydroxychloroquine (HQN) is an experimental treatment for COVID-19. Effects of coadministration of HQN with RDV have not been studied and are relevant given the long half-life (~22 days) of HQN. We report the impact of concomitant HQN and RDV use on clinical outcomes and safety in patients with moderate COVID-19.

Methods

We enrolled hospitalized patients with confirmed SARS-CoV-2 infection, oxygen saturation >94% on room air, and radiological evidence of pneumonia. Patients were randomized 1:1:1 to receive 5d or 10d of intravenous RDV once daily plus standard of care (SoC), or SoC only. We compared patients on concomitant HQN (HQN^pos) vs not (HQN^neg). Clinical recovery was evaluated using Cox proportional hazards. Covariate adjustment included age, sex, race, region, symptom duration, oxygen support status and obesity. Recovery and adverse events (AEs) were assessed through death, discharge, or d14.

Results

Of 584 patients, 199 (34%) received HQN (5d RDV: n=57 [30%]; 10d RDV, n=49 [25%]; SoC: n=93 [47%]). Through median follow-up of 13d (range 1-41d), HQN^pos patients on 5d or 10d RDV had a lower recovery rate (adjusted HR [95% CI] 0.78 [0.59, 1.03], p=0.09) with longer median time to recovery (8 vs 6 days) compared to HQN^neg. HQN^pos compared to HQN^neg patients in 5d RDV showed a trend of reduced recovery rate (HR: 0.69 [0.45,1.04], p=0.080); such an effect was not observed in 10d RDV or SoC (Table 1). More HQN^pos than HQN^neg patients had AEs in RDV (5/10d) or SoC arms evaluated separately, and all arms combined. This difference was significant for AEs and SAEs for all arms combined after covariate adjustment (Table 2).

Table 1.

Table 2.

Conclusion

In moderate COVID-19 patients, concomitant HQN may delay recovery on RDV and showed no impact on recovery with SoC alone. The AE profile of HQN^pos patients was worse than that observed for HQN^neg patients, regardless of RDV treatment.

Disclosures

Jose Ramon Arribas, MD, Alexa (Advisor or Review Panel member, Speaker’s Bureau, Other Financial or Material Support, Personal fees)Gilead Sciences Inc. (Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau, Other Financial or Material Support, Personal fees)Janssen (Advisor or Review Panel member, Speaker’s Bureau, Other Financial or Material Support, Personal fees)Merck (Advisor or Review Panel member, Speaker’s Bureau, Other Financial or Material Support, Personal fees)Viiv Healthcare (Advisor or Review Panel member, Speaker’s Bureau, Other Financial or Material Support, Personal fees) Jose Ramon Arribas, MD, NO DISCLOSURE DATA Arun J. Sanyal, MD, AbbVie (Consultant)Akarna (Shareholder)Amarin (Consultant)Ardelyx (Consultant)Astra Zeneca (Consultant, Research Grant or Support)Boehringer (Consultant)Bristol Myers Squibb (Research Grant or Support)Conatus (Consultant)Cumberland (Research Grant or Support)Durect (Shareholder)Elsevier (Other Financial or Material Support, Royalties)Exhalenz (Shareholder)Fibrogen (Consultant)Genfit (Shareholder)Gilead Sciences Inc. (Consultant, Scientific Research Study Investigator, Research Grant or Support)Haemoshear (Shareholder)Indalo (Shareholder)Intercept (Research Grant or Support)Jannsen (Consultant)Lilly (Consultant)Malinckrodt (Research Grant or Support)Merck (Research Grant or Support)Nimbus (Consultant)Nitto Denko (Consultant)Novartis (Consultant)Pfizer (Consultant)Salix (Consultant)Sanyal Biotechnology (Employee, Shareholder, Other Financial or Material Support, President)Shire (Research Grant or Support)Takeda (Consultant)Tiziana (Shareholder)Tobira (Consultant)UptoDate (Other Financial or Material Support, Royalties)Zafgen (Consultant) Bum Sik Chin, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) Bum Sik Chin, MD, NO DISCLOSURE DATA Shirin Kalimuddin, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) Stefan Schreiber, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) Emon Elboudwarej, PhD, Gilead Sciences Inc. (Employee, Shareholder) Yuan Tian, PhD, Gilead Sciences Inc. (Employee, Shareholder) Robert H. Hyland, MD, Gilead Sciences Inc. (Employee, Shareholder) Devi SenGupta, MD, Gilead Sciences Inc. (Employee, Shareholder) Anand Chokkalingam, PhD, Gilead Sciences (Employee) Anu Osinusi, MD, Gilead Sciences (Employee) Diana M. Brainard, MD, Gilead Sciences (Employee) Christoph Lübbert, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) David Chien Boon Lye, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) David Chien Boon Lye, MD, NO DISCLOSURE DATA Judith A. Aberg, MD, Theratechnology (Consultant) Enrique Navas Elorza, MD, Gilead Sciences Inc. (Scientific Research Study Investigator) Karen T. Tashima, MD, Bristol-Myers Squibb (Research Grant or Support)Gilead Sciences Inc. (Grant/Research Support, Scientific Research Study Investigator)GlaxoSmithKline (Research Grant or Support)Merck (Research Grant or Support)Tibotec (Research Grant or Support)Viiv Healthcare (Research Grant or Support) Mark McPhail, MD, Gilead Sciences Inc. (Scientific Research Study Investigator)

18F-fluorodeoxyglucose positron emission tomography as a window into human dengue pathophysiology

In mouse models of dengue virus (DENV) infection, ¹⁸F-FDG PET is able to sensitively detect tissue-specific sites of inflammation and disease activity, as well as track therapeutic response to anti- DENV agents. However, the use of ¹⁸F-FDG PET to study the pathogenesis of inflammation and disease activity in DENV infection in humans, has not been clinically validated. Here we report the ¹⁸F-FDG PET imaging results of two patients during the febrile phase of acute DENV infection, paired with serial serum viral load, NS1 and proinflammatory cytokine measurements. Our findings demonstrate that ¹⁸F-FDG PET is able to sensitively detect and quantify organ-specific inflammation in the lymph nodes and spleen, in classic acute dengue fever. This raises the potential for ¹⁸F-FDG PET to be used as a research tool that may provide further insights into disease pathogenesis.

Radiographic features of COVID-19 based on an initial cohort of 96 patients in Singapore

INTRODUCTION

Chest radiographs (CXR) are widely used for the screening and management of the coronavirus disease 2019 (COVID-19). This paper determinates the radiographic features of COVID-19 based on an initial national cohort of patients.

METHODS

This is a retrospective review of swab-positive COVID-19 patients admitted to four different hospitals in Singapore between 22 January and 9 March 2020. Initial and follow-up CXR were reviewed by three experienced radiologists to identify the predominant pattern and distribution of lung parenchymal abnormalities.

RESULTS

In total, 347 CXR of 96 patients were reviewed. Initial CXR were abnormal in 41 out of 96 patients (42.7%). The mean time from onset of symptoms to CXR abnormality was 5.3 (range 1-21) days. The predominant pattern of lung abnormality was ground-glass opacity on initial CXR (51.2%) and consolidation on follow-up CXR (51.0%). Multifocal bilateral abnormalities in mixed central and peripheral distribution were seen in 63.4% and 59.2% of abnormal initial and follow-up CXR, respectively. The lower zones were involved in 90.2% of the initial CXR and 93.9% of the follow-up CXR.

CONCLUSION

In a cohort of swab-positive patients, including those identified from contact tracing, we found the incidence of CXR abnormality to be lower than previously reported. The most common pattern was ground-glass opacity or consolidation, but mixed central and peripheral involvement was more common than peripheral involvement alone.

Adenoviral Infections in Singapore: Should New Antiviral Therapies and Vaccines Be Adopted?

Background

A number of serious human adenovirus (HAdV) outbreaks have been recently reported: HAdV-B7 (Israel, Singapore, and USA), HAdV-B7d (USA and China), HAdV-D8, -D54, and -C2 (Japan), HAdV-B14p1 (USA, Europe, and China), and HAdV-B55 (China, Singapore, and France).

Methods

To understand the epidemiology of HAdV infections in Singapore, we studied 533 HAdV-positive clinical samples collected from 396 pediatric and 137 adult patients in Singapore from 2012 to 2018. Genome sequencing and phylogenetic analyses were performed to identify HAdV genotypes, clonal clusters, and recombinant or novel HAdVs.

Results

The most prevalent genotypes identified were HAdV-B3 (35.6%), HAdV-B7 (15.4%), and HAdV-E4 (15.2%). We detected 4 new HAdV-C strains and detected incursions with HAdV-B7 (odds ratio [OR], 14.6; 95% confidence interval [CI], 4.1–52.0) and HAdV-E4 (OR, 13.6; 95% CI, 3.9–46.7) among pediatric patients over time. In addition, immunocompromised patients (adjusted OR [aOR], 11.4; 95% CI, 3.8–34.8) and patients infected with HAdV-C2 (aOR, 8.5; 95% CI, 1.5–48.0), HAdV-B7 (aOR, 3.7; 95% CI, 1.2–10.9), or HAdV-E4 (aOR, 3.2; 95% CI, 1.1–8.9) were at increased risk for severe disease.

Conclusions

Singapore would benefit from more frequent studies of clinical HAdV genotypes to identify patients at risk for severe disease and help guide the use of new antiviral therapies, such as brincidofovir, and potential administration of HAdV 4 and 7 vaccine.