Association Between Infectious Diseases Consultation and Mortality in Hospitalized Patients With Gram-negative Bloodstream Infection: A Retrospective Population-wide Cohort Study.

OBJECTIVES: Data supporting routine infectious diseases (ID) consultation in gram-negative bloodstream infection (GN-BSI) are limited. We evaluated the association between ID consultation and mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario using linked health administrative databases. METHODS: Hospitalized adult patients with GN-BSI between April 2017 and December 2021 were included. The primary outcome was time to all-cause mortality censored at 30 days, analyzed using a mixed effects Cox proportional hazards model with hospital as a random effect. ID consultation 1-10 days after the first positive blood culture was treated as a time-varying exposure. RESULTS: Of 30 159 patients with GN-BSI across 53 hospitals, 11 013 (36.5%) received ID consultation. Median prevalence of ID consultation for patients with GN-BSI across hospitals was 35.0% with wide variability (range 2.7%-76.1%, interquartile range 19.6%-41.1%). In total, 1041 (9.5%) patients who received ID consultation died within 30 days, compared to 1797 (9.4%) patients without ID consultation. In the fully adjusted multivariable model, ID consultation was associated with mortality benefit (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] .77-.88, P < .0001; translating to absolute risk reduction of -3.8% or number needed to treat [NNT] of 27). Exploratory subgroup analyses of the primary outcome showed that ID consultation could have greater benefit in patients with high-risk features (nosocomial infection, polymicrobial or non-Enterobacterales infection, antimicrobial resistance, or non-urinary tract source). CONCLUSIONS: Early ID consultation was associated with reduced mortality in patients with GN-BSI. If resources permit, routine ID consultation for this patient population should be considered to improve patient outcomes.

Epidemiology and clinical relevance of persistent bacteraemia in patients with Gram-negative bloodstream infection: a retrospective cohort study.

OBJECTIVES: The risk factors and outcomes associated with persistent bacteraemia in Gram-negative bloodstream infection (GN-BSI) are not well described. We conducted a follow-on analysis of a retrospective population-wide cohort to characterize persistent bacteraemia in patients with GN-BSI. METHODS: We included all hospitalized patients >18 years old with GN-BSI between April 2017 and December 2021 in Ontario who received follow-up blood culture (FUBC) 2-5 days after the index positive blood culture. Persistent bacteraemia was defined as having a positive FUBC with the same Gram-negative organism as the index blood culture. We identified variables independently associated with persistent bacteraemia in a multivariable logistic regression model. We evaluated whether persistent bacteraemia was associated with increased odds of 30- and 90-day all-cause mortality using multivariable logistic regression models adjusted for potential confounders. RESULTS: In this study, 8807 patients were included; 600 (6.8%) had persistent bacteraemia. Having a permanent catheter, antimicrobial resistance, nosocomial infection, ICU admission, respiratory or skin and soft tissue source of infection, and infection by a non-fermenter or non-Enterobacterales/anaerobic organism were associated with increased odds of having persistent bacteraemia. The 30-day mortality was 17.2% versus 9.6% in those with and without persistent bacteraemia (aOR 1.65, 95% CI 1.29-2.11), while 90-day mortality was 25.5% versus 16.9%, respectively (aOR 1.53, 95% CI 1.24-1.89). Prevalence and odds of developing persistent bacteraemia varied widely depending on causative organism. CONCLUSIONS: Persistent bacteraemia is uncommon in GN-BSI but is associated with poorer outcomes. A validated risk stratification tool may be useful to identify patients with persistent bacteraemia.

Variant-specific IgA protects against Omicron infection.

BACKGROUND: The emergence of rapidly evolving SARS-CoV-2 variants, coupled with waning vaccine-induced immunity, has contributed to the rise of vaccine breakthrough infections. It is crucial to understand how vaccine-induced protection is mediated. METHODS: We examined two prospective cohorts of mRNA-vaccinated-and-boosted individuals during the Omicron wave of infection in Singapore. RESULTS: We found that, individuals, who remain uninfected over the follow-up period, had a higher variant-specific IgA, but not IgG, antibody response at 1-month post booster vaccination, compared with individuals who became infected. CONCLUSIONS: We conclude that IgA may have a potential contributory role in protection against Omicron infection.

Real-world effectiveness of sotrovimab and remdesivir for early treatment of high-risk hospitalized COVID-19 patients: A propensity score adjusted retrospective cohort study.

Early treatment of high-risk COVID-19 patients may prevent disease progression. However, there are limited data to support treatment of hospitalized or fully vaccinated patients with mild-to-moderate disease. In this retrospective cohort study, we studied the effect of early use of sotrovimab and remdesivir in high-risk hospitalized COVID-19 patients. We included PCR-confirmed COVID-19 patients admitted to the National Centre for Infectious Diseases who presented within the first 5 days of illness, and who were not requiring oxygen or ICU care at presentation. Sotrovimab- and remdesivir-treated groups were compared with control (no early treatment). A multiple propensity-score adjusted multivariable regression analysis was conducted with a composite primary endpoint of in-hospital deterioration (oxygen requirement, ICU admission, or mortality). Of 1118 patients, 841 were in the control group, 106 in the sotrovimab group and 169 in the remdesivir group. The median age was 63 years (IQR 46-74 years) and 505 (45.2%) were female. In unvaccinated patients, both remdesivir and sotrovimab treatment were protective (adjusted odds ratio [aOR] 0.19, 95% CI 0.064-0.60 and 0.18 [95% CI 0.066-0.47]), respectively. Contrarily, among the vaccinated patients there was no significant treatment effect with early remdesivir treatment (aOR 2.51, 95% CI 0.83-7.57, p = 0.10). Remdesivir and sotrovimab treatment, given early in the disease course to unvaccinated high-risk patients, was effective in reducing the risk of in-hospital deterioration and severe disease. This effect was not seen in fully vaccinated patients, which may be due to a small sample size or residual confounding.

Efficient recall of SARS-CoV-2 variant-reactive B cells and T responses in the elderly upon heterologous mRNA vaccines as boosters.

Waning antibody levels against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the emergence of variants of concern highlight the need for booster vaccinations. This is particularly important for the elderly population, who are at a higher risk of developing severe coronavirus disease 2019 (COVID-19) disease. While studies have shown increased antibody responses following booster vaccination, understanding the changes in T and B cell compartments induced by a third vaccine dose remains limited. We analyzed the humoral and cellular responses in subjects who received either a homologous messenger RNA(mRNA) booster vaccine (BNT162b2 + BNT162b2 + BNT162b2; ''BBB") or a heterologous mRNA booster vaccine (BNT162b2 + BNT162b2 + mRNA-1273; ''BBM") at Day 0 (prebooster), Day 7, and Day 28 (postbooster). Compared with BBB, elderly individuals (≥60 years old) who received the BBM vaccination regimen display higher levels of neutralizing antibodies against the Wuhan and Delta strains along with a higher boost in immunoglobulin G memory B cells, particularly against the Omicron variant. Circulating T helper type 1(Th1), Th2, Th17, and T follicular helper responses were also increased in elderly individuals given the BBM regimen. While mRNA vaccines increase antibody, T cell, and B cell responses against SARS-CoV-2 1 month after receiving the third dose booster, the efficacy of the booster vaccine strategies may vary depending on age group and regimen combination.

Antibody Response of Heterologous vs Homologous Messenger RNA Vaccine Boosters Against the Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant: Interim Results from the PRIBIVAC Study, a Randomized Clinical Trial.

BACKGROUND: Waning antibody levels post-vaccination and the emergence of variants of concern (VOCs) capable of evading protective immunity have raised the need for booster vaccinations. However, which combination of coronavirus disease 2019 (COVID-19) vaccines offers the strongest immune response against the Omicron variant is unknown. METHODS: This randomized, participant-blinded, controlled trial assessed the reactogenicity and immunogenicity of different COVID-19 vaccine booster combinations. A total of 100 BNT162b2-vaccinated individuals were enrolled and randomized 1:1 to either homologous (BNT162b2 + BNT162b2 + BNT162b2; "BBB") or heterologous messenger RNA (mRNA) (BNT162b2 + BNT162b2 + mRNA-1273; "BBM") booster vaccine. The primary end point was the level of neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wild-type and VOCs at day 28. RESULTS: A total of 51 participants were allocated to BBB and 49 to BBM; 50 and 48, respectively, were analyzed for safety and immunogenicity outcomes. At day 28 post-boost, mean SARS-CoV-2 spike antibody titers were lower with BBB (22 382 IU/mL; 95% confidence interval [CI], 18 210 to 27 517) vs BBM (29 751 IU/mL; 95% CI, 25 281 to 35 011; P = .034) as was the median level of neutralizing antibodies: BBB 99.0% (interquartile range [IQR], 97.9% to 99.3%) vs BBM 99.3% (IQR, 98.8% to 99.5%; P = .021). On subgroup analysis, significant higher mean spike antibody titer, median surrogate neutralizing antibody level against all VOCs, and live Omicron neutralization titer were observed only in older adults receiving BBM. Both vaccines were well tolerated. CONCLUSIONS: Heterologous mRNA-1273 booster vaccination compared with homologous BNT123b2 induced a stronger neutralizing response against the Omicron variant in older individuals. CLINICAL TRIALS REGISTRATION: NCT05142319.

Viral Dynamics and Immune Correlates of Coronavirus Disease 2019 (COVID-19) Severity.

BACKGROUND: Key knowledge gaps remain in the understanding of viral dynamics and immune response of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. METHODS: We evaluated these characteristics and established their association with clinical severity in a prospective observational cohort study of 100 patients with PCR-confirmed SARS-CoV-2 infection (mean age, 46 years; 56% male; 38% with comorbidities). Respiratory samples (n = 74) were collected for viral culture, serum samples for measurement of IgM/IgG levels (n = 30), and plasma samples for levels of inflammatory cytokines and chemokines (n = 81). Disease severity was correlated with results from viral culture, serologic testing, and immune markers. RESULTS: Fifty-seven (57%) patients developed viral pneumonia, of whom 20 (20%) required supplemental oxygen, including 12 (12%) with invasive mechanical ventilation. Viral culture from respiratory samples was positive for 19 of 74 patients (26%). No virus was isolated when the PCR cycle threshold (Ct) value was >30 or >14 days after symptom onset. Seroconversion occurred at a median (IQR) of 12.5 (9-18) days for IgM and 15.0 (12-20) days for IgG; 54/62 patients (87.1%) sampled at day 14 or later seroconverted. Severe infections were associated with earlier seroconversion and higher peak IgM and IgG levels. Levels of IP-10, HGF, IL-6, MCP-1, MIP-1α, IL-12p70, IL-18, VEGF-A, PDGF-BB, and IL-1RA significantly correlated with disease severity. CONCLUSIONS: We found virus viability was associated with lower PCR Ct value in early illness. A stronger antibody response was associated with disease severity. The overactive proinflammatory immune signatures offer targets for host-directed immunotherapy, which should be evaluated in randomized controlled trials.

Characterisation of bone and joint infections due to Group B Streptococcus serotype III sequence type 283.

In 2015, an epidemic of Group B Streptococcus (GBS) serotype III sequence type 283 (ST283) disease was reported in Singapore, associated with consumption of raw freshwater fish. In this study, we further characterise the characteristics of bone and joint infections associated with ST283 GBS in adults and the differences between ST283 and non-ST283 manifestations. A retrospective study of 54 inpatients with invasive GBS disease involving bones and/or joints from 2010 to 2015 was performed. Archived isolates were identified as GBS serotype III and ST283 positive using PCR methods. Clinical data were collected from a review of clinical charts. Twenty-three cases were ST283 and 31 were non-ST283. ST283 GBS patients were more likely to be of Chinese ethnicity, have lower Charlson comorbidity scores, and have fewer overall comorbidities, including diabetes mellitus with end-organ damage, peripheral vascular disease, and previous stroke, compared to non-ST283 GBS patients. ST283 patients had more oligoarthritis, with greater involvement of the knee, shoulder, and vertebrae, compared to monoarticular joint involvement in non-ST283 patients. Six patients had a unique combination of knee and shoulder joint involvement. All ST283 cases were mono-microbial, compared to a significant proportion of polymicrobial cultures in non-ST283 patients. Non-ST283 patients had a significantly longer length of stay and were more likely to undergo amputation or wound debridement. This study adds to growing evidence of a distinct clinical presentation associated with ST283 GBS, involving predominantly healthier patients without significant comorbidities, and with distinct clinical manifestations with regard to bone and joint disease.

Follow-up blood cultures do not reduce mortality in hospitalized patients with Gram-negative bloodstream infection: a retrospective population-wide cohort study.

OBJECTIVES: The utility of follow-up blood cultures (FUBCs) in patients with Gram-negative bloodstream infection (GN-BSI) is controversial. Observational studies have suggested significant mortality benefit but may be limited by single-centre designs, immortal time bias, and residual confounding. We examined the impact of FUBCs on mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario, Canada. METHODS: Adult patients with GN-BSI hospitalized between April 2017 and December 2021 were included. Primary outcome was all-cause mortality within 30 days. FUBC was treated as a time-varying exposure. Secondary outcomes were 90-day mortality, length of stay, and number of days alive and out of hospital at 30 and 90 days. RESULTS: Thirty-four thousand one hundred patients were included; 8807 (25.8%) patients received FUBC, of which 966 (11.0%) were positive. Median proportion of patients receiving FUBC was 18.8% (interquartile range, 10.0-29.7%; range, 0-66.1%) across 101 hospitals; this correlated with positivity and contamination rate. Eight hundred ninety (10.1%) patients in the FUBC group and 2263 (8.9%) patients in the no FUBC group died within 30 days. In the fully adjusted model, there was no association between FUBC and mortality (hazard ratio, 0.97; 95% CI, 0.90-1.04). Patients with FUBC had significantly longer length of stay (median, 11 vs. 7 days; adjusted risk ratio, 1.18; 95% CI, 1.16-1.21) and fewer number of days alive and out of hospital at 30 and 90 days. DISCUSSION: FUBC collection in patients with GN-BSI varies widely across hospitals and may be associated with prolonged hospitalization without clear survival benefit. Residual confounding may be present given the observational design. Clear benefit should be demonstrated in a randomized trial before widespread adoption of routine FUBC.

Evaluating the impact of a SIMPlified LaYered consent process on recruitment of potential participants to the Staphylococcus aureus Network Adaptive Platform trial: study protocol for a multicentre pragmatic nested randomised clinical trial (SIMPLY-SNAP trial).

INTRODUCTION: Informed consent forms (ICFs) for randomised clinical trials (RCTs) can be onerous and lengthy. The process has the potential to overwhelm patients with information, leading them to miss elements of the study that are critical for an informed decision. Specifically, overly long and complicated ICFs have the potential to increase barriers to trial participation for patients with mild cognitive impairment, those who do not speak English as a first language or among those with lower medical literacy. In turn, this can influence trial recruitment, completion and external validity. METHODS AND ANALYSIS: SIMPLY-SNAP is a pragmatic, multicentre, open-label, two-arm parallel-group superiority RCT, nested within a larger trial, the Staphylococcus aureus Network Adaptive Platform (SNAP) trial. We will randomise potentially eligible participants of the SNAP trial 1:1 to a full-length ICF or a SIMPlified LaYered (SIMPLY) consent process where basic information is summarised with embedded hyperlinks to supplemental information and videos. The primary outcome is recruitment into the SNAP trial. Secondary outcomes include patient understanding of the clinical trial, patient and research staff satisfaction with the consent process, and time taken for consent. As an exploratory outcome, we will also compare measures of diversity (eg, gender, ethnicity), according to the consent process randomised to. The planned sample size will be 346 participants. ETHICS AND DISSEMINATION: The study has been approved by the ethics review board (Sunnybrook Health Sciences Research Ethics Board) at sites in Ontario. We will disseminate study results via the SNAP trial group and other collaborating clinical trial networks. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT06168474; www. CLINICALTRIALS: gov).

Immunogenicity of mRNA vs. BBV152 vaccine boosters against Omicron subvariants: Final results from Phase B of the PRIBIVAC study, a randomized clinical trial.

BACKGROUND: BBV152 (Covaxin™) is a whole-virion inactivated SARS-CoV-2 vaccine mixed with an immune adjuvant. We aimed to compare immune responses after booster vaccination with heterologous BBV152 versus homologous mRNA vaccine. METHODS: We conducted a randomized, participant-blinded, controlled trial. Fifty mRNA-vaccinated participants were enrolled and randomized to receive an mRNA booster (n = 26) or BBV152 (n = 24). Blood samples were collected pre-vaccination, and at Day 7, 28, 180 and 360 post-booster for analysis of humoral and cellular immune responses. Primary end point was the SARS-CoV-2 anti-spike antibody titer at day 28. RESULTS: Recruitment began in January 2022 and was terminated early due to the BBV152 group meeting pre-specified criteria for futility. At Day 28 post-boost, mean SARS-CoV-2 spike antibody titers were lower with BBV152 (2004 IU/mL; 95 % confidence interval [CI], 1132-3548) vs mRNA (26,669 IU/mL; 95 % CI, 21,330-33,266; p < 0.0001), but comparable levels of spike-specific CD4 and cytotoxic T-cells were observed. Anti-spike antibody titers remained significantly different at Day 180: BBV152 4467 IU/mL (95 % CI, 1959-10,186) vs mRNA 20,749 IU/mL (95 % CI, 12,303-35,075; p = 0.0017). Levels of surrogate virus neutralizing antibodies against ancestral and Omicron subvariants BA.1 and BA.2 were significantly higher among mRNA recipients at Day 180, including after adjusting for intercurrent infection. By Day 360, anti-spike antibody titers and neutralizing antibody levels against Omicron subvariants became similar between vaccine groups. By the end of the study, 16 in each arm (mRNA 64 % and BBV152 69.6 %) had breakthrough infections and time to COVID-19 infection between vaccine groups were similar (p = 0.63). CONCLUSIONS: Wild-type SARS-CoV-2 anti-spike antibody titer and surrogate virus neutralizing test levels against wild-type SARS-CoV-2 and Omicron subvariants BA.1/BA.2/BA.5 were significantly higher at Day 28 and 180 in individuals who received booster vaccination with an mRNA vaccine compared with BBV152. CLINICAL TRIAL REGISTRATION NUMBER: NCT05142319.

First SARS-CoV-2 Omicron infection as an effective immune booster among mRNA vaccinated individuals: final results from the first phase of the PRIBIVAC randomised clinical trial.

BACKGROUND: Understanding how SARS-CoV-2 breakthrough infections impacts the breadth of immune responses against existing and pre-emergent SARS-CoV-2 strains is needed to develop an evidence-based long-term immunisation strategy. METHODS: We performed a randomised, controlled trial to assess the immunogenicity of homologous (BNT162b2) versus heterologous (mRNA-1273) booster vaccination in 100 BNT162b2-vaccinated infection-naïve individuals enrolled from October 2021. Post hoc analysis was performed to assess the impact of SARS-CoV-2 infection on humoral and cellular immune responses against wild-type SARS-CoV-2 and/or Omicron subvariants. FINDINGS: 93 participants completed the study at day 360. 71% (66/93) of participants reported first SARS-CoV-2 Omicron infection by the end of the study with similar proportions of infections between homologous and heterologous booster groups (72.3% [34/47] vs 69.6% [32/46]; p = 0.82). Mean wildtype SARS-CoV-2 anti-S-RBD antibody level was significantly higher in heterologous booster group compared with homologous group at day 180 (14,588 IU/mL; 95% CI, 10,186-20,893 vs 7447 IU/mL; 4646-11,912; p = 0.025). Participants who experienced breakthrough infections during the Omicron BA.1/2 wave had significantly higher anti-S-RBD antibody levels against wildtype SARS-CoV-2 and antibody neutralisation against BA.1 and pre-emergent BA.5 compared with infection-naïve participants. Regardless of hybrid immunity status, wildtype SARS-CoV-2 anti-S-RBD antibody level declined significantly after six months post-booster or post-SARS-CoV-2 infection. INTERPRETATION: Booster vaccination with mRNA-1273 was associated with significantly higher antibody levels compared with BNT162b2. Antibody responses are narrower and decline faster among uninfected, vaccinated individuals. Boosters may be more effective if administered shortly before infection outbreaks and at least six months after last infection or booster. FUNDING: Singapore NMRC, USFDA, MRC.

Are we enrolling the right patients? A scoping review of external validity and generalizability of clinical trials in bloodstream infections.

BACKGROUND: Having a representative population in randomized clinical trials (RCTs) improves external validity and generalizability of trial results. There are limited data examining differences between RCT-enrolled and real-world populations in bloodstream infections (BSI). OBJECTIVES: We conducted a scoping review aiming to review studies assessing generalizability of BSI RCT populations, to identify sub-groups that have been systematically under-represented and to explore approaches to improve external validity of future RCTs. SOURCES: MEDLINE, Embase, and Cochrane Library databases were searched for terms related to external validity or generalizability, BSI, and clinical trials in papers published up to 1 August 2023. Studies comparing enrolled versus nonenrolled patients, or papers discussing external validity or generalizability in the context of BSI RCTs were included. CONTENT: Sixteen papers were included in the final review. Five compared RCT-enrolled and nonenrolled participants from the same source population. There were significant differences between the two groups in all studies, with nonenrolled patients having a greater comorbidity burden and consistently worse outcomes including mortality. We identified several barriers to improving generalizability of RCT populations and outlined potential approaches to reduce these barriers, such as alternative/simplified consent processes, streamlining eligibility criteria and follow-up procedures, quota-based sampling techniques, and ensuring diversity in site and study team selection. IMPLICATIONS: Study cohorts in BSI RCTs are not representative of the general BSI patient population. As we increasingly adopt large pragmatic trials in infectious diseases, it is important to recognize the importance of maximizing generalizability to ensure that our research findings are of direct relevance to our patients.

Evaluating the use of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in the workup of Staphylococcus aureus bacteraemia: a cost-utility analysis.

OBJECTIVES: The use of positron emission tomography/computed tomography (PET/CT) in the evaluation of patients with Staphylococcus aureus bacteraemia can improve the diagnosis of infectious foci and guide clinical management. We aimed to evaluate the cost-utility of PET/CT among adults hospitalized with Staphylococcus aureus bacteraemia. METHODS: A cost-utility analysis was conducted from the healthcare payer perspective using a probabilistic Markov cohort model assessing three diagnostic strategies: (a) PET/CT in all patients, (b) PET/CT in high-risk patients only, and (c) routine diagnostic workup. Primary outcomes were quality-adjusted life years (QALYs), costs in Canadian dollars, and an incremental cost-effectiveness ratio. Deterministic and probabilistic sensitivity analyses were conducted to evaluate parameter uncertainty. RESULTS: Routine workup resulted in an average of 16.64 QALYs from the time of diagnosis at a lifetime cost of $209 060/patient. This was dominated by PET/CT in high-risk patients (i.e. greater effectiveness at lower costs) with average 16.88 QALYs at a cost of $199 552. Compared with PET/CT in high-risk patients only, PET/CT for all patients cost on average $11 960 more but resulted in 0.14 more QALYs, giving an incremental cost-effectiveness ratio of $83 500 (cost per additional QALY gained); however, there was a high degree of uncertainty comparing these two strategies. At a willingness-to-pay threshold of $50 000/QALY, PET/CT in high-risk patients was the most cost-effective strategy in 58.6% of simulations vs. 37.9% for PET/CT in all patients. DISCUSSION: Our findings suggest that a strategy of using PET/CT in high-risk patients is more cost-effective than no PET/CT. Randomized controlled trials should be conducted to evaluate the use of PET/CT in different patient groups.

Unlocking the DOOR-how to design, apply, analyse, and interpret desirability of outcome ranking endpoints in infectious diseases clinical trials.

BACKGROUND: Desirability of outcome ranking (DOOR) outcomes, with or without response adjusted for antibiotic risk (RADAR), are increasingly used in infectious diseases randomized clinical trials (RCTs), with the advantage of being able to combine multiple clinical outcomes and antibiotic duration in a single metric. However, it remains poorly understood, and there is considerable heterogeneity in its use. OBJECTIVES: In this scoping review, we explain how to design, use and analyse a DOOR endpoint, and highlight several pitfalls and potential improvements that can be made to DOOR/RADAR. SOURCES: The Ovid MEDLINE database was searched for terms related to DOOR in English-language articles published up to 31 December 2022. Articles discussing DOOR methodology and/or reporting clinical trial analyses (as either primary, secondary, or post-hoc analysis) using a DOOR outcome were included. CONTENT: Seventeen articles were included in the final review, of which nine reported DOOR analyses of 12 RCTs. Eight articles discussed DOOR methodology. We synthesised information from these articles and discuss (a) how to develop a DOOR scale, (b) how to conduct a DOOR/RADAR analysis, (c) use in clinical trials, (d) use of alternative tiebreakers apart from RADAR, (e) partial credit analyses, and (f) criticisms and pitfalls of DOOR/RADAR. IMPLICATIONS: DOOR is an important innovation for RCTs in infectious diseases. We highlight potential areas of methodological improvement for future research. There remains considerable heterogeneity in its implementation, and further collaborative efforts, with a more diverse range of perspectives, should be made to develop consensus scales for use in prospective studies.

Real-World Use of Sotrovimab for Pre-Emptive Treatment in High-Risk Hospitalized COVID-19 Patients: An Observational Cross-Sectional Study.

Data on use of monoclonal antibodies (mAbs) in hospitalized patients are limited. In this cross-sectional study, we evaluated the use of mAbs for early treatment of unvaccinated hospitalized patients with mild-to-moderate COVID-19. All inpatients at our center were screened on 27 October 2021. Primary outcome was in-hospital deterioration as defined by a composite of oxygen requirement, intensive care unit (ICU) admission, or mortality within 28 days of admission. Ninety-four out of 410 COVID-19 inpatients were included in the final analysis, of whom 19 (20.2%) received early treatment with sotrovimab. The median age was 73 years (IQR 61-83), and 35 (37.2%) were female. Although the treatment group was significantly older and had more comorbidities, there was a lower proportion of progression to oxygen requirement (31.6% vs. 54.7%), ICU admission (10.5% vs. 24.0%), or mortality (5.3% vs. 13.3%). Kaplan-Meier curves showed a significant difference in time to in-hospital deterioration (log-rank test, p = 0.043). Cox proportional hazards model for in-hospital deterioration showed that sotrovimab treatment was protective (hazard ratio, 0.41; 95% CI, 0.17-0.99; p = 0.047) after adjustment for baseline ISARIC deterioration score. Our findings support the use of sotrovimab for early treatment in hospitalized patients with mild-to-moderate COVID-19 at a high risk of disease progression.

Antibiotic Therapy in the Treatment of COVID-19 Pneumonia: Who and When?

BACKGROUND: COVID-19 imposes challenges in antibiotic decision-making due to similarities between bacterial pneumonia and moderate to severe COVID-19. We evaluated the effects of antibiotic therapy on the clinical outcomes of COVID-19 pneumonia patients and diagnostic accuracy of key inflammatory markers to inform antibiotic decision-making. METHODS: An observational cohort study was conducted in patients hospitalised with COVID-19 at the National Centre for Infectious Diseases and Tan Tock Seng Hospital, Singapore, from January to April 2020. Patients were defined as receiving empiric antibiotic treatment for COVID-19 if started within 3 days of diagnosis. RESULTS: Of 717 patients included, 86 (12.0%) were treated with antibiotics and 26 (3.6%) had documented bacterial infections. Among 278 patients with COVID-19 pneumonia, those treated with antibiotics had more diarrhoea (26, 34.7% vs. 24, 11.8%, p < 0.01), while subsequent admissions to the intensive care unit were not lower (6, 8.0% vs. 10, 4.9% p = 0.384). Antibiotic treatment was not independently associated with lower 30-day (adjusted odds ratio, aOR 19.528, 95% confidence interval, CI 1.039-367.021) or in-hospital mortality (aOR 3.870, 95% CI 0.433-34.625) rates after adjusting for age, co-morbidities and severity of COVID-19 illness. Compared to white cell count and procalcitonin level, the C-reactive protein level had the best diagnostic accuracy for documented bacterial infections (area under the curve, AUC of 0.822). However, the sensitivity and specificity were less than 90%. CONCLUSION: Empiric antibiotic use in those presenting with COVID-19 pneumonia did not prevent deterioration or mortality. More studies are needed to evaluate strategies to diagnose bacterial co-infections in these patients.

Evaluation of the safety and immunogenicity of different COVID-19 vaccine combinations in healthy individuals: study protocol for a randomized, subject-blinded, controlled phase 3 trial [PRIBIVAC].

BACKGROUND: Over 2021, COVID-19 vaccination programs worldwide focused on raising population immunity through the primary COVID-19 vaccine series. In Singapore, two mRNA vaccines (BNT162b2 and mRNA-1273) and the inactivated vaccine CoronaVac are currently authorized under the National Vaccination Programme for use as the primary vaccination series. More than 90% of the Singapore population has received at least one dose of a COVID-19 vaccine as of December 2021. With the demonstration that vaccine effectiveness wanes in the months after vaccination, and the emergence of Omicron which evades host immunity from prior infection and/or vaccination, attention in many countries has shifted to how best to maintain immunity through booster vaccinations. METHODS: The objectives of this phase 3, randomized, subject-blinded, controlled clinical trial are to assess the safety and immunogenicity of heterologous boost COVID-19 vaccine regimens (intervention groups 1-4) compared with a homologous boost regimen (control arm) in up to 600 adult volunteers. As non-mRNA vaccine candidates may enter the study at different time points depending on vaccine availability and local regulatory approval, participants will be randomized at equal probability to the available intervention arms at the time of randomization. Eligible participants will have received two doses of a homologous mRNA vaccine series with BNT162b2 or mRNA-1273 at least 6 months prior to enrolment. Participants will be excluded if they have a history of confirmed SARS or SARS-CoV-2 infection, are immunocompromised, or are pregnant. Participants will be monitored for adverse events and serious adverse events by physical examinations, laboratory tests and self-reporting. Blood samples will be collected at serial time points [pre-vaccination/screening (day - 14 to day 0), day 7, day 28, day 180, day 360 post-vaccination] for assessment of antibody and cellular immune parameters. Primary endpoint is the level of anti-SARS-CoV-2 spike immunoglobulins at day 28 post-booster and will be measured against wildtype SARS-CoV-2 and variants of concern. Comprehensive immune profiling of the humoral and cellular immune response to vaccination will be performed. DISCUSSION: This study will provide necessary data to understand the quantity, quality, and persistence of the immune response to a homologous and heterologous third booster dose of COVID-19 vaccines. This is an important step in developing COVID-19 vaccination programs beyond the primary series. TRIAL REGISTRATION: ClinicalTrials.gov NCT05142319 . Registered on 2 Dec 2021.

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.

The Pandemic Academy: Reflections of Infectious Diseases Fellows During COVID-19.

The COVID-19 pandemic has taken over the world at an unprecedented scale. As Infectious Diseases fellows, this has come straight into the heart of our specialty and created a unique impact on our training progress and perspective. Here, we reflect on our early experiences during the first three months of battling COVID-19 in Singapore and glean some lessons for this pandemic and beyond.