COVID-19 vaccine effectiveness against symptomatic infection and hospitalisation in Belgium, July 2021 to May 2022.

BackgroundThe Belgian COVID-19 vaccination campaign aimed to reduce disease spread and severity.AimWe estimated SARS-CoV-2 variant-specific vaccine effectiveness against symptomatic infection (VEi) and hospitalisation (VEh), given time since vaccination and prior infection.MethodsNationwide healthcare records from July 2021 to May 2022 on testing and vaccination were combined with a clinical hospital survey. We used a test-negative design and proportional hazard regression to estimate VEi and VEh, controlling for prior infection, time since vaccination, age, sex, residence and calendar week of sampling.ResultsWe included 1,932,546 symptomatic individuals, of whom 734,115 tested positive. VEi against Delta waned from an initial estimate of 80% (95% confidence interval (CI): 80-81) to 55% (95% CI: 54-55) 100-150 days after the primary vaccination course. Booster vaccination increased initial VEi to 85% (95% CI: 84-85). Against Omicron, an initial VEi of 33% (95% CI: 30-36) waned to 17% (95% CI: 15-18), while booster vaccination increased VEi to 50% (95% CI: 49-50), which waned to 20% (95% CI: 19-21) 100-150 days after vaccination. Initial VEh for booster vaccination decreased from 96% (95% CI: 95-96) against Delta to 87% (95% CI: 86-89) against Omicron. VEh against Omicron waned to 73% (95% CI: 71-75) 100-150 days after booster vaccination. While recent prior infections conferred higher protection, infections occurring before 2021 remained associated with significant risk reduction against symptomatic infection. Vaccination and prior infection outperformed vaccination or prior infection only.ConclusionWe report waning and a significant decrease in VEi and VEh from Delta to Omicron-dominant periods. Booster vaccination and prior infection attenuated these effects.

Evaluating methodological approaches to assess the severity of infection with SARS-CoV-2 variants: scoping review and applications on Belgian COVID-19 data.

BACKGROUND: Differences in the genetic material of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants may result in altered virulence characteristics. Assessing the disease severity caused by newly emerging variants is essential to estimate their impact on public health. However, causally inferring the intrinsic severity of infection with variants using observational data is a challenging process on which guidance is still limited. We describe potential limitations and biases that researchers are confronted with and evaluate different methodological approaches to study the severity of infection with SARS-CoV-2 variants. METHODS: We reviewed the literature to identify limitations and potential biases in methods used to study the severity of infection with a particular variant. The impact of different methodological choices is illustrated by using real-world data of Belgian hospitalized COVID-19 patients. RESULTS: We observed different ways of defining coronavirus disease 2019 (COVID-19) disease severity (e.g., admission to the hospital or intensive care unit versus the occurrence of severe complications or death) and exposure to a variant (e.g., linkage of the sequencing or genotyping result with the patient data through a unique identifier versus categorization of patients based on time periods). Different potential selection biases (e.g., overcontrol bias, endogenous selection bias, sample truncation bias) and factors fluctuating over time (e.g., medical expertise and therapeutic strategies, vaccination coverage and natural immunity, pressure on the healthcare system, affected population groups) according to the successive waves of COVID-19, dominated by different variants, were identified. Using data of Belgian hospitalized COVID-19 patients, we were able to document (i) the robustness of the analyses when using different variant exposure ascertainment methods, (ii) indications of the presence of selection bias and (iii) how important confounding variables are fluctuating over time. CONCLUSIONS: When estimating the unbiased marginal effect of SARS-CoV-2 variants on the severity of infection, different strategies can be used and different assumptions can be made, potentially leading to different conclusions. We propose four best practices to identify and reduce potential bias introduced by the study design, the data analysis approach, and the features of the underlying surveillance strategies and data infrastructure.

Invasive pulmonary aspergillosis in solid-organ transplant patients in the intensive care unit.

INTRODUCTION: Solid-organ transplantation (SOT) is a well-known risk factor for invasive pulmonary aspergillosis (IPA). We report on the epidemiology and outcome of SOT patients with IPA in an intensive care unit (ICU) setting. METHODS: This is a secondary study based on a subset of SOT patients from a prospective observational multicenter cohort (the AspICU project) including ICU patients with at least one Aspergillus spp. positive culture. Cases were classified as proven, probable, or putative IPA, or as Aspergillus-colonized. Mortality was reported at 12 weeks. RESULTS: The study included 52 SOT patients (of which 18 lung, 17 liver, 12 kidney, and five heart transplants). Sixteen patients had proven IPA, 28 were categorized as putative IPA (of which only five reached a probable IPA diagnosis according to the European Organization for Research and Treatment of Cancer/Mycosis Study Group and Research Consortium criteria), and eight as Aspergillus-colonization. Among patients with IPA, 20 (45.5%) developed IPA during their ICU stay following transplantation whereas 24 patients (54.5%) had a medical ICU admission. Regarding medical imaging, nearly all IPA cases presented with non-specific findings as only nine demonstrated robust findings suggestive for invasive fungal disease. Overall, severity of the disease was reflected by a high prevalence of underlying conditions and acute organ derangements. Mortality among patients with IPA was 68%. Lung transplantation was associated with better survival (50%). CONCLUSION: IPA in SOT patients in the ICU develops in the presence of overall high severity of the disease. It rarely presents with suggestive medical imaging thereby hampering diagnosis. IPA in ICU patients with SOT carries a grim prognosis.

Prevention of Ventilator-Associated and Early Postoperative Pneumonia Through Tapered Endotracheal Tube Cuffs: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

OBJECTIVE: Microaspiration of subglottic secretions is considered a major pathogenic mechanism of hospital-acquired pneumonia, either early postoperative or ventilator-associated pneumonia. Tapered endotracheal tube cuffs have been proposed to provide a better seal of the extraluminal airway, thereby preventing microaspiration and possibly hospital-acquired pneumonia. We performed a systematic review and meta-analysis to assess the value of endotracheal tubes with tapered cuffs in the prevention of hospital-acquired pneumonia. DATA SOURCES: A systematic search of MEDLINE, EMBASE, CENTRAL/CCTR, ClinicalTrials.gov, and ICTRP was conducted up to March 2017. STUDY SELECTION: Eligible trials were randomized controlled clinical trials comparing the impact of tapered cuffs versus standard cuffs on hospital-acquired pneumonia. DATA EXTRACTION: Random-effects meta-analysis calculated odds ratio and 95% CI for hospital-acquired pneumonia occurrence rate between groups. Secondary outcome measures included mortality, duration of mechanical ventilation, length of hospital and ICU stay, and cuff underinflation. DATA SYNTHESIS: Six randomized controlled clinical trials with 1,324 patients from intensive care and postoperative wards were included. Only two studies concomitantly applied subglottic secretion drainage, and no trial performed continuous cuff pressure monitoring. No significant difference in hospital-acquired pneumonia incidence per patient was found when tapered cuffs were compared with standard cuffs (odds ratio, 0.97; 95% CI, [0.73-1.28]; p = 0.81). There were likewise no differences in secondary outcomes. CONCLUSIONS: Application of tapered endotracheal tube cuffs did not reduce hospital-acquired pneumonia incidence among ICU and postoperative patients. Further research should examine the impact of concomitant use of tapered cuffs with continuous cuff pressure monitoring and subglottic secretion drainage.

Prevention of hospital-acquired bloodstream infections through chlorhexidine gluconate-impregnated washcloth bathing in intensive care units: a systematic review and meta-analysis of randomised crossover trials.

We assessed the impact of 2% daily patient bathing with chlorhexidine gluconate (CHG) washcloths on the incidence of hospital-acquired (HA) and central line-associated (CLA) bloodstream infections (BSI) in intensive care units (ICUs). We searched randomised studies in Medline, EMBASE, Cochrane Library (CENTRAL) and Web of Science databases up to April 2015. Primary outcomes were total HABSI, central line, and non-central line-associated BSI rates per patient-days. Secondary outcomes included Gram-negative and Gram-positive BSI rates and adverse events. Four randomised crossover trials involved 25 ICUs and 22,850 patients. Meta-analysis identified a total HABSI rate reduction (odds ratio (OR): 0.74; 95% confidence interval (CI): 0.60-0.90; p = 0.002) with moderate heterogeneity (I2 = 36%). Subgroup analysis identified significantly stronger rate reductions (p = 0.01) for CLABSI (OR: 0.50; 95% CI: 0.35-0.71; p < 0.001) than other HABSI (OR: 0.82; 95% CI: 0.70-0.97; p = 0.02) with low heterogeneity (I2 = 0%). This effect was evident in the Gram-positive subgroup (OR: 0.55; 95% CI: 0.31-0.99; p = 0.05), but became non-significant after removal of a high-risk-of-bias study. Sensitivity analysis revealed that the intervention effect remained significant for total and central line-associated HABSI. We suggest that use of CHG washcloths prevents HABSI and CLABSI in ICUs, possibly due to the reduction in Gram-positive skin commensals.

Prevention of central line-associated bloodstream infections through quality improvement interventions: a systematic review and meta-analysis.

This systematic review and meta-analysis examines the impact of quality improvement interventions on central line-associated bloodstream infections in adult intensive care units. Studies were identified through Medline and manual searches (1995-June 2012). Random-effects meta-analysis obtained pooled odds ratios (ORs) and 95% confidence intervals (CIs). Meta-regression assessed the impact of bundle/checklist interventions and high baseline rates on intervention effect. Forty-one before-after studies identified an infection rate decrease (OR, 0.39 [95% CI, .33-.46]; P < .001). This effect was more pronounced for trials implementing a bundle or checklist approach (P = .03). Furthermore, meta-analysis of 6 interrupted time series studies revealed an infection rate reduction 3 months postintervention (OR, 0.30 [95% CI, .10-.88]; P = .03). There was no difference in infection rates between studies with low or high baseline rates (P = .18). These results suggest that quality improvement interventions contribute to the prevention of central line-associated bloodstream infections. Implementation of care bundles and checklists appears to yield stronger risk reductions.

Epidemiology and risk factors for mortality in critically ill patients with pancreatic infection.

Background: The AbSeS-classification defines specific phenotypes of patients with intra-abdominal infection based on the (1) setting of infection onset (community-acquired, early onset, or late-onset hospital-acquired), (2) presence or absence of either localized or diffuse peritonitis, and (3) severity of disease expression (infection, sepsis, or septic shock). This classification system demonstrated reliable risk stratification in intensive care unit (ICU) patients with intra-abdominal infection. This study aimed to describe the epidemiology of ICU patients with pancreatic infection and assess the relationship between the components of the AbSeS-classification and mortality. Methods: This was a secondary analysis of an international observational study ("AbSeS") investigating ICU patients with intra-abdominal infection. Only patients with pancreatic infection were included in this analysis (n=165). Mortality was defined as ICU mortality within 28 days of observation for patients discharged earlier from the ICU. Relationships with mortality were assessed using logistic regression analysis and reported as odds ratio (OR) and 95% confidence interval (CI). Results: The overall mortality was 35.2% (n=58). The independent risk factors for mortality included older age (OR=1.03, 95% CI: 1.0 to 1.1 P=0.023), localized peritonitis (OR=4.4, 95% CI: 1.4 to 13.9 P=0.011), and persistent signs of inflammation at day 7 (OR=9.5, 95% CI: 3.8 to 23.9, P<0.001) or after the implementation of additional source control interventions within the first week (OR=4.0, 95% CI: 1.3 to 12.2, P=0.013). Gram-negative bacteria were most frequently isolated (n=58, 49.2%) without clinically relevant differences in microbial etiology between survivors and non-survivors. Conclusions: In pancreatic infection, a challenging source/damage control and ongoing pancreatic inflammation appear to be the strongest contributors to an unfavorable short-term outcome. In this limited series, essentials of the AbSeS-classification, such as the setting of infection onset, diffuse peritonitis, and severity of disease expression, were not associated with an increased mortality risk.ClinicalTrials.gov number: NCT03270345.

A Belgian student with black eschars.

BACKGROUND: Human cowpox virus infection is a rare zoonotic disease. Cowpox virus is a member of the Orthopoxvirus genus, like smallpox. Over the last years records of cowpox virus transmission from pet cats and pet rats to humans in Europe have increased. This observation may result from the loss of cross-immunity against orthopoxviruses after discontinuation of routine smallpox vaccination in the 1980s. CASE PRESENTATION: We report the first case of a human cowpox infection in an unvaccinated Belgian citizen. This 19-year-old student presented with multiple necrotic skin lesions on the chin, the scalp and the pubic region, and with cervical lymphadenopathy and flu-like symptoms. The diagnosis of human cowpox was based on electron microscopic findings and PCR examination performed on a skin biopsy of the pubic lesion. Close contact with cats (her domestic cats or cats from a local shelter) was probably the source of transmission. Spreading of the lesions was likely the result of autoinoculation. After six months all lesions spontaneously healed with atrophic scars. DISCUSSION: To enhance awareness of this rare viral zoonosis and to verify the suspected increase in incidence and symptom severity after cessation of smallpox vaccination, one could argue whether human cowpox should become a notifiable disease.

Homologous and Heterologous Prime-Boost Vaccination: Impact on Clinical Severity of SARS-CoV-2 Omicron Infection among Hospitalized COVID-19 Patients in Belgium.

We investigated effectiveness of (1) mRNA booster vaccination versus primary vaccination only and (2) heterologous (viral vector-mRNA) versus homologous (mRNA-mRNA) prime-boost vaccination against severe outcomes of BA.1, BA.2, BA.4 or BA.5 Omicron infection (confirmed by whole genome sequencing) among hospitalized COVID-19 patients using observational data from national COVID-19 registries. In addition, it was investigated whether the difference between the heterologous and homologous prime-boost vaccination was homogenous across Omicron sub-lineages. Regression standardization (parametric g-formula) was used to estimate counterfactual risks for severe COVID-19 (combination of severity indicators), intensive care unit (ICU) admission, and in-hospital mortality under exposure to different vaccination schedules. The estimated risk for severe COVID-19 and in-hospital mortality was significantly lower with an mRNA booster vaccination as compared to only a primary vaccination schedule (RR = 0.59 [0.33; 0.85] and RR = 0.47 [0.15; 0.79], respectively). No significance difference was observed in the estimated risk for severe COVID-19, ICU admission and in-hospital mortality with a heterologous compared to a homologous prime-boost vaccination schedule, and this difference was not significantly modified by the Omicron sub-lineage. Our results support evidence that mRNA booster vaccination reduced the risk of severe COVID-19 disease during the Omicron-predominant period.

Sociodemographic and socioeconomic disparities in COVID-19 vaccine uptake in Belgium: a nationwide record linkage study.

BACKGROUND: Recent studies have identified important social inequalities in SARS-CoV-2 infections and related COVID-19 outcomes in the Belgian population. The aim of our study was to investigate the sociodemographic and socioeconomic characteristics associated with the uptake of COVID-19 vaccine in Belgium. METHODS: We conducted a cross-sectional analysis of the uptake of a first COVID-19 vaccine dose among 5 342 110 adults (≥18 years) in Belgium on 31 August 2021. We integrated data from four national data sources: the Belgian vaccine register (vaccination status), COVID-19 Healthdata (laboratory test results), DEMOBEL (sociodemographic/socioeconomic data) and the Common Base Register for HealthCare Actors (individuals licensed to practice a healthcare profession in Belgium). We used multivariable logistic regression analysis for identifying characteristics associated with not having obtained a first COVID-19 vaccine dose in Belgium and for each of its three regions (Flanders, Brussels and Wallonia). RESULTS: During the study period, 10% (536 716/5 342 110) of the Belgian adult population included in our study sample was not vaccinated with a first COVID-19 vaccine dose. A lower COVID-19 vaccine uptake was found among young individuals, men, migrants, single parents, one-person households and disadvantaged socioeconomic groups (with lower levels of income and education, unemployed). Overall, the sociodemographic and socioeconomic disparities were comparable for all regions. CONCLUSIONS: The identification of sociodemographic and socioeconomic disparities in COVID-19 vaccination uptake is critical to develop strategies guaranteeing a more equitable vaccination coverage of the Belgian adult population.

Mobile phones as a vector for Healthcare-Associated Infection: A systematic review.

INTRODUCTION: Mobile phones have become indispensable accessories of both our social and professional lives. They increase the quality of healthcare by providing fast communication, and easy access to laboratory results, imaging and patients' files. Simultaneously however, they may act as vectors for potentially pathogenic micro-organisms and as such hold a potential risk for nosocomial infection. OBJECTIVES: To assess the risk of mobile phones as vectors for nosocomial infection and the impact of disinfecting mobile phones on infection risks. METHODS: The MEDLINE and Embase database were searched from January 2000 - January 2019 for a systematic review according to PRISMA guidelines. Eligible studies of any design were critically appraised by two independent reviewers. RESULTS: We identified 50 studies, of which 12 were interventional. Data for a total of 5425 microbiological samples resulted in a prevalence of potentially pathogenic micro-organisms from 0% to 100%. The 2 most commonly found micro-organisms were coagulase-negative staphylococci (most commonly found in 30 studies) and Staphylococcus aureus (most commonly found in 10 studies). The frequency of microbial growth varied across studies. CONCLUSIONS: The use of mobile phones by healthcare workers without proper disinfection may imply a risk for nosocomial infection. A direct relationship however, remains unproven. Healthcare workers are recommended to include proper handling of mobile phones in their 'classic' hand hygiene routine as proposed by the World Health Organisation.

Gram-negative central line-associated bloodstream infection incidence peak during the summer: a national seasonality cohort study.

Central line-associated bloodstream infections (CLABSI) cause increased morbidity, mortality, and hospital costs that are partially preventable. The phenomenon of seasonality among CLABSI rates has not been fully elucidated, but has implications for accurate surveillance and infection prevention trials. Longitudinal dynamic cohort of hospitals participating in hospital-wide and intensive care unit bloodstream infection surveillance for at least one full year over 2000 to 2014. Mixed-effects negative binomial regression analysis calculated the peak-to-low ratio between months as an adjusted CLABSI incidence rate ratio (IRR) with 95% confidence intervals (CI). Multivariate regression models examined the associations between CLABSI pathogens and ambient temperature and relative humidity. The study population included 104 hospital sites comprising 11,239 CLABSI. Regression analysis identified a hospital-wide increase in total CLABSI during July-August, with a higher gram-negative peak-to-low incidence rate ratio (IRR 2.52 [95% CI 1.92-3.30], p < 0.001) compared to gram-positive bacteria (IRR 1.29 [95% CI 1.11-1.48], p < 0.001). Subgroup analysis replicated this trend for CLABSI diagnosed in the intensive care unit. Only gram-negative CLABSI rates were associated with increased temperature (IRR + 30.3% per 5 °C increase [95% CI 17.3-43.6], p < 0.001) and humidity (IRR + 22.9% per 10% increase [95% CI 7.7-38.3), p < 0.001). The incidence and proportion of gram-negative CLABSI approximately doubled during the summer periods. Ambient temperature and humidity were associated with increases of hospital-acquired gram-negative infections. CLABSI surveillance, preventive intervention trials and epidemiological studies should consider seasonal variation and climatological factors when preparing study designs or interpreting their results.

Seasonal variation of hospital-acquired bloodstream infections: A national cohort study.

BACKGROUND: Hospital-acquired bloodstream infections (HABSIs) cause increased morbidity, mortality, and hospital costs that are partially preventable. HABSI seasonality has been described for gram-negative bacteria but has not been stratified per infection origin. OBJECTIVE: To assess seasonality among all types of HABSIs and their associations with climate. METHODS: Hospitals performing surveillance for at least 1 full calendar year between 2000 and 2014 were included. Mixed-effects negative binomial regression analysis calculated the peak-to-low monthly ratio as an adjusted HABSI incidence rate ratio (IRR) with 95% confidence intervals (CIs). Another regression model examined associations between HABSI rates and climate variables. These analyses were stratified by microorganism and infectious origin. RESULTS: The study population included 104 hospitals comprising 44,111 HABSIs. Regression analysis identified an incidence rate ratio (IRR) peak in August for gram-negative HABSIs (IRR, 1.59; 95% CI, 1.49-1.71), CLABSIs (IRR, 1.49; 95% CI, 1.30-1.70), and urinary tract HABSI (IRR, 1.52; 95% CI, 1.34-1.74). The gram-negative incidence increased by 13.1% (95% CI, 9.9%-16.4%) for every 5°C increase in temperature. Seasonality was most present among E. coli, K. pneumoniae, E. cloacae, and the nonfermenters. Gram-positive and pulmonary HABSIs did not demonstrate seasonal variation. CONCLUSIONS: Seasonality with summer spikes occurred among gram-negative bacteria, CLABSIs, and urinary tract HABSIs. Higher ambient temperature was associated with gram-negative HABSI rates. The preventable causative factors for seasonality, such as the nurse-to-patient ratio, indoor room temperature or device-utilization, need to be examined to assess areas for improving patient safety.

Severity of infection with the SARS-CoV-2 B.1.1.7 lineage among hospitalized COVID-19 patients in Belgium.

INTRODUCTION: The pathogenesis of COVID-19 depends on the interplay between host characteristics, viral characteristics and contextual factors. Here, we compare COVID-19 disease severity between hospitalized patients in Belgium infected with the SARS-CoV-2 variant B.1.1.7 and those infected with previously circulating strains. METHODS: The study is conducted within a causal framework to study the severity of SARS-CoV-2 variants by merging surveillance registries in Belgium. Infection with SARS-CoV-2 B.1.1.7 ('exposed') was compared to infection with previously circulating strains ('unexposed') in terms of the manifestation of severe COVID-19, intensive care unit (ICU) admission, or in-hospital mortality. The exposed and unexposed group were matched based on the hospital and the mean ICU occupancy rate during the patient's hospital stay. Other variables identified as confounders in a Directed Acyclic Graph (DAG) were adjusted for using regression analysis. Sensitivity analyses were performed to assess the influence of selection bias, vaccination rollout, and unmeasured confounding. RESULTS: We observed no difference between the exposed and unexposed group in severe COVID-19 disease or in-hospital mortality (RR = 1.15, 95% CI [0.93-1.38] and RR = 0.92, 95% CI [0.62-1.23], respectively). The estimated standardized risk to be admitted in ICU was significantly higher (RR = 1.36, 95% CI [1.03-1.68]) when infected with the B.1.1.7 variant. An age-stratified analysis showed that among the younger age group (≤65 years), the SARS-CoV-2 variant B.1.1.7 was significantly associated with both severe COVID-19 progression and ICU admission. CONCLUSION: This matched observational cohort study did not find an overall increased risk of severe COVID-19 or death associated with B.1.1.7 infection among patients already hospitalized. There was a significant increased risk to be transferred to ICU when infected with the B.1.1.7 variant, especially among the younger age group. However, potential selection biases advocate for more systematic sequencing of samples from hospitalized COVID-19 patients.

Clinical Severity of SARS-CoV-2 Omicron Variant Compared with Delta among Hospitalized COVID-19 Patients in Belgium during Autumn and Winter Season 2021-2022.

This retrospective multi-center matched cohort study assessed the risk for severe COVID-19 (combination of severity indicators), intensive care unit (ICU) admission, and in-hospital mortality in hospitalized patients when infected with the Omicron variant compared to when infected with the Delta variant. The study is based on a causal framework using individually-linked data from national COVID-19 registries. The study population consisted of 954 COVID-19 patients (of which, 445 were infected with Omicron) above 18 years old admitted to a Belgian hospital during the autumn and winter season 2021-2022, and with available viral genomic data. Patients were matched based on the hospital, whereas other possible confounders (demographics, comorbidities, vaccination status, socio-economic status, and ICU occupancy) were adjusted for by using a multivariable logistic regression analysis. The estimated standardized risk for severe COVID-19 and ICU admission in hospitalized patients was significantly lower (RR = 0.63; 95% CI (0.30; 0.97) and RR = 0.56; 95% CI (0.14; 0.99), respectively) when infected with the Omicron variant, whereas in-hospital mortality was not significantly different according to the SARS-CoV-2 variant (RR = 0.78, 95% CI (0.28-1.29)). This study demonstrates the added value of integrated genomic and clinical surveillance to recognize the multifactorial nature of COVID-19 pathogenesis.

Association between COVID-19 Primary Vaccination and Severe Disease Caused by SARS-CoV-2 Delta Variant among Hospitalized Patients: A Belgian Retrospective Cohort Study.

We aimed to investigate vaccine effectiveness against progression to severe COVID-19 (acute respiratory distress syndrome (ARDS), intensive care unit (ICU) admission and/or death) and in-hospital death in a cohort of hospitalized COVID-19 patients. Mixed effects logistic regression analyses were performed to estimate the association between receiving a primary COVID-19 vaccination schedule and severe outcomes after adjusting for patient, hospital, and vaccination characteristics. Additionally, the effects of the vaccine brands including mRNA vaccines mRNA-1273 and BNT162b2, and adenovirus-vector vaccines ChAdOx1 (AZ) and Ad26.COV2.S (J&J) were compared to each other. This retrospective, multicenter cohort study included 2493 COVID-19 patients hospitalized across 73 acute care hospitals in Belgium during the time period 15 August 2021-14 November 2021 when the Delta variant (B1.617.2) was predominant. Hospitalized COVID-19 patients that received a primary vaccination schedule had lower odds of progressing to severe disease (OR (95% CI); 0.48 (0.38; 0.60)) and in-hospital death (OR (95% CI); 0.49 (0.36; 0.65)) than unvaccinated patients. Among the vaccinated patients older than 75 years, mRNA vaccines and AZ seemed to confer similar protection, while one dose of J&J showed lower protection in this age category. In conclusion, a primary vaccination schedule protects against worsening of COVID-19 to severe outcomes among hospitalized patients.

Poor timing and failure of source control are risk factors for mortality in critically ill patients with secondary peritonitis.

PURPOSE: To describe data on epidemiology, microbiology, clinical characteristics and outcome of adult patients admitted in the intensive care unit (ICU) with secondary peritonitis, with special emphasis on antimicrobial therapy and source control. METHODS: Post hoc analysis of a multicenter observational study (Abdominal Sepsis Study, AbSeS) including 2621 adult ICU patients with intra-abdominal infection in 306 ICUs from 42 countries. Time-till-source control intervention was calculated as from time of diagnosis and classified into 'emergency' (< 2 h), 'urgent' (2-6 h), and 'delayed' (> 6 h). Relationships were assessed by logistic regression analysis and reported as odds ratios (OR) and 95% confidence interval (CI). RESULTS: The cohort included 1077 cases of microbiologically confirmed secondary peritonitis. Mortality was 29.7%. The rate of appropriate empiric therapy showed no difference between survivors and non-survivors (66.4% vs. 61.3%, p = 0.1). A stepwise increase in mortality was observed with increasing Sequential Organ Failure Assessment (SOFA) scores (19.6% for a value ≤ 4-55.4% for a value > 12, p < 0.001). The highest odds of death were associated with septic shock (OR 3.08 [1.42-7.00]), late-onset hospital-acquired peritonitis (OR 1.71 [1.16-2.52]) and failed source control evidenced by persistent inflammation at day 7 (OR 5.71 [3.99-8.18]). Compared with 'emergency' source control intervention (< 2 h of diagnosis), 'urgent' source control was the only modifiable covariate associated with lower odds of mortality (OR 0.50 [0.34-0.73]). CONCLUSION: 'Urgent' and successful source control was associated with improved odds of survival. Appropriateness of empirical antimicrobial treatment did not significantly affect survival suggesting that source control is more determinative for outcome.

Epidemiology and age-related mortality in critically ill patients with intra-abdominal infection or sepsis: an international cohort study.

OBJECTIVE: To describe epidemiology and age-related mortality in critically ill older adults with intra-abdominal infection. METHODS: A secondary analysis was undertaken of a prospective, multi-national, observational study (Abdominal Sepsis Study, ClinicalTrials.gov #NCT03270345) including patients with intra-abdominal infection from 309 intensive care units (ICUs) in 42 countries between January and December 2016. Mortality was considered as ICU mortality, with a minimum of 28 days of observation when patients were discharged earlier. Relationships with mortality were assessed by logistic regression analysis. RESULTS: The cohort included 2337 patients. Four age groups were defined: middle-aged patients [reference category; 40-59 years; n=659 (28.2%)], young-old patients [60-69 years; n=622 (26.6%)], middle-old patients [70-79 years; n=667 (28.5%)] and very old patients [≥80 years; n=389 (16.6%)]. Secondary peritonitis was the predominant infection (68.7%) and was equally prevalent across age groups. Mortality increased with age: 20.9% in middle-aged patients, 30.5% in young-old patients, 31.2% in middle-old patients, and 44.7% in very old patients (P<0.001). Compared with middle-aged patients, young-old age [odds ratio (OR) 1.62, 95% confidence interval (CI) 1.21-2.17], middle-old age (OR 1.80, 95% CI 1.35-2.41) and very old age (OR 3.69, 95% CI 2.66-5.12) were independently associated with mortality. Other independent risk factors for mortality included late-onset hospital-acquired intra-abdominal infection, diffuse peritonitis, sepsis/septic shock, source control failure, liver disease, congestive heart failure, diabetes and malnutrition. CONCLUSIONS: For ICU patients with intra-abdominal infection, age >60 years was associated with mortality; patients aged ≥80 years had the worst prognosis. Comorbidities and overall disease severity further compromised survival. As all of these factors are non-modifiable, it remains unclear how to improve outcomes.

Conceptual causal framework to assess the effect of SARS-CoV-2 variants on COVID-19 disease severity among hospitalized patients.

BACKGROUND: SARS-CoV-2 strains evolve continuously and accumulate mutations in their genomes over the course of the pandemic. The severity of a SARS-CoV-2 infection could partly depend on these viral genetic characteristics. Here, we present a general conceptual framework that allows to study the effect of SARS-CoV-2 variants on COVID-19 disease severity among hospitalized patients. METHODS: A causal model is defined and visualized using a Directed Acyclic Graph (DAG), in which assumptions on the relationship between (confounding) variables are made explicit. Various DAGs are presented to explore specific study design options and the risk for selection bias. Next, the data infrastructure specific to the COVID-19 surveillance in Belgium is described, along with its strengths and weaknesses for the study of clinical impact of variants. DISCUSSION: A well-established framework that provides a complete view on COVID-19 disease severity among hospitalized patients by combining information from different sources on host factors, viral factors, and healthcare-related factors, will enable to assess the clinical impact of emerging SARS-CoV-2 variants and answer questions that will be raised in the future. The framework shows the complexity related to causal research, the corresponding data requirements, and it underlines important limitations, such as unmeasured confounders or selection bias, inherent to repurposing existing routine COVID-19 data registries. TRIAL REGISTRATION: Each individual research project within the current conceptual framework will be prospectively registered in Open Science Framework (OSF identifier: https://doi.org/10.17605/OSF.IO/UEF29 ). OSF project created on 18 May 2021.

The role of organizational characteristics on the outcome of COVID-19 patients admitted to the ICU in Belgium.

BACKGROUND: Several studies have investigated the predictors of in-hospital mortality for COVID-19 patients who need to be admitted to the Intensive Care Unit (ICU). However, no data on the role of organizational issues on patients' outcome are available in this setting. The aim of this study was therefore to assess the role of surge capacity organisation on the outcome of critically ill COVID-19 patients admitted to ICUs in Belgium. METHODS: We conducted a retrospective analysis of in-hospital mortality in Belgian ICU COVID-19 patients via the national surveillance database. Non-survivors at hospital discharge were compared to survivors using multivariable mixed effects logistic regression analysis. Specific analyses including only patients with invasive ventilation were performed. To assess surge capacity, data were merged with administrative information on the type of hospital, the baseline number of recognized ICU beds, the number of supplementary beds specifically created for COVID-19 ICU care and the "ICU overflow" (i.e. a time-varying ratio between the number of occupied ICU beds by confirmed and suspected COVID-19 patients divided by the number of recognized ICU beds reserved for COVID-19 patients; ICU overflow was present when this ratio is ≥ 1.0). FINDINGS: Over a total of 13,612 hospitalised COVID-19 patients with admission and discharge forms registered in the surveillance period (March, 1 to August, 9 2020), 1903 (14.0%) required ICU admission, of whom 1747 had available outcome data. Non-survivors (n = 632, 36.1%) were older and had more frequently various comorbid diseases than survivors. In the multivariable analysis, ICU overflow, together with older age, presence of comorbidities, shorter delay between symptom onset and hospital admission, absence of hydroxychloroquine therapy and use of invasive mechanical ventilation and of ECMO, was independently associated with an increased in-hospital mortality. Similar results were found in in in the subgroup of invasively ventilated patients. In addition, the proportion of supplementary beds specifically created for COVID-19 ICU care to the previously existing total number of ICU beds was associated with increased in-hospital mortality among invasively ventilated patients. The model also indicated a significant between-hospital difference in in-hospital mortality, not explained by the available patients and hospital characteristics. INTERPRETATION: Surge capacity organisation as reflected by ICU overflow or the creation of COVID-19 specific supplementary ICU beds were found to negatively impact ICU patient outcomes. FUNDING: No funding source was available for this study.