Immunogenicity of NVX-CoV2373 heterologous boost against SARS-CoV-2 variants.

As part of a multicenter study evaluating homologous and heterologous COVID-19 booster vaccines, we assessed the magnitude, breadth, and short-term durability of binding and pseudovirus-neutralizing antibody (PsVNA) responses following a single booster dose of NVX-CoV2373 in adults primed with either Ad26.COV2.S, mRNA-1273, or BNT162b2 vaccines. NVX-CoV2373 as a heterologous booster was immunogenic and associated with no safety concerns through Day 91. Fold-rises in PsVNA titers from baseline (Day 1) to Day 29 were highest for prototypic D614G variant and lowest for more recent Omicron sub-lineages BQ.1.1 and XBB.1. Peak humoral responses against all SARS-CoV-2 variants were lower in those primed with Ad26.COV2.S than with mRNA vaccines. Prior SARS CoV-2 infection was associated with substantially higher baseline PsVNA titers, which remained elevated relative to previously uninfected participants through Day 91. These data support the use of heterologous protein-based booster vaccines as an acceptable alternative to mRNA or adenoviral-based COVID-19 booster vaccines. This trial was conducted under ClinicalTrials.gov: NCT04889209.

Epidemiology of Gram-Negative Bloodstream Infections in the United States: Results From a Cohort of 24 Hospitals.

Background: To address knowledge gaps in management of Gram-negative bloodstream infection, the Antibiotic Stewardship Implementation Collaborative was established consisting of programs from 24 academic and community hospitals across the United States. Methods: A retrospective cohort study was conducted of unique adult patients with Gram-negative bloodstream infection hospitalized at participating hospitals from January to December 2019. Patient level and microbiologic data were collected via electronic medical record review with a standardized data collection form and data dictionary. Data analysis was largely descriptive. The Pearson χ2 test to compare categorical variables and the Wilcoxon rank sum test for continuous variables were used. Results: In total, 4851 bacterial isolates from 3710 eligible unique patients were included in the cohort. Most common source of infection was the urinary tract (47.9%). Source control was achieved in 84% of cases. Escherichia coli (2471, 51.0%) was the most common Gram-negative organism recovered. Antibiogram combining isolates from all participating centers with species-level susceptibilities and source specific antibiograms for isolates from urinary, respiratory, and intraabdominal source were created. Northeast sites contributed the most extended spectrum beta-lactamase (ESBL) producing organisms (73%), but West sites had the highest percentage of ESBL producers of total isolates (16%). A statistically significant difference in percentage of ESBL-producing organisms in Whites vs. non-Whites (14.6 % and 9.5 %, respectively, P<0.01) was observed. Conclusions: While the present study was conducted pre-pandemic, it highlights the need for stewardship data collaboratives to enhance our understanding of the antimicrobial resistance patterns.

Antibiotic Use and Associated Risk Factors for Antibiotic Prescribing in COVID-19 Hospitalized Patients.

BACKGROUND: Literature suggests that antibiotic prescribing in COVID-19 patients is high. Currently, there are insufficient data on what drives antibiotic prescribing practices throughout the COVID-19 pandemic. OBJECTIVE: This study sought to determine antibiotic use rates and identify risk factors for antibiotic prescribing in hospitalized patients. It was the first study to assess risk factors for receiving more than 1 course of antibiotics. METHODS: This was a retrospective, multi-center, observational study. Patients admitted from March 1, 2020, to May 31, 2020, and treated for COVID-19 were included. The primary endpoint was the rate of antibiotic use during hospitalization. Secondary endpoints included risk factors associated with antibiotic use, risk factors associated with receiving more than 1 antibiotic course, and rate of microbiologically confirmed infections. RESULTS: A total of 208 encounters (198 patients) were included in the final analysis. Eighty-three percent of patients received at least 1 course of antibiotics, despite low rates of microbiologically confirmed infection (12%). Almost one-third of patients (30%) received more than 1 course of antibiotics. Risk factors identified for both antibiotic prescribing and receiving more than 1 course of antibiotics included increased hospital length of stay (median 12 days), intensive care unit admission, and the necessity for mechanical ventilation. CONCLUSION AND RELEVANCE: There were high rates of antibiotic prescribing with low rates of microbiologically confirmed bacterial co-infection. Many patients received more than 1 course of antibiotics during hospitalization. This study highlights the importance and demand for appropriate antibiotic stewardship practices in COVID-19 patients.

Clinical Outcomes and Treatment Strategies in Patients With Non-Carbapenemase-producing Carbapenem-Resistant Versus Carbapenem-Susceptible Enterobacterales Infections.

BACKGROUND: Carbapenem-resistant Enterobacterales (CRE) are difficult to treat and can cause significant morbidity and mortality, however most data reflect carbapenemase-producing infections. OBJECTIVE: Our objective was to evaluate clinical outcomes of non-carbapenemase-producing CRE (nCP-CRE) compared with carbapenem-susceptible Enterobacterales (CSE) infections. METHODS: This was a retrospective, multicenter, observational study (January 1, 2018 to December 31, 2020). The primary outcome was clinical success at 30 days with secondary outcomes, including clinical success at 90 days, clinical success based on treatment for nCP-CRE, persistent bacteremia, intensive care unit (ICU) admission, length of stay, and rate of Clostridioides difficile or multidrug resistant infections. RESULTS: The final analysis included 211 patients: 142 (67%) with CSE and 69 (33%) with nCP-CRE infections. Prior carbapenem exposure was more common with nCP-CRE (15% vs 4%, P = 0.01). Clinical success at 30 days was similar between groups (77% vs 74%, P = 0.73). There were no differences in secondary outcomes. There was an overall low use of carbapenems (empiric 6%, definitive 7%). Most nCP-CRE infections were treated with a monotherapy carbapenem-sparing regimen (empiric 88%, definitive 90%). Limitations include the retrospective design and the high rate of urinary infections. CONCLUSION AND RELEVANCE: Our study found no difference in clinical outcomes between nCP-CRE and CSE infections. Application of this study with future studies would help in determining optimal regimens for these infections.

Rapid decline in vaccine-boosted neutralizing antibodies against SARS-CoV-2 Omicron variant.

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibits reduced susceptibility to vaccine-induced neutralizing antibodies, requiring a boost to generate protective immunity. We assess the magnitude and short-term durability of neutralizing antibodies after homologous and heterologous boosting with mRNA and Ad26.COV2.S vaccines. All prime-boost combinations substantially increase the neutralization titers to Omicron, although the boosted titers decline rapidly within 2 months from the peak response compared with boosted titers against the prototypic D614G variant. Boosted Omicron neutralization titers are substantially higher for homologous mRNA vaccine boosting, and for heterologous mRNA and Ad26.COV2.S vaccine boosting, compared with homologous Ad26.COV2.S boosting. Homologous mRNA vaccine boosting generates nearly equivalent neutralizing activity against Omicron sublineages BA.1, BA.2, and BA.3 but modestly reduced neutralizing activity against BA.2.12.1 and BA.4/BA.5 compared with BA.1. These results have implications for boosting requirements to protect against Omicron and future variants of SARS-CoV-2. This trial was conducted under ClincalTrials.gov: NCT04889209.

Homologous and Heterologous Covid-19 Booster Vaccinations.

BACKGROUND: Although the three vaccines against coronavirus disease 2019 (Covid-19) that have received emergency use authorization in the United States are highly effective, breakthrough infections are occurring. Data are needed on the serial use of homologous boosters (same as the primary vaccine) and heterologous boosters (different from the primary vaccine) in fully vaccinated recipients. METHODS: In this phase 1-2, open-label clinical trial conducted at 10 sites in the United States, adults who had completed a Covid-19 vaccine regimen at least 12 weeks earlier and had no reported history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection received a booster injection with one of three vaccines: mRNA-1273 (Moderna) at a dose of 100 µg, Ad26.COV2.S (Johnson & Johnson-Janssen) at a dose of 5×1010 virus particles, or BNT162b2 (Pfizer-BioNTech) at a dose of 30 µg. The primary end points were safety, reactogenicity, and humoral immunogenicity on trial days 15 and 29. RESULTS: Of the 458 participants who were enrolled in the trial, 154 received mRNA-1273, 150 received Ad26.COV2.S, and 153 received BNT162b2 as booster vaccines; 1 participant did not receive the assigned vaccine. Reactogenicity was similar to that reported for the primary series. More than half the recipients reported having injection-site pain, malaise, headache, or myalgia. For all combinations, antibody neutralizing titers against a SARS-CoV-2 D614G pseudovirus increased by a factor of 4 to 73, and binding titers increased by a factor of 5 to 55. Homologous boosters increased neutralizing antibody titers by a factor of 4 to 20, whereas heterologous boosters increased titers by a factor of 6 to 73. Spike-specific T-cell responses increased in all but the homologous Ad26.COV2.S-boosted subgroup. CD8+ T-cell levels were more durable in the Ad26.COV2.S-primed recipients, and heterologous boosting with the Ad26.COV2.S vaccine substantially increased spike-specific CD8+ T cells in the mRNA vaccine recipients. CONCLUSIONS: Homologous and heterologous booster vaccines had an acceptable safety profile and were immunogenic in adults who had completed a primary Covid-19 vaccine regimen at least 12 weeks earlier. (Funded by the National Institute of Allergy and Infectious Diseases; DMID 21-0012 ClinicalTrials.gov number, NCT04889209.).

Hospital Readmissions After Laboratory-Confirmed Influenza Hospitalization.

BACKGROUND: Influenza infection causes substantial morbidity and mortality. However, little is known about hospital readmissions after an influenza hospitalization. The aim of our study was to characterize frequency of hospital readmissions among patients hospitalized with laboratory-confirmed influenza. METHODS: We conducted a retrospective study using Tennessee Emerging Infections Program Influenza Surveillance data from 2006 to 2016 and the concurrent Tennessee Hospital Discharge Data System. We analyzed demographic characteristics and outcomes to better understand frequency and factors associated with hospital readmissions. RESULTS: Of the 2897 patients with a laboratory-confirmed influenza hospitalization, 409 (14%) and 1364 (47%) had at least 1 hospital readmission within 30 days and 1 year of the influenza hospitalization, respectively. Multiple readmissions occurred in 739 patients (54%). The readmission group was older, female predominant, and had more comorbidities than patients not hospitalized. Pneumonia, acute chronic obstructive pulmonary disease/asthma exacerbation, septicemia, acute respiratory failure, and acute renal failure were the most common causes for readmission at 30 days. Underlying cardiovascular disease, lung disease, kidney disease, diabetes, immunosuppression, and liver disease were associated with increased risk of readmission during the subsequent year. CONCLUSIONS: After an admission with laboratory-confirmed influenza, there is a high likelihood of readmission within 30 days and 1 year adding to the morbidity of influenza.