Background: Metabolites are involved in biological process that govern the immune response to infection and vaccination. Knowledge of how metabolites interact with the immune system during immunization with the COVID-19 vaccine is limited. Here, we report that the serum metabolites are correlated with the magnitude of the antibody response in recipients receiving the inactivated COVID-19 vaccine, which provides critical information for studying metabolism regarding the human immune response to vaccination. Methods: 106 healthy volunteers without history of SARS-CoV-2 infection or vaccination were prospectively enrolled to receive the primary series of two doses of inactivated whole-virion SARS-CoV-2 vaccine. The serum samples were collected 2–4 weeks after the second dose. The magnitude of the anti-RBD antibody was quantified using surrogate virus neutralization tests. The profile of metabolites in serum was identified using untargeted metabolomics analysis. Results: The level of anti-RBD antibody 14–28 days after the second dose was significantly elevated and its interpersonal variability was diverse in a wide range. Thirty-two samples at extremes of the anti-RBD antibody titer were selected to discover the metabolic correlates. Two hundred and fifteen differential metabolites associated with antibody response independent of body mass index were identified. Pregnenolone and sphingolipid metabolism might be involved in the modulation of the human antibody response to the inactivated COVID-19 vaccine. Conclusion: We discovered key metabolites as well as those with a related functional significance that might modulate the human immune response to vaccination.

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Background Sepsis is still a major public health concern and a medical emergency due to its high morbidity and mortality. Accurate and timely etiology diagnosis is crucial for sepsis management. As an emerging rapid and sensitive pathogen detection tool, digital droplet PCR (ddPCR) has shown promising potential in rapid identification of pathogens and antimicrobial resistance genes. However, the diagnostic value and clinical impact of ddPCR tests remains to be studied in patients with suspected sepsis. PROGRESS trial is aimed to evaluate the clinical effectiveness of a novel ddPCR assay compared with standard practice. Methods PROGRESS is a multicenter, open-label, pragmatic randomized controlled trial (pRCT) set in ten hospitals, including departments of infectious disease and intensive care units. In this study, a total of 2292 patients with suspected sepsis will be randomly assigned to two arms: the ddPCR group and the control group with a ratio of 3:1. The primary outcome is the diagnostic efficacy, that is, the sensitivity and specificity of the ddPCR assay compared with the synchronous blood culture. Secondary outcomes include the mortality rates and the mean Sequential Organ Failure Assessment (SOFA) score at follow-up time points, the length of stay in the hospital, the time to directed antimicrobial therapy, duration of broad-spectrum antibiotic use, and the EQ-5D-5L score on day 90. Discussion It is the first multicenter pragmatic RCT to explore the diagnostic efficacy and clinical impact of the ddPCR assay in patients with suspected sepsis, taking advantage of both RCT’s ability to establish causality and the feasibility of pragmatic approaches in real-world studies (RWS). This trial will help us to get a comprehensive view of the assay’s capacity for precise diagnosis and treatment of sepsis. It has the potential to monitor the pathogen load change and to guide the antimicrobial therapy, making a beneficial impact on the prognosis of sepsis patients. Trial registration: ClinicalTrial.gov, NCT05190861. Registered January 13, 2022—‘Retrospectively registered’, https://clinicaltrials.gov/ct2/show/NCT05190861.

Citrobacter koseri is an opportnistic pathogen can cause a variety of diseases. Though the mortality rate of C. koseri infections is high but there is a paucity of clinical information on them. Furthermore, the genomic features of this species are poorly studied. Herein, we presented a patient with endogenous endophthalmitis secondary to septicaemia, and collected a C. koseri isolate, CKNJ, from the blood of the patient.Whole genome sequencing revealed that the CKNJ harbors no plasmid and codes for 67 putative virulence factors. Whole genome SNP-based phylogenetic analysis revealed that strain CKNJ was close to the strains with same isolation sites. Compared to the other sequenced C. koseri chromosomes, CKNJ contains several strain-variable regions, including one prophage and two large genomic islands. The sequencing of the first complete genome of a clinical strain from China should reinforce our understanding of the genomic features and pathogenicity of this invasive infectioncausing C. koseri with clinical significance.