Respiratory failure in the acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is hypothesized to be driven by an overreacting innate immune response, where the complement system is a key player. In this prospective cohort study of 39 hospitalized coronavirus disease COVID-19 patients, we describe systemic complement activation and its association with development of respiratory failure. Clinical data and biological samples were obtained at admission, days 3 to 5, and days 7 to 10. Respiratory failure was defined as PO2/FiO2 ratio of ≤40 kPa. Complement activation products covering the classical/lectin (C4d), alternative (C3bBbP) and common pathway (C3bc, C5a, and sC5b-9), the lectin pathway recognition molecule MBL, and antibody serology were analyzed by enzyme-immunoassays; viral load by PCR. Controls comprised healthy blood donors. Consistently increased systemic complement activation was observed in the majority of COVID-19 patients during hospital stay. At admission, sC5b-9 and C4d were significantly higher in patients with than without respiratory failure (P = 0.008 and P = 0.034). Logistic regression showed increasing odds of respiratory failure with sC5b-9 (odds ratio 31.9, 95% CI 1.4 to 746, P = 0.03) and need for oxygen therapy with C4d (11.7, 1.1 to 130, P = 0.045). Admission sC5b-9 and C4d correlated significantly to ferritin (r = 0.64, P < 0.001; r = 0.69, P < 0.001). C4d, sC5b-9, and C5a correlated with antiviral antibodies, but not with viral load. Systemic complement activation is associated with respiratory failure in COVID-19 patients and provides a rationale for investigating complement inhibitors in future clinical trials.

Several studies have reported an increased incidence of candidaemia and a redistribution of species, with a decrease in the number of Candida albicans isolates. In Norway, a prospective, national surveillance study of candidaemia has been ongoing since 1991. Data from the period 1991-2003 have been published previously. The aim of this study was to follow up the incidence, species distribution and antifungal susceptibility of Candida species isolates from blood cultures in the period 2004-2012, and compare them with the corresponding findings from the period 1991-2003. Blood culture isolates of Candida species from all medical microbiological laboratories in Norway were identified and susceptibility tested at the Norwegian Mycological Reference Laboratory. A total of 1724 isolates were recovered from 1653 patients in the period 2004-2012. Comparison of the two periods showed that the average incidence of candidaemia episodes per 100 000 inhabitants increased from 2.4 (1991-2003) to 3.9 (2004-2012). The increase in incidence in the latter period was significantly higher in patients aged >40 years (p 0.001), and a marked increase was observed in patients aged >60 years (p < 0.001). In conclusion, the average incidence in Norway over a period of 22 years modestly increased from 2.4 to 3.9 per 100,000 inhabitants, this being mainly accounted for by candidaemia in the elderly. The species distribution was stable, and the rate of acquired resistance was low.

The association between pulmonary sequelae and markers of disease severity, as well as pro-fibrotic mediators, were studied in 108 patients 3 months after hospital admission for COVID-19. The COPD assessment test (CAT-score), spirometry, diffusion capacity of the lungs (DLCO), and chest-CT were performed at 23 Norwegian hospitals included in the NOR-SOLIDARITY trial, an open-labelled, randomised clinical trial, investigating the efficacy of remdesivir and hydroxychloroquine (HCQ). Thirty-eight percent had a CAT-score ≥ 10. DLCO was below the lower limit of normal in 29.6%. Ground-glass opacities were present in 39.8% on chest-CT, parenchymal bands were found in 41.7%. At admission, low pO2/FiO2 ratio, ICU treatment, high viral load, and low antibody levels, were predictors of a poorer pulmonary outcome after 3 months. High levels of matrix metalloproteinase (MMP)-9 during hospitalisation and at 3 months were associated with persistent CT-findings. Except for a negative effect of remdesivir on CAT-score, we found no effect of remdesivir or HCQ on long-term pulmonary outcomes. Three months after hospital admission for COVID-19, a high prevalence of respiratory symptoms, reduced DLCO, and persistent CT-findings was observed. Low pO2/FiO2 ratio, ICU-admission, high viral load, low antibody levels, and high levels of MMP-9 were associated with a worse pulmonary outcome.

National data from Denmark, Finland, Norway and Sweden demonstrate remarkable differences in candidaemia epidemiology. Only Denmark has reported a high incidence of 10 per 100 000 inhabitants and a species shift towards increased C. glabrata candidaemias. The reasons for this development remain unclear. The aim of this study was to explore possible contributing factors for the differences in Candida epidemiology in the Nordic countries. We used public data from 2011 from Denmark, Finland, Norway and Sweden on epidemiology, demographics, health facilities, predisposing risk factors, consumption of antimicrobial drugs and fungicides in agricultural industry. Only the prevalence of haematological malignancies (P < 0.001) was significantly higher in Denmark compared to the other Nordic countries. The antibacterial drug use of metronidazole, piperacillin-tazobactam, ciprofloxacin, colistin and carbapenems, and antifungal use of fluconazole in humans (P < 0.001), were significantly higher in Denmark compared to the other Nordic countries (all P < 0.001). Our findings suggest haematological malignancy, the use of certain antibacterial drugs and azoles in humans as possible contributing factors for the differences in Candida epidemiology. However, our results should be interpreted with caution due to the lack of long-term, case-specific data. Further studies are needed.

Background: The pathogenesis of coronavirus disease 2019 (COVID-19) is still incompletely understood, but it seems to involve immune activation and immune dysregulation. Objective: We examined the parameters of activation of different leukocyte subsets in COVID-19-infected patients in relation to disease severity. Methods: We analyzed plasma levels of myeloperoxidase (a marker of neutrophil activation), soluble (s) CD25 (sCD25) and soluble T-cell immunoglobulin mucin domain-3 (sTIM-3) (markers of T-cell activation and exhaustion), and sCD14 and sCD163 (markers of monocyte/macrophage activation) in 39 COVID-19-infected patients at hospital admission and 2 additional times during the first 10 days in relation to their need for intensive care unit (ICU) treatment. Results: Our major findings were as follows: (1) severe clinical outcome (ICU treatment) was associated with high plasma levels of sTIM-3 and myeloperoxidase, suggesting activated and potentially exhausted T cells and activated neutrophils, respectively; (2) in contrast, sCD14 and sCD163 showed no association with need for ICU treatment; and (3) levels of sCD25, sTIM-3, and myeloperoxidase were inversely correlated with degree of respiratory failure, as assessed by the ratio of PaO 2 to fraction of inspired oxygen, and were positively correlated with the cardiac marker N-terminal pro-B-type natriuretic peptide. Conclusion: Our findings suggest that neutrophil activation and, in particular, activated T cells may play an important role in the pathogenesis of COVID-19 infection, suggesting that T-celltargeted treatment options and downregulation of neutrophil activation could be of importance in this disorder. (J Allergy Clin Immunol 2021;147:92-8.)