History of cerebrovascular disease but not dementia increases the risk for secondary vascular events during SARS-CoV-2 infection with presumed Omicron variant: a retrospective observational study.

BACKGROUND AND PURPOSE: This study aimed to investigate if pre-existing neurological conditions, such as dementia and a history of cerebrovascular disease, increase the risk of severe outcomes including death, intensive care unit (ICU) admission and vascular events in patients hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in 2022, when Omicron was the predominant variant. METHODS: A retrospective analysis was conducted of all patients with SARS-CoV-2 infection, confirmed by polymerase chain reaction test, admitted to the University Medical Center Hamburg-Eppendorf from 20 December 2021 until 15 August 2022. In all, 1249 patients were included in the study. In-hospital mortality was 3.8% and the ICU admission rate was 9.9%. Ninety-three patients with chronic cerebrovascular disease and 36 patients with pre-existing all-cause dementia were identified and propensity score matching by age, sex, comorbidities, vaccination status and dexamethasone treatment was performed in a 1:4 ratio with patients without the respective precondition using nearest neighbor matching. RESULTS: Analysis revealed that neither pre-existing cerebrovascular disease nor all-cause dementia increased mortality or the risk for ICU admission. All-cause dementia in the medical history also had no effect on vascular complications under investigation. In contrast, an increased odds ratio for both pulmonary artery embolism and secondary cerebrovascular events was observed in patients with pre-existing chronic cerebrovascular disease and myocardial infarction in the medical history. CONCLUSION: These findings suggest that patients with pre-existing cerebrovascular disease and myocardial infarction in their medical history may be particularly susceptible to vascular complications following SARS-CoV-2 infection with presumed Omicron variant.

Absence of self-reported neuropsychiatric and somatic symptoms after Omicron variant SARS-CoV-2 breakthrough infections.

Persistent somatic and neuropsychiatric symptoms have been frequently described in patients after infection with severe acute respiratory syndrome coronavirus 2 even after a benign clinical course of the acute infection during the early phases of the coronavirus severe acute respiratory syndrome coronavirus 2 pandemic and are part of Long COVID. The Omicron variant emerged in November 2021 and has rapidly become predominant due to its high infectivity and suboptimal vaccine cross-protection. The frequency of neuropsychiatric post-acute sequelae after infection with the severe acute respiratory syndrome coronavirus 2 Omicron and adequate vaccination status is not known. Here, we aimed to characterize post-acute symptoms in individuals with asymptomatic or mildly symptomatic breakthrough infection with severe acute respiratory syndrome coronavirus 2. These individuals had either proven infection with the Omicron variant (n = 157) or their infection occurred in 2022 where Omicron was the predominant variant of severe acute respiratory syndrome coronavirus 2 in Germany (n = 107). This monocentric cross-sectional study was conducted at the University Medical Center Hamburg-Eppendorf between 11 February 2022 and 11 April 2022. We employed questionnaires addressing self-reported somatic symptom burden (Somatic Symptom Scale 8) and neuropsychiatric symptoms including mood (Patient Health Questionnaire 2), anxiety (Generalized Anxiety Disorder 7), attention (Mindful Attention Awareness Scale) and fatigue (Fatigue Assessment Scale) in a cohort of hospital workers. Scores were compared between 175 individuals less than 4 weeks after positive testing for severe acute respiratory syndrome coronavirus 2, 88 individuals more than 4 weeks after positive testing and 87 severe acute respiratory syndrome coronavirus 2 uninfected controls. The majority (n = 313; 89.5%) of included individuals were vaccinated at least three times. After recovery from infection, no significant differences in scores assessing neuropsychiatric and somatic symptoms were detected between the three groups (severe acute respiratory syndrome coronavirus 2 uninfected controls, individuals less and more than 4 weeks after positive testing) independent of age, sex, preconditions and vaccination status. In addition, self-reported symptom burden did not significantly correlate with the number of vaccinations against severe acute respiratory syndrome coronavirus 2, time from recovery or the number of infections. Notably, in all three groups, the mean scores for each item of our questionnaire lay below the pathological threshold. Our data show that persistent neuropsychiatric and somatic symptoms after recovery from severe acute respiratory syndrome coronavirus 2 infection in fully vaccinated hospital workers do not occur more frequently than that in uninfected individuals. This will guide healthcare professionals in the clinical management of patients after recovery from breakthrough infections with severe acute respiratory syndrome coronavirus 2.

Longitudinal SARS-CoV-2 Seroprevalence among Employees in Outpatient Care Services in Hamburg.

The risk of SARS-CoV-2 infection is particularly high for healthcare workers during the pandemic. Home care workers visit many different households per shift. Encounters with mostly elderly patients and their relatives increase the potential for the undetected spread of SARS-CoV-2. In order to gain insight into the seroprevalence of SARS-CoV-2 antibodies and possible transmission risks in outpatient care, this follow-up study was conducted with nursing services in Hamburg. The aim was to estimate the dynamics of seroprevalence in this occupational group over a 12-month period, to identify occupation-specific risk factors, and to collect information on the vaccination status of the surveyed nursing staff. Antibody testing for SARS-CoV-2 IgG against the S1 domain (EUROIMUN Analyser I® Lübeck, Germany) was performed on participating healthcare workers with patient contact at a total of four time points within one year from July 2020 to October 2021 (baseline, follow-up after three, six and twelve months). The data were mostly analysed descriptively. Differences in IgG titres were analysed using variance analysis methods, particularly Tukey's range test. The seroprevalence was 1.2% (8/678) at baseline and 1.5% (9/581) at the three-month follow-up (T1). At the second follow-up (T2) after six months, vaccination against SARS-CoV-2 was available from January 2021 onwards. The prevalence rate of positive IgG antibodies relative to the S1 domain of the spike protein test among unvaccinated individuals was 6.5%. At (T3) after twelve months (July to October 2021), 482 participants were enrolled, and 85.7% of the workers were considered fully vaccinated at this time point, while 51 individuals were unvaccinated. The prevalence was 13.7% (7/51). In our study, a low seroprevalence was found among home care workers, which was lower than in our studies conducted in the clinical setting. Therefore, it can be assumed that the occupational risk of infection is rather low for both the nursing staff and the patients/clients cared for in the outpatient setting. The good provision of protective equipment and the high vaccination rate of the staff probably had a positive influence.

Sotrovimab in Hospitalized Patients with SARS-CoV-2 Omicron Variant Infection: a Propensity Score-Matched Retrospective Cohort Study.

In vitro data suggest the monoclonal antibody sotrovimab may have lost inhibitory capability against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant. We aimed to provide real-life data on clinical outcomes in hospitalized patients. We retrospectively analyzed patients who were treated at the University Medical Center Hamburg-Eppendorf, Germany, between December 2021 and June 2022. Out of all 1,254 patients, 185 were treated with sotrovimab: 147 patients received sotrovimab monotherapy, and 38 received combination treatment with sotrovimab and remdesivir. We compared in-hospital mortality for the different treatment regimens for patients treated on regular wards and the intensive care unit separately and performed propensity score matching by age, sex, comorbidities, immunosuppression, and additional dexamethasone treatment to select patients who did not receive antiviral treatment for comparison. No difference in in-hospital mortality was observed between any of the treatment groups and the respective control groups. These findings underline that sotrovimab adds no clinical benefit for hospitalized patients with SARS-CoV-2 Omicron variant infections. IMPORTANCE This study shows that among hospitalized patients with SARS-CoV-2 Omicron variant infection at risk of disease progression, treatment with sotrovimab alone or in combination with remdesivir did not decrease in-hospital mortality. These real-world clinical findings in combination with previous in vitro data about lacking neutralizing activity of sotrovimab against SARS-CoV-2 Omicron variant do not support sotrovimab as a treatment option in these patients.

Analysis of the humoral and cellular response after the third COVID-19 vaccination in patients with autoimmune hepatitis.

BACKGROUND & AIMS: To explore the humoral and T-cell response to the third COVID-19 vaccination in autoimmune hepatitis (AIH). METHODS: Anti-SARS-CoV-2 antibody titers were prospectively determined in 81 AIH patients and 53 healthy age- and sex-matched controls >7 days (median 35) after the first COVID-19 booster vaccination. The spike-specific T-cell response was assessed using an activation-induced marker assay (AIM) in a subset of patients. RESULTS: Median antibody levels were significantly lower in AIH compared to controls (10 908 vs. 25 000 AU/ml, p < .001), especially in AIH patients treated with MMF (N = 14, 4542 AU/ml, p = .004) or steroids (N = 27, 7326 AU/ml, p = .020). Also, 48% of AIH patients had antibody titers below the 10% percentile of the healthy controls (9194 AU/ml, p < .001). AIH patients had a high risk of failing to develop a spike-specific T-cell response (15/34 (44%) vs. 2/16 (12%), p = .05) and showed overall lower frequencies of spike-specific CD4 + T cells (median: 0.074% vs 0.283; p = .01) after the booster vaccination compared to healthy individuals. In 34/81 patients, antibody titers before and after booster vaccination were available. In this subgroup, all patients but especially those without detectable/low antibodies titers (<100 AU/ml) after the second vaccination (N = 11/34) showed a strong, 148-fold increase. CONCLUSION: A third COVID-19 vaccination efficiently boosts antibody levels and T-cell responses in AIH patients and even seroconversion in patients with the absent immune response after two vaccinations, but to a lower level compared to controls. Therefore, we suggest routinely assessing antibody levels in AIH patients and offering additional booster vaccinations to those with suboptimal responses.

Risk factors for worsening of somatic symptom burden in a prospective cohort during the COVID-19 pandemic.

Introduction: Little is known about risk factors for both Long COVID and somatic symptoms that develop in individuals without a history of COVID-19 in response to the pandemic. There is reason to assume an interplay between pathophysiological mechanisms and psychosocial factors in the etiology of symptom persistence. Objective: Therefore, this study investigates specific risk factors for somatic symptom deterioration in a cohort of German adults with and without prior SARS-CoV-2 infection. Methods: German healthcare professionals underwent SARS-CoV-2 IgG antibody testing and completed self-rating questionnaires at baseline and 21 months later between April 2020 and February 2022. Differences in variables between the time points were analyzed and a regression analysis was performed to predict somatic symptom deterioration at follow-up. Results: Seven hundred fifty-one adults completed both assessments. Until follow-up, n = 58 had contracted SARS-CoV-2 confirmed by serology. Between baseline and follow-up, signs of mental and physical strain increased significantly in the sample. Symptom expectations associated with COVID-19 and a self-reported history of COVID-19, but not serologically confirmed SARS-CoV-2 infection, significantly predicted somatic symptom deterioration at follow-up. A further predictor was baseline psychological symptom burden. Conclusions: This study supports a disease-overarching biopsychosocial model for the development of burdensome somatic symptoms during the COVID-19 pandemic and supports research findings that symptom burden may be more related to the psychosocial effects of the pandemic than to infection itself. Future studies on Long COVID should include SARS-CoV-2 negative control groups and consider symptom burden prior to infection in order to avoid an overestimation of prevalence rates.

[Seasonal Influenza - Update on Epidemiology, Prevention and Therapy]. / Saisonale Influenza ­ Aktuelles zu Epidemiologie, Prävention und Therapie.

Infection control measures and travel restrictions implemented during the COVID-19 pandemic have limited the transmission of seasonal influenza viruses as well. It must be assumed that after these public health measures have largely been lifted, influenza activity will sharply increase in the coming influenza season. Anticipating the potentially high number of cases, the co-circulation of influenza viruses and SARS-CoV-2, efforts to increase vaccination rates against both infectious diseases must be given more attention.

High-resolution analysis of individual spike peptide-specific CD4+ T-cell responses in vaccine recipients and COVID-19 patients.

Objectives: Potential differences in the breadth, distribution and magnitude of CD4+ T-cell responses directed against the SARS-CoV-2 spike glycoprotein between vaccinees, COVID-19 patients and subjects who experienced both ways of immunisation have not been comprehensively compared on a peptide level. Methods: Following virus-specific in vitro cultivation, we determined the T-cell responses directed against 253 individual overlapping 15-mer peptides covering the entire SARS-CoV-2 spike glycoprotein using IFN-γ ELISpot and intracellular cytokine staining. In vitro HLA binding was determined for selected peptides. Results: We mapped 955 single peptide-specific CD4+ T-cell responses in a cohort of COVID-19 patients (n = 8), uninfected vaccinees (n = 16) and individuals who experienced both infection and vaccination (n = 11). Patients and vaccinees (two-time and three-time vaccinees alike) had a comparable number of CD4+ T-cell responses (median 26 vs. 29, P = 0.7289). Most of these specificities were conserved in B.1.1.529 and the BA.4 and BA.5 sublineages. The highest magnitude of these in vitro IFN-γ CD4+ T-cell responses was observed in COVID-19 patients (median 0.35%), and three-time vaccinees showed a higher magnitude than two-time vaccinees (median 0.091% vs. 0.175%, P < 0.0001). Twelve peptide specificities were each detected in at least 40% of subjects. In vitro HLA binding showed promiscuous presentation by DRB1 molecules for several peptides. Conclusion: Both SARS-CoV-2 infection and vaccination prime broadly directed T-cell responses directed against the SARS-CoV-2 spike glycoprotein. This comprehensive high-resolution analysis of spike peptide specificities will be a useful resource for further investigation of spike-specific T-cell responses.

Three Separate Spike Antigen Exposures by COVID-19 Vaccination or SARS-CoV-2 Infection Elicit Strong Humoral Immune Responses in Healthcare Workers.

BACKGROUND: The immunogenicity of different COVID-19 vaccine regimens and combinations in naïve and convalescent individuals has not been formally tested in controlled studies, and real-life observational studies are scarce. METHODS: We assessed the SARS-CoV-2 infection and COVID-19 vaccination-induced immunity of 697 hospital workers at the University Medical Center Hamburg-Eppendorf between 17 and 31 January 2022. RESULTS: The overall prevalence of anti-NC-SARS-CoV-2 antibodies indicating prior infection was 9.8% (n = 68) and thus lower than the seroprevalence in the general population. All vaccinated individuals had detectable anti-S1-RBD-SARS-CoV-2 antibodies (median AU/mL [IQR]: 13,891 [8505-23,543]), indicating strong protection against severe COVID-19. Individuals who received three COVID-19 vaccine doses (median AU/mL [IQR]: 13,856 [8635-22,705]) and those who resolved a prior SARS-CoV-2 infection and had received two COVID-19 vaccine doses (median AU/mL [IQR] 13,409 [6934-25,000]) exhibited the strongest humoral immune responses. CONCLUSIONS: The current study indicates that three exposures to the viral spike protein by either SARS-CoV-2 infection or COVID-19 vaccination are necessary to elicit particularly strong humoral immune responses, which supports current vaccination recommendations.

Clinical efficacy and in vitro neutralization capacity of monoclonal antibodies for severe acute respiratory syndrome coronavirus 2 delta and omicron variants.

We aimed to provide in vitro data on the neutralization capacity of different monoclonal antibody (mAb) preparations against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta and omicron variant, respectively, and describe the in vivo RNA kinetics of coronavirus disease 2019 (COVID-19) patients treated with the respective mAbs. Virus neutralization assays were performed to assess the neutralizing effect of the mAb formulations casirivimab/imdevimab and sotrovimab on the SARS-CoV-2 delta and omicron variant. Additionally, respiratory tract SARS-CoV-2 RNA kinetics are provided for 25 COVID-19 patients infected with either delta variant (n = 18) or omicron variant (n = 7) treated with the respective mAb formulations during their hospital stay. In the virus neutralization assay, sotrovimab exhibits neutralizing capacity at therapeutically achievable concentrations against the SARS-CoV-2 delta and omicron variant. In contrast, casivirimab/imdevimab had neutralizing capacity against the delta variant but failed neutralization against the omicron variant except for a very high concentration above the currently recommended therapeutic dosage. In patients with delta variant infections treated with casivirimab/imdevimab, we observed a rapid decrease of respiratory viral RNA at day 3 after mAb therapy. In contrast, no such prompt decline was observed in patients with delta variant or omicron variant infections receiving sotrovimab.

[Attitudes Towards COVID-19 Vaccination Compared to Influenza Vaccination Among Hospital Staff]. / Einstellungen gegenüber der COVID-19-Impfung im Vergleich zur Grippeschutzimpfung bei Krankenhauspersonal.

This cross-sectional study compared hospital staff who had received influenza or COVID-19 vaccination or who had refused COVID-19 vaccination in terms of attitudes towards each vaccination, uptake of influenza vaccination and reasons for refusing COVID-19 vaccination. COVID-19 vaccine refusers rated the risk of infection for themselves and in general and the effectiveness of the vaccination lowest and the vaccination risk highest compared to the other two groups. They also reported the lowest past uptake of influenza vaccination. Perceived pressure to vaccinate proved to be a relevant barrier. Future vaccination campaigns should maintain a balance between information on vaccines, the need for vaccination, and voluntary uptake.

Correction: Broadly directed SARS-CoV-2-specific CD4+ T cell response includes frequently detected peptide specificities within the membrane and nucleoprotein in patients with acute and resolved COVID-19.

[This corrects the article DOI: 10.1371/journal.ppat.1009842.].

Lymphocytopenia and Anti-CD38 Directed Treatment Impact the Serological SARS-CoV-2 Response after Prime Boost Vaccination in Patients with Multiple Myeloma.

Even though several SARS-CoV-2 vaccines have shown high effectiveness in the prevention of COVID-19 in healthy subjects, vaccination response in patients with plasma-cell-related disorders (PCD) remains widely unknown. Here, we report on an analysis describing the serological response after prime-boost SARS-CoV-2 vaccination in PCD patients, as compared to a healthy control group, and on possible influencing factors of serological responses. Blood samples were analyzed for the presence of quantitative anti-SARS-CoV-2 spike RBD Ig. A total of 82 patients were included; 67 received mRNA-, eight vector-based and four heterologous vaccinations. SARS-CoV-2 antibody titers (SP-AbT) were assessed in a mean of 23 days (SD ± 11 days) after the first and in a mean 21 days (SD ± 9) after prime-boost vaccination. A positive SP-AbT was detected in 31.9% of PCD patients after the first vaccination, and in 88.9% (44/49) after prime-boost vaccination, which was significantly less likely than that in the control group (100%, 78/78) (p = 0.008). Furthermore, we have been able to validate our previously suggested threshold of 30 CD19+ B lymphocytes/µL as being predictive for SP-AbT development. Despite anti-CD38 directed therapy, quadruplet treatment, higher age and missing deep remission, which correlated negatively with SP-AbT appearance, SP-AbT formation is possible in a majority of myeloma patients after prime-boost vaccination.

Low SARS-CoV-2 infection rates and high vaccine-induced immunity among German healthcare workers at the end of the third wave of the COVID-19 pandemic.

In this longitudinal cohort study, we assessed the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) seroconversion rates and analyzed the coronavirus disease 2019 (COVID-19) vaccine-induced immunity of 872 hospital workers at the University Medical Center Hamburg-Eppendorf between May 11 and May 31, 2021. The overall seroprevalence of anti-NC-SARS-CoV-2 antibodies was 4.7% (n = 41), indicating low SARS-CoV-2 infection rates and persistent effectiveness of hospital-wide infection control interventions during the second and third wave of the pandemic. In total, 92.7% (n = 808) out of the entire study cohort, 98.2% (n = 325) of those who had been vaccinated once and all 393 individuals who had been vaccinated twice had detectable anti-S1-RBD-SARS-CoV-2 antibody titers and no significant differences in vaccine-induced immune response were detected between male and female individuals and between different age groups. Vaccinated study participants with detectable anti-NC-SARS-CoV-2 antibody titers (n = 30) developed generally higher anti-S1-RBD-SARS-CoV-2 antibody titers compared to anti-NC-SARS-CoV-2 negative individuals (n = 694) (median titer: 7812 vs. 345 BAU/ml, p < 0.0001). Furthermore, study participants who received heterologous vaccination with AZD1222 followed by an mRNA vaccine showed markedly higher anti-S1-RBD-SARS-CoV-2 antibody titers than individuals who received two doses of an mRNA vaccine or two doses of AZD1222 (median titer: AZD1222/AZD1222: 1069 BAU/ml, mRNA/mRNA: 1388 BAU/ml, AZD1222/mRNA: 9450 BAU/ml; p < 0.0001). Our results indicate that infection control interventions were generally effective in preventing nosocomial transmission of SARS-CoV-2 and that COVID-19 vaccines can elicit strong humoral responses in the majority of a real-world cohort of hospital workers.

Broadly directed SARS-CoV-2-specific CD4+ T cell response includes frequently detected peptide specificities within the membrane and nucleoprotein in patients with acute and resolved COVID-19.

The aim of this study was to define the breadth and specificity of dominant SARS-CoV-2-specific T cell epitopes using a comprehensive set of 135 overlapping 15-mer peptides covering the SARS-CoV-2 envelope (E), membrane (M) and nucleoprotein (N) in a cohort of 34 individuals with acute (n = 10) and resolved (n = 24) COVID-19. Following short-term virus-specific in vitro cultivation, the single peptide-specific CD4+ T cell response of each patient was screened using enzyme linked immuno spot assay (ELISpot) and confirmed by single-peptide intracellular cytokine staining (ICS) for interferon-γ (IFN-γ) production. 97% (n = 33) of patients elicited one or more N, M or E-specific CD4+ T cell responses and each patient targeted on average 21.7 (range 0-79) peptide specificities. Overall, we identified 10 N, M or E-specific peptides that showed a response frequency of more than 36% and five of them showed high binding affinity to multiple HLA class II binders in subsequent in vitro HLA binding assays. Three peptides elicited CD4+ T cell responses in more than 55% of all patients, namely Mem_P30 (aa146-160), Mem_P36 (aa176-190), both located within the M protein, and Ncl_P18 (aa86-100) located within the N protein. These peptides were further defined in terms of length and HLA restriction. Based on this epitope and restriction data we developed a novel DRB*11 tetramer (Mem_aa145-164) and examined the ex vivo phenotype of SARS-CoV-2-specific CD4+ T cells in one patient. This detailed characterization of single T cell peptide responses demonstrates that SARS-CoV-2 infection universally primes a broad T cell response directed against multiple specificities located within the N, M and E structural protein.

[Mild COVID-19 disease in healthcare workers at a German university clinic : The "first wave" at the University Medical Center Hamburg-Eppendorf]. / Milde COVID-19-Verläufe bei Mitarbeitenden einer Universitätsklinik : Die "erste Welle" am Universitätsklinikum Hamburg-Eppendorf.

BACKGROUND: Healthcare workers are among the most exposed and potentially most threatened populations of the ongoing COVID-19 pandemic. Despite some reports on numbers of infections with SARS-CoV­2 in German healthcare workers, the courses of their clinical presentation when affected by COVID-19 are not well described. OBJECTIVE: In this contribution, characteristics and progressions of infected cases among healthcare workers at the University Medical Center Hamburg-Eppendorf during the first wave of the COVID-19 pandemic will be presented. METHODS: Between 1 July and 28 July 2020, 67 healthcare workers, who previously tested positive for SARS-CoV­2 via PCR, were invited via E­mail to participate in an anonymous online questionnaire; 39 persons participated. RESULTS: Participants (58%) were mostly ≤ 39 years old (64%) and female (70%). Most healthcare workers were involved in direct patient management (85%), including contact with SARS-CoV­2 positive patients (62%). All participants reported acute symptoms with a median duration of 19 days. The most frequent symptoms were fatigue (85%), anosmia (67%), cough (64%), headache (62%), and shortness of breath (51%). The disease course was mostly mild with low admission rates (5%). Ongoing symptoms lasting more than four weeks post-symptom-onset, particularly anosmia, fatigue, and shortness of breath, were reported by 38%. This group more frequently had pre-existing conditions (53% vs. 12%, p = 0.010), specifically hypertension (27% vs. 4%, p = 0.062). DISCUSSION: Healthcare workers reported mostly mild courses of COVID-19 despite increased contact with SARS-CoV-2 patients. However, some reported persistent symptoms months after infection.

Patient Characteristics and Clinical Course of COVID-19 Patients Treated at a German Tertiary Center during the First and Second Waves in the Year 2020.

In this study, we directly compared coronavirus disease 2019 (COVID-19) patients hospitalized during the first (27 February-28 July 2020) and second (29 July-31 December 2020) wave of the pandemic at a large tertiary center in northern Germany. Patients who presented during the first (n = 174) and second (n = 331) wave did not differ in age (median [IQR], 59 years [46, 71] vs. 58 years [42, 73]; p = 0.82) or age-adjusted Charlson Comorbidity Index (median [IQR], 2 [1, 4] vs. 2 [0, 4]; p = 0.50). During the second wave, a higher proportion of patients were treated as outpatients (11% [n = 20] vs. 20% [n = 67]), fewer patients were admitted to the intensive care unit (43% [n = 75] vs. 29% [n = 96]), and duration of hospitalization was significantly shorter (median days [IQR], 14 [8, 34] vs. 11 [5, 19]; p < 0.001). However, in-hospital mortality was high throughout the pandemic and did not differ between the two periods (16% [n = 27] vs. 16% [n = 54]; p = 0.89). While novel treatment strategies and increased knowledge about the clinical management of COVID-19 may have resulted in a less severe disease course in some patients, in-hospital mortality remained unaltered at a high level. These findings highlight the unabated need for efforts to hamper severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) transmission, to increase vaccination coverage, and to develop novel treatment strategies to prevent mortality and decrease morbidity.

Comparison of clinical characteristics and disease outcome of COVID-19 and seasonal influenza.

While several studies have described the clinical course of patients with coronavirus disease 2019 (COVID-19), direct comparisons with patients with seasonal influenza are scarce. We compared 166 patients with COVID-19 diagnosed between February 27 and June 14, 2020, and 255 patients with seasonal influenza diagnosed during the 2017-18 season at the same hospital to describe common features and differences in clinical characteristics and course of disease. Patients with COVID-19 were younger (median age [IQR], 59 [45-71] vs 66 [52-77]; P < 0001) and had fewer comorbidities at baseline with a lower mean overall age-adjusted Charlson Comorbidity Index (mean [SD], 3.0 [2.6] vs 4.0 [2.7]; P < 0.001) than patients with seasonal influenza. COVID-19 patients had a longer duration of hospitalization (mean [SD], 25.9 days [26.6 days] vs 17.2 days [21.0 days]; P = 0.002), a more frequent need for oxygen therapy (101 [60.8%] vs 103 [40.4%]; P < 0.001) and invasive ventilation (52 [31.3%] vs 32 [12.5%]; P < 0.001) and were more frequently admitted to the intensive care unit (70 [42.2%] vs 51 [20.0%]; P < 0.001) than seasonal influenza patients. Among immunocompromised patients, those in the COVID-19 group had a higher hospital mortality compared to those in the seasonal influenza group (13 [33.3%] vs 8 [11.6%], P = 0.01). In conclusion, we show that COVID-19 patients were younger and had fewer baseline comorbidities than seasonal influenza patients but were at increased risk for severe illness. The high mortality observed in immunocompromised COVID-19 patients emphasizes the importance of protecting these patient groups from SARS-CoV-2 infection.