Characteristics and outcomes of vaccinated and nonvaccinated patients hospitalized in a single Italian hub for COVID-19 during the Delta and Omicron waves in Northern Italy

Vaccine effectiveness against COVID-19 related hospital admission in the Netherlands by medical risk condition: A test-negative case-control study

INTRODUCTION

Vaccination remains crucial in reducing COVID-19 hospitalizations and mitigating the strain on healthcare systems. We conducted a multicenter study to assess vaccine effectiveness (VE) of primary and booster vaccination against hospitalization and to identify subgroups with reduced VE.

METHODS

From March to July 2021 and October 2021 to January 2022, a test-negative case-control study was conducted in nine Dutch hospitals. The study included adults eligible for COVID-19 vaccination who were hospitalized with respiratory symptoms. Cases tested positive for SARS-CoV-2 within 14 days prior to or 48 h after admission, while controls tested negative. Logistic regression was used to calculate VE, adjusting for calendar week, sex, age, nursing home residency and comorbidity. We explored COVID-19 case characteristics and whether there are subgroups with less effective protection by vaccination against COVID-19 hospitalization.

RESULTS

Between October 2021 to January 2022, when the Delta variant was dominant, 335 cases and 277 controls were included. VE of primary and booster vaccination was 78 % (95 % CI: 65-86), and 89 % (95 % CI: 69-96), respectively. Using data from both study periods, including 700 cases and 511 controls, VE of primary vaccination was significantly reduced in those aged 60+ and patients with malignancy, chronic cardiac disease or an immunocompromising condition.

CONCLUSION

Although VE against hospitalization was 78% and increased to 89% after boosting during the Delta-dominant study period, VE was lower in certain high risk groups, for which indirect protection or other protective measures might be of added importance.

Clinical features and 28-day mortality predictors of vaccinated patients admitted to a COVID-19 ICU hub in Italy

BACKGROUND

COVID-19 vaccination has been proved to be effective in preventing hospitalization and illness progression, even though data on mortality of vaccinated patients in the intensive care unit (ICU) are conflicting. The aim of this study was to investigate the characteristics of vaccinated patients admitted to ICU according to their immunization cycle and to outline the risk factors for 28-day mortality. This observational study included adult patients admitted to ICU for acute respiratory failure (ARF) due to SARS-CoV-2 and who had received at least one dose of vaccine.

RESULTS

Fully vaccination was defined as a complete primary cycle from < 120 days or a booster dose from > 14 days. All the other patients were named partially vaccinated. One-hundred sixty patients (91 fully and 69 partially vaccinated) resulted eligible, showing a 28-day mortality rate of 51.9%. Compared to partially vaccinated, fully vaccinated were younger (69 [60-77.5] vs. 74 [66-79] years, p 0.029), more frequently immunocompromised (39.56% vs. 14.39%, p 0.003), and affected by at least one comorbidity (90.11% vs 78.26%, p 0.045), mainly chronic kidney disease (CKD) (36.26% vs 20.29%, p 0.035). At multivariable analysis, independent predictors of 28-day mortality were as follows: older age [OR 1.05 (CI 95% 1.01-1.08), p 0.005], history of chronic obstructive pulmonary disease (COPD) [OR 3.05 (CI 95% 1.28-7.30), p 0.012], immunosuppression [OR 3.70 (CI 95% 1.63-8.40), p 0.002], and admission respiratory and hemodynamic status [PaO2/FiO2 and septic shock: OR 0.99 (CI 95% 0.98-0.99), p 0.009 and 2.74 (CI 95% 1.16-6.48), p 0.022, respectively].

CONCLUSIONS

Despite a full vaccination cycle, severe COVID-19 may occur in patients with relevant comorbidities, especially immunosuppression and CKD. Regardless the immunization status, predisposing conditions (i.e., older age, COPD, and immunosuppression) and a severe clinical presentation were predictors of 28-day mortality.

Trends (2020-2022) toward Reduced Prevalence of Postcoronavirus Disease Syndrome and Improved Quality of Life for Hospitalized Coronavirus Disease 2019 Patients with Severe Infection and Venous Thromboembolism

The coronavirus disease 2019 (COVID-19) pandemic seems to be at its end. During the first outbreak, alfa was the dominant variant, and in the two following years, delta was the dominant variant. Questions remain about the prevalence and severity of post-COVID syndrome (PCS). We compared the medium-term outcomes of a selected group of patients considered at high risk for PCS: hospitalized patients with severe COVID-19 infection who presented clinical evidence of the acute onset of venous thromboembolism. Weighted Cox regression was used to estimate the adjusted hazard ratios for the risk of early and medium-term complications and quality of life (QoL) in COVID-19 patients developing acute venous thrombo-embolism according to the period of admission to the hospital. The primary outcome was the modification of QoL at a median follow-up of 24 months in patients hospitalized for COVID-19. The secondary outcome was the modification of QoL related to COVID-19 severity. The absolute risk of mortality for hospitalized COVID-19 patients was higher during the first outbreak (risk difference, 19% [95% confidence interval [CI], 16-22%]). Patients with acute onset of thromboembolism during the first outbreak had increased mortality, hospital stay, and need for intensive care unit treatment (p < 0.01). In patients who suffered from severe COVID-19 infection and thromboembolism in the following 2 years, symptoms during follow-up were less common and milder (risk difference 45% [95% CI, 40-52%]. In total, 19 patients were alive at 24 months follow-up: 12 patients (63%) reported important physical symptoms and 10 patients (52%) relevant emotional/mental symptoms. All patients reported reduced QoL in comparison with the preinfection time; in 15 patients (79%), the reduced QoL limited significantly their social and work activities. All patients reported permanent worsening of QoL after discharge from the hospital. Comparing the three different February to April interval years (2020, 2021, and 2022), patients reported a somewhat worse perception of health condition in comparison with the preinfection time, respectively, in 100, 79, and 56% respectively. The findings of our study show reduced prevalence and severity of PCS in the last 2 years. Less virulent variants, herd immunity, and vaccination may played a significant role.

[Retrospective study of the effect of vaccination against SARS-CoV-2 in seriously ill patients admitted to an intensive care unit]

BACKGROUND AND OBJECTIVE

Our study aims to compare the clinical and epidemiological characteristics, length of stay in the ICU, and mortality rates of COVID-19 patients admitted to the ICU who are fully vaccinated, partially vaccinated, or unvaccinated.

PATIENTS AND METHODS

Retrospective cohort study (March 2020-March 2022). Patients were classified into unvaccinated, fully vaccinated, and partially vaccinated groups. We initially performed a descriptive analysis of the sample, a multivariable survival analysis adjusting for a Cox regression model, and a 90-day survival analysis using the Kaplan-Meier method for the death time variable.

RESULTS

A total of 894 patients were analyzed: 179 with full vaccination, 32 with incomplete vaccination, and 683 were unvaccinated. Vaccinated patients had a lower incidence (10% vs. 21% and 18%) of severe ARDS. The survival curve did not show any differences in the probability of surviving for 90 days among the studied groups (p = 0.898). In the Cox regression analysis, only the need for mechanical ventilation during admission and the value of LDH (per unit of measurement) in the first 24 hours of admission were significantly associated with mortality at 90 days (HR: 5.78; 95% CI: 1.36-24.48); p = 0.01 and HR: 1.01; 95% CI: 1.00-1.02; p = 0.03, respectively.

CONCLUSIONS

Patients with severe SARS-CoV-2 disease who are vaccinated against COVID-19 have a lower incidence of severe ARDS and mechanical ventilation than unvaccinated patients.

Characteristics of COVID-19 vaccinated and unvaccinated patients admitted to Careggi University Hospital, Florence, Italy

More than 11.5 billion COVID-19 vaccine doses have been administered around the world. Although vaccine effectiveness for severe infections is reported to be 89.0%, breakthrough infections are common and may lead to severe outcome in fragile population. We conducted a real-world observational study on 420 COVID-19 admitted patients from July 2021 to January 2022 in a tertiary level Italian hospital. We collected patient's vaccination and SARS-CoV-2 serological status, SARS-CoV-2 treatments, oxygen supports, intensive (ICU) and subintensive (sub-ICU) care unit admissions, length of staying (LoS) and in-hospital mortality. One-hundred-seventy-two vaccinated and 248 unvaccinated patients were admitted during the study period. Vaccinated group (Vg) had a significantly more elevated Charlson Comorbidity Index than Unvaccinated group (UVg), and no statistical differences were found in terms of in-hospital mortality, LoS or ICU and sub-ICU admissions. Among Vg, anti-S antibodies were detected in 86.18% of patients (seropositives). Vaccinated seronegative patients' in-hospital mortality was significantly higher than vaccinated seropositive patients (33.33% vs 10.69%, p = 0.0055): in particular, mortality rate in 45-69 years old population was higher in vaccinated seronegative group, and comparable in patients ≥ 70 years old. No differences in terms of outcome were registered between Vg and UVg, taking into account that Vg was considerably older and with more comorbidities. In line with other recent observations, higher mortality rate was evidenced for seronegative vaccinated patients. Primary prophylaxis and early treatments result to be necessary, especially for older and immunosuppressed populations.

Primary SARS-CoV-2 Infections, Re-infections and Vaccine Effectiveness during the Omicron Transmission Period in Healthcare Workers of Trieste and Gorizia (Northeast Italy), 1 December 2021-31 May 2022

Objective: To evaluate the incidence of primary and recurrent COVID-19 infections in healthcare workers (HCWs) routinely screened for SARS-CoV-2 by nasopharyngeal swabs during the Omicron wave. Design: Dynamic Cohort study of HCWs (N = 7723) of the University Health Agency Giuliano Isontina (ASUGI), covering health services of the provinces of Trieste and Gorizia (Northeast Italy). Cox proportional hazard model was employed to estimate the risk of primary as well as recurrent SARS-CoV-2 infection from 1 December 2021 through 31 May 2022, adjusting for a number of confounding factors. Results: By 1 December 2021, 46.8% HCWs of ASUGI had received the booster, 37.2% were immunized only with two doses of COVID-19 vaccines, 6.0% only with one dose and 10.0% were unvaccinated. During 1 March 2020-31 May 2022, 3571 primary against 406 SARS-CoV-2 recurrent infections were counted among HCWs of ASUGI, 59.7% (=2130/3571) versus 95.1% (=386/406) of which occurring from 1 December 2021 through 31 May 2022, respectively. All HCWs infected by SARS-CoV-2 during 1 December 2021 through 31 May 2022 presented mild flu-like disease. Compared to staff working in administrative services, the risk of primary as well as recurrent SARS-CoV-2 infection increased in HCWs with patient-facing clinical tasks (especially nurses and other categories of HCWs) and in all clinical wards but COVID-19 units and community health services. Regardless of the number of swab tests performed during the study period, primary infections were less likely in HCWs immunized with one dose of COVID-19 vaccine. By contrast, the risk of SARS-CoV-2 re-infection was significantly lower in HCWs immunized with three doses (aHR = 0.58; 95%CI: 0.41; 0.80). During the study period, vaccine effectiveness (VE = 1-aHR) of the booster dose declined to 42% against re-infections, vanishing against primary SARS-CoV-2 infections. Conclusions: Though generally mild, SARS-CoV-2 infections and re-infections surged during the Omicron transmission period. Compared to unvaccinated colleagues, the risk of primary SARS-CoV-2 infection was significantly lower in HCWs immunized just with one dose of COVID-19 vaccines. By Italian law, HCWs immunized only with one dose were either suspended or re-assigned to job tasks not entailing patient facing contact; hence, while sharing the same biological risk of unvaccinated colleagues, they arguably had a higher level of protection against COVID-19 infection. By contrast, SARS-CoV-2 re-infections were less likely in HCWs vaccinated with three doses, suggesting that hybrid humoral immunity by vaccination combined with natural infection provided a higher level of protection than vaccination only. In this stage of the pandemic, where SARS-CoV-2 is more infectious yet much less pathogenic, health protection measures in healthcare premises at higher biological risk seem the rational approach to control the transmission of the virus.

Differential Kinetics of Effector and Memory Responses Induced by Three Doses of SARS-CoV-2 mRNA Vaccine in a Cohort of Healthcare Workers

We reported the long-term kinetics of immune response after vaccination and evaluated the immunogenicity after a third dose of mRNA vaccine in 86 healthcare workers. Humoral response was analyzed by measuring anti-spike IgG and SARS-CoV-2 NTAbs titer; cell-mediated response was measured as frequency of IFN-γ producing T-cells and cell proliferation. Memory B cells secreting SARS-CoV-2 RBD-IgG were measured by B-spot assay. At three weeks after the third dose (T4), the frequency of subjects showing NT-Abs titer at the upper detection limit (≥640) was significantly higher than that observed at three weeks after the second dose (26/77; 33.7% vs. 9/77; 11.6%; p = 0.0018). Additionally, at T4, all the subjects reached positive levels of T-cell mediated response (median 110 SFU/106 PBMC, IQR 73-231). While the number of IFNγ-producing T-cells decreased between second and third dose administration, the T-cell proliferative response did not decrease but was sustained during the follow-up. Among T-cell subsets, a higher proliferative response was observed in CD4+ than in CD8+ population. Moreover, even if a decline in antibody response was observed between the second and third dose, a sustained persistence of memory B cells was observed. Subsequently, the third dose did not affect the frequency of memory B cells, while it restored or increased the peak antibody levels detected after the second dose.