Epidemiology of healthcare-associated SARS-CoV-2 outbreaks in Germany between March 2020 and May 2022

Non-pharmaceutical infection prevention measures in nosocomial SARS-CoV-2 outbreaks: a retrospective multi-centre cohort study

BACKGROUND

Hospital severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks are relevant for patients and healthcare systems within and beyond the pandemic.

AIM

To explore the characteristics of SARS-CoV-2 outbreaks and their infection prevention and control (IPC) measures during the different pandemic waves.

METHODS

A comprehensive structured template for SARS-CoV-2 outbreaks was developed and filled out by six university hospitals. The main outcome variable was outbreak size (OS).

FINDINGS

A total of 80 outbreaks and 734 infection cases were enrolled between March 2020 and February 2023. In the majority of outbreaks (85%) a contact tracing (CT) team was in place. In 13 (16%) outbreaks the CT team was exclusively responsible for CT, which was negatively linked to OS when adjusting for SARS-CoV-2 waves (estimate (β) = -1.350; standard error (SE) = 0.274; P < 0.0001). Patients as index had a greater association with OS than healthcare workers (HCWs) (β = -0.29; SE = 0.098; P = 0.003). Additionally, the mandatory use of face masks by patients in the presence of HCWs was negatively linked to OS (β = -0.237; SE = 0.08; P = 0.003). The frequency of patient screening during outbreaks varied considerably, whereby higher frequency screenings for SARS-CoV-2 were negatively associated with OS (β = -0.358; SE = 0.109; P = 0.001).

CONCLUSION

Our data provide insights in non-pharmaceutical outbreak prevention and management, revealing that the mandatory use of face masks by patients in the presence of HCWs and a high patient screening frequency in ongoing outbreaks were significantly associated with smaller outbreaks. Further studies are required to allow for generalizability.

Proposed new definition for hospital-acquired SARS-CoV-2 infections: results of a confirmatory factor analysis

Objective

The present study aims to develop and discuss an extension of hospital-acquired severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections (HA-SIs) definition which goes beyond the use of time parameters alone.

Design

A confirmatory factor analysis was carried out to test a suitable definition for HA-SI.

Setting and Patients

A two-center cohort study was carried out at two tertiary public hospitals in the German state of lower Saxony. The study involved a population of 366 laboratory-confirmed SARS-CoV-2-infected inpatients enrolled between March 2020 and August 2023.

Results

The proposed model shows adequate fit indices (CFI.scaled = 0.959, RMSEA = 0.049). A descriptive comparison with existing classifications revealed strong features of our model, particularly its adaptability to specific regional outbreaks.

Conclusion

The use of the regional incidence as a proxy variable to better define HA-SI cases represents a pragmatic and novel approach. The model aligns well with the latest scientific results in the literature. This work successfully unifies, within a single model, variables which the recent literature described as significant for the onset of HA-SI. Further potential improvements and adaptations of the model and its applications, such as automating the categorization process (in terms of hospital acquisition) or employing a comparable model for hospital-acquired influenza classification, are subjects open for discussion.

Morbidity and Mortality of Hospital-Onset SARS-CoV-2 Infections Due to Omicron Versus Prior Variants : A Propensity-Matched Analysis

BACKGROUND

Many hospitals have scaled back measures to prevent nosocomial SARS-CoV-2 infection given large decreases in the morbidity and mortality of SARS-CoV-2 infections for most people. Little is known, however, about the morbidity and mortality of nosocomial SARS-CoV-2 infections for hospitalized patients in the Omicron era.

OBJECTIVE

To estimate the effect of nosocomial SARS-CoV-2 infection on hospitalized patients' outcomes during the pre-Omicron and Omicron periods.

DESIGN

Retrospective matched cohort study.

SETTING

5 acute care hospitals in Massachusetts, December 2020 to April 2023.

PATIENTS

Adults testing positive for SARS-CoV-2 on or after hospital day 5, after negative SARS-CoV-2 test results on admission and on hospital day 3, were matched to control participants by hospital, service, time period, days since admission, and propensity scores that incorporated demographics, comorbid conditions, vaccination status, primary diagnosis category, vital signs, and laboratory test values.

MEASUREMENTS

Primary outcomes were hospital mortality and time to discharge. Secondary outcomes were intensive care unit (ICU) admission, need for advanced oxygen support, discharge destination, hospital-free days, and 30-day readmissions.

RESULTS

There were 274 cases of hospital-onset SARS-CoV-2 infection during the pre-Omicron period and 1037 cases during the Omicron period (0.17 vs. 0.49 cases per 100 admissions). Patients with hospital-onset SARS-CoV-2 infection were older and had more comorbid conditions than those without. During the pre-Omicron period, hospital-onset SARS-CoV-2 infection was associated with increased risk for ICU admission, increased need for high-flow oxygen, longer time to discharge (median difference, 4.7 days [95% CI, 2.9 to 6.6 days]), and higher mortality (risk ratio, 2.0 [CI, 1.1 to 3.8]) versus matched control participants. During the Omicron period, hospital-onset SARS-CoV-2 infection remained associated with increased risk for ICU admission and increased time to discharge (median difference, 4.2 days [CI, 3.6 to 5.0 days]). The association with increased hospital mortality was attenuated but still significant (risk ratio, 1.6 [CI, 1.2 to 2.3]).

LIMITATION

Residual confounding may be present.

CONCLUSION

Hospital-onset SARS-CoV-2 infection during the Omicron period remains associated with increased morbidity and mortality.

PRIMARY FUNDING SOURCE

Harvard Medical School Department of Population Medicine.

Impact of COVID-19 on healthcare-associated infections and antimicrobial use in Italy, 2022

BACKGROUND

It is unknown whether COVID-19 patients are at higher risk due to demographic and clinical characteristics associated with higher COVID-19 infection risk and severity of infection, or due to the disease and its management.

AIM

To assess the impact of COVID-19 on healthcare-associated infection (HAI) transmission and antimicrobial use (AMU) prevalence during the later stages of the pandemic.

METHODS

A point-prevalence survey (PPS) was conducted among 325 acute care hospitals of 19 out of 21 Regions of Italy, during November 2022. Non-COVID-19 patients were matched to COVID-19 patients according to age, sex, and severity of underlying conditions. HAI and AMU prevalence were calculated as the percentage of patients with at least one HAI or prescribed at least one antimicrobial over all included patients, respectively.

FINDINGS

In total, 60,403 patients were included, 1897 (3.14%) of which were classified as COVID-19 patients. Crude HAI prevalence was significantly higher among COVID-19 patients compared to non-COVID-19 patients (9.54% vs 8.01%; prevalence rate ratio (PRR): 1.19; 95% confidence interval (CI): 1.04-1.38; P < 0.05), and remained higher in the matched sample; however, statistical significance was not maintained (odds ratio (OR): 1.25; 95% CI: 0.99-1.59; P = 0.067). AMU prevalence was significantly higher among COVID-19 patients prior to matching (46.39% vs 41.52%; PRR: 1.21; 95% CI: 1.11-1.32; P < 0.001), and significantly lower after matching (OR: 0.77; 95% CI: 0.66-0.89; P < 0.001).

CONCLUSION

COVID-19 patients could be at higher HAI risk due to underlying clinical conditions and the intensity of healthcare needs. Further efforts should be dedicated to antimicrobial stewardship among COVID-19 patients.

Ventilator-Associated Pneumonia, Ventilator-Associated Events, and Nosocomial Respiratory Viral Infections on the Leeside of the Pandemic

The COVID-19 pandemic has had an unprecedented impact on population health and hospital operations. Over 7 million patients have been hospitalized for COVID-19 thus far in the United States alone. Mortality rates for hospitalized patients during the first wave of the pandemic were > 30%, but as we enter the fifth year of the pandemic hospitalizations have fallen and mortality rates for hospitalized patients with COVID-19 have plummeted to 5% or less. These gains reflect lessons learned about how to optimize respiratory support for different kinds of patients, targeted use of therapeutics for patients with different manifestations of COVID-19 including immunosuppressants and antivirals as appropriate, and high levels of population immunity acquired through vaccines and natural infections. At the same time, the pandemic has helped highlight some longstanding sources of harm for hospitalized patients including hospital-acquired pneumonia, ventilator-associated events (VAEs), and hospital-acquired respiratory viral infections. We are, thankfully, on the leeside of the pandemic at present; but the large increases in ventilator-associated pneumonia (VAP), VAEs, bacterial superinfections, and nosocomial respiratory viral infections associated with the pandemic beg the question of how best to prevent these complications moving forward. This paper reviews the burden of hospitalization for COVID-19, the intersection between COVID-19 and both VAP and VAEs, the frequency and impact of hospital-acquired respiratory viral infections, new recommendations on how best to prevent VAP and VAEs, and current insights into effective strategies to prevent nosocomial spread of respiratory viruses.

Association of institutional masking policies with healthcare-associated SARS-CoV-2 infections in Swiss acute care hospitals during the BA.4/5 wave (CH-SUR study): a retrospective observational study

BACKGROUND

In the initial phase of the SARS-CoV-2 pandemic, masking has been widely accepted in healthcare institutions to mitigate the risk of healthcare-associated infection. Evidence, however, is still scant and the role of masks in preventing healthcare-associated SARS-CoV-2 acquisition remains unclear.We investigated the association of variation in institutional mask policies with healthcare-associated SARS-CoV-2 infections in acute care hospitals in Switzerland during the BA.4/5 2022 wave.

METHODS

SARS-CoV-2 infections in hospitalized patients between June 1 and September 5, 2022, were obtained from the "Hospital-based surveillance of COVID-19 in Switzerland"-database and classified as healthcare- or community-associated based on time of disease onset. Institutions provided information regarding institutional masking policies for healthcare workers and other prevention policies. The percentage of healthcare-associated SARS-CoV-2 infections was calculated per institution and per type of mask policy. The association of healthcare-associated SARS-CoV-2 infections with mask policies was tested using a negative binominal mixed-effect model.

RESULTS

We included 2'980 SARS-CoV-2 infections from 13 institutions, 444 (15%) were classified as healthcare-associated. Between June 20 and June 30, 2022, six (46%) institutions switched to a more stringent mask policy. The percentage of healthcare-associated infections subsequently declined in institutions with policy switch but not in the others. In particular, the switch from situative masking (standard precautions) to general masking of HCW in contact with patients was followed by a strong reduction of healthcare-associated infections (rate ratio 0.39, 95% CI 0.30-0.49). In contrast, when compared across hospitals, the percentage of health-care associated infections was not related to mask policies.

CONCLUSIONS

Our findings suggest switching to a more stringent mask policy may be beneficial during increases of healthcare-associated SARS-CoV-2 infections at an institutional level.

From wild-type to Omicron: changes in SARS-CoV-2 hospital cluster dynamics. Observations from a German tertiary care hospital

Aim

SARS-CoV-2 hospital clusters are a challenge for healthcare systems. There is an increased risk of infection for both healthcare workers (HCWs) and patients; cluster countermeasures are also a drain on resources for the wards affected. We analysed to which extent characteristics and dynamics of SARS-CoV-2 clusters varied throughout the pandemic at a German university hospital.

Methods

Patient and/or HCW clusters from 10/2020 to 04/2022 were included in the study and grouped by virus variant into i.) clusters comprised of the presumably predominant wild-type, Alpha or Delta (WAD) SARS-COV-2 variants, and ii.) clusters comprised predominantly of Omicron subtype cases. The two groups were compared for specific characteristics and dynamics.

Results

Forty-two SARS-CoV-2 clusters and 528 cases were analysed. Twenty-one clusters and 297 cases were attributed to the WAD and 21 clusters and 231 cases to the Omicron group. There were no significant differences in median size (8 vs. 8 cases, p=0.94) or median duration (14 vs. 12 days; p=0.48), nor in the percentage of HCWs involved (46.8% vs. 50.2%; p=0.48). Patients in the WAD group were older (median 75 vs. 68 years of age; p≤0.05). The median time from cluster onset to case onset was significantly shorter for the Omicron group (median 6 vs. 11 days; p≤0.05).

Conclusions

Omicron clusters exhibited a more rapid dynamic, forcing all parties involved to adapt to the increased workload. Compared to excessive community case counts, constant Omicron cluster-affiliated case counts and stable cluster characteristics suggest an improved compliance with IPC countermeasures.

In Support of Universal Admission Testing for SARS-CoV-2 During Significant Community Transmission

Many hospitals have stopped or are considering stopping universal admission testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We discuss reasons why admission testing should still be part of a layered system to prevent hospital-acquired SARS-CoV-2 infections during times of significant community transmission. These include the morbidity of SARS-CoV-2 in vulnerable patients, the predominant contribution of presymptomatic and asymptomatic people to transmission, the high rate of transmission between patients in shared rooms, and data suggesting surveillance testing is associated with fewer nosocomial infections. Preferences of diverse patient populations, particularly the hardest-hit communities, should be surveyed and used to inform prevention measures. Hospitals' ethical responsibility to protect patients from serious infections should predominate over concerns about costs, labor, and inconvenience. We call for more rigorous data on the incidence and morbidity of nosocomial SARS-CoV-2 infections and more research to help determine when to start, stop, and restart universal admission testing and other prevention measures.

Discontinuation of Universal Admission Testing for SARS-CoV-2 and Hospital-Onset COVID-19 Infections in England and Scotland

This quality improvement study examines the association between the discontinuation of universal admission testing for SARS-CoV-2 infections and hospital-onset SARS-CoV-2 infections in England and Scotland.