Risk factors for nosocomial SARS-CoV-2 infections in patients: results from a retrospective matched case-control study in a tertiary care university center

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.

A Bayesian approach to identifying the role of hospital structure and staff interactions in nosocomial transmission of SARS-CoV-2

Nosocomial infections threaten patient safety, and were widely reported during the COVID-19 pandemic. Effective hospital infection control requires a detailed understanding of the role of different transmission pathways, yet these are poorly quantified. Using patient and staff data from a large UK hospital, we demonstrate a method to infer unobserved epidemiological event times efficiently and disentangle the infectious pressure dynamics by ward. A stochastic individual-level, continuous-time state-transition model was constructed to model transmission of SARS-CoV-2, incorporating a dynamic staff-patient contact network as time-varying parameters. A Metropolis-Hastings Markov chain Monte Carlo (MCMC) algorithm was used to estimate transmission rate parameters associated with each possible source of infection, and the unobserved infection and recovery times. We found that the total infectious pressure exerted on an individual in a ward varied over time, as did the primary source of transmission. There was marked heterogeneity between wards; each ward experienced unique infectious pressure over time. Hospital infection control should consider the role of between-ward movement of staff as a key infectious source of nosocomial infection for SARS-CoV-2. With further development, this method could be implemented routinely for real-time monitoring of nosocomial transmission and to evaluate interventions.

Incidence and outcome of hospital-acquired COVID-19 infections in secondary and tertiary care hospitals in the era of COVID-19 vaccinations

Objective

Hospital-acquired (HA) COVID-19 infections are known to increase morbidity and mortality. The aim of this study was to investigate the incidence and outcome of HA COVID-19 in different specialties across the wards in 18 hospitals belonging to the Helsinki University Hospital (HUH) responsible for secondary and tertiary care of a population of 1.8 million.

Design

Retrospective population-based cohort study.

Setting

Secondary and tertiary care hospitals.

Patients

Inpatients with HA COVID-19 infection.

Methods

The HA COVID-19 infections with patient characteristics were retrospectively searched from HUH patient database from 1st October 2021 to 31st March 2022. All positive SARS-CoV-2 nucleic acid amplification tests (NAATs) from any ward were reviewed. The COVID-19 infection was classified as HA if a notification of HA infection was done or SARS-CoV-2 NAAT was positive ≥6 days after hospital admission or medical records revealed a known exposure for COVID-19 during hospital stay.

Results

177 HA COVID-19 infections were retrieved with an incidence of 0.55 per 1000 patient days. Of these patients, 71 (40%) were treated in medicine, 52 (29%) in operative, and 54 (31%) in psychiatric wards, leading to incidences of 0.51, 0.39, and 1.10 per 1,000 patient days, respectively. In association with COVID-19, 16 (23%) in medicine, 3 (6%) in operative, and 1 (2%) patient in psychiatric wards deceased. Of the deceased patients, 16 (80%) had received at least one COVID-19 vaccine.

Conclusions

Hospital-acquired COVID-19 infections in omicron era were related to high mortality, especially among patients in medicine wards who also had good vaccination coverage.

The importance of viruses in ventilator-associated pneumonia

OBJECTIVE

Ventilator-associated pneumonia (VAP) remains a challenge. The importance of viruses in VAP is not established. We sought to determine the prevalence of viruses in VAP and the outcomes of viral VAP.

DESIGN

Retrospective study of VAP over 3 years. The frequency of a viral process represented the primary endpoint. Clinical outcomes served as secondary endpoints. We identified variables independently associated with a virus and conducted sensitivity analyses to assess the interaction between type of infection and patient characteristics.

SETTING

Tertiary-care referral center.

PATIENTS

The final cohort consisted of 710 patients and a virus was isolated in 5.1%.

INTERVENTIONS

None.

RESULTS

The most common viruses included: rhinovirus, influenza A, and cytomegalovirus. Baseline characteristics were similar between those with and without viral infections. In logistic regression, immunosuppression (adjusted odds ratio [aOR], 2.97; 95% confidence interval [CI], 1.44-6.14) and stem-cell transplantation (SCT, aOR, 3.58; 95% CI, 1.17-10.99) were independently associated with a virus. The presence of either variable performed poorly as a screening test for a virus. In-hospital (22.4% vs 21.6%; P = .869) and 30-day (32.8% vs 27.9%; P = .448) mortality rates were similar between the cohorts, respectively. Sensitivity analyses restricted to patients without a mixed viral and bacterial infection or those who were immunocompetent yielded similar results.

CONCLUSION

Although infrequent, a range of viruses may cause VAP. Viruses more often complicate SCT and immunosuppression, but one can isolate viruses in immunocompetent subjects. Viral VAP produces severe infection and results in high mortality rates. Clinical features do not differentiate viral from nonviral VAP.

Patient and ward related risk factors in a multi-ward nosocomial outbreak of COVID-19: Outbreak investigation and matched case-control study

BACKGROUND

Risk factors for nosocomial COVID-19 outbreaks continue to evolve. The aim of this study was to investigate a multi-ward nosocomial outbreak of COVID-19 between 1st September and 15th November 2020, occurring in a setting without vaccination for any healthcare workers or patients.

METHODS

Outbreak report and retrospective, matched case-control study using incidence density sampling in three cardiac wards in an 1100-bed tertiary teaching hospital in Calgary, Alberta, Canada. Patients were confirmed/probable COVID-19 cases and contemporaneous control patients without COVID-19. COVID-19 outbreak definitions were based on Public Health guidelines. Clinical and environmental specimens were tested by RT-PCR and as applicable quantitative viral cultures and whole genome sequencing were conducted. Controls were inpatients on the cardiac wards during the study period confirmed to be without COVID-19, matched to outbreak cases by time of symptom onset dates, age within ± 15 years and were admitted in hospital for at least 2 days. Demographics, Braden Score, baseline medications, laboratory measures, co-morbidities, and hospitalization characteristics were collected on cases and controls. Univariate and multivariate conditional logistical regression was used to identify independent risk factors for nosocomial COVID-19.

RESULTS

The outbreak involved 42 healthcare workers and 39 patients. The strongest independent risk factor for nosocomial COVID-19 (IRR 3.21, 95% CI 1.47-7.02) was exposure in a multi-bedded room. Of 45 strains successfully sequenced, 44 (97.8%) were B.1.128 and differed from the most common circulating community lineages. SARS-CoV-2 positive cultures were detected in 56.7% (34/60) of clinical and environmental specimens. The multidisciplinary outbreak team observed eleven contributing events to transmission during the outbreak.

CONCLUSIONS

Transmission routes of SARS-CoV-2 in hospital outbreaks are complex; however multi-bedded rooms play a significant role in the transmission of SARS-CoV-2.

Risk factors for nosocomial COVID-19 in a French university hospital

OBJECTIVES

Prevention strategies implemented by hospitals to reduce nosocomial transmission of SARS-CoV-2 sometimes failed. Our aim was to determine the risk factors for nosocomial COVID-19.

PATIENTS AND METHODS

A case-control study was conducted (September 1, 2020-January 31, 2021) with adult patients hospitalized in medical or surgical units. Infants or patients hospitalized in ICU were excluded. Cases were patients with nosocomial COVID-19 (clinical symptoms and RT-PCR+ for SARS-CoV-2 or RT-PCR+ for SARS-CoV-2 with Ct ≤28 more than 5days after admission); controls were patients without infection (RT-PCR- for SARS-CoV-2 >5 days after admission). They were matched according to length of stay before diagnosis and period of admission. Analyses were performed with a conditional logistic regression.

RESULTS

A total of 281 cases and 441 controls were included. In the bivariate analysis, cases were older (OR per 10years: 1.22; 95%CI [1.10;1.36]), had more often shared a room (OR: 1.74; 95%CI [1.25;2.43]) or a risk factor for severe COVID-19 (OR: 1.94; 95%CI [1.09;3.45]), were more often hospitalized in medical units [OR: 1.59; 95%CI [1.12;2.25]), had higher exposure to contagious health care workers (HCW; OR per 1person-day: 1.12; 95%CI [1.08;1.17]) and patients (OR per 1 person-day: 1.11; 95%CI [1.08;1.14]) than controls. In an adjusted model, risk factors for nosocomial COVID-19 were exposure to contagious HCW (aOR per 1person-day: 1.08; 95%CI [1.03;1.14]) and to contagious patients (aOR per 1person-day: 1.10; 95%CI [1.07;1.13]).

CONCLUSIONS

Exposure to contagious professionals and patients are the main risk factors for nosocomial COVID-19.

Impact of the COVID-19 pandemic on the diagnosis and treatment of onco-hematologic patients: a discussion paper

We do not know the precise figure for solid organ tumors diagnosed each year in Spain and it is therefore difficult to calculate whether there has been a decrease in cancer diagnoses as a consequence of the pandemic. Some indirect data suggest that the pandemic has worsened the stage at which some non-hematological neoplasms are diagnosed. Despite the lack of robust evidence, oncology patients seem more likely to have a poor outcome when they contract COVID-19. The antibody response to infection in cancer patients will be fundamentally conditioned by the type of neoplasia present, the treatment received and the time of its administration. In patients with hematological malignancies, the incidence of infection is probably similar or lower than in the general population, due to the better protective measures adopted by the patients and their environment. The severity and mortality of COVID-19 in patients with hematologic malignancies is clearly higher than the general population. Since the immune response to vaccination in hematologic patients is generally worse than in comparable populations, alternative methods of prevention must be established in these patients, as well as actions for earlier diagnosis and treatment. Campaigns for the early diagnosis of malignant neoplasms must be urgently resumed, post-COVID manifestations should be monitored, collaboration with patient associations is indisputable and it is urgent to draw the right conclusions to improve our preparedness to fight against possible future catastrophes.

An outbreak of infection due to severe acute respiratory corona virus-2 in a neonatal unit from a low and middle income setting

Introduction

The provision of kangaroo mother care (KMC) involving continuous skin-to-skin care (SSC) is an important intervention in neonatal care, which is recommended even when women are infected with severe acute respiratory syndrome coronavirus (SARS-CoV-2). We report on a nosocomial outbreak of SARS-CoV-2 infections in a KMC ward.

Methods

Contact tracing was conducted following the diagnosis of SARS-CoV-2 in a mother lodging in the KMC ward. All mother-newborn dyads in the KMC and healthcare workers (HCW) were tested for SARS-CoV-2 within 24-72 h of diagnosing the index case. Nasopharyngeal swab samples were obtained and tested from contacts, with a nucleic acid amplification test (NAAT) assay. Next-generation sequencing was done on positive samples. The secondary attack rate (SAR) was calculated assuming that the mother who presented with symptoms was the source of infection.

Results

Twelve (70.6%) of 17 mothers and 8 (42.1%) of 19 neonates who were in the KMC ward with the index case were found to be positive with SARS-CoV-2. Seven (87.5%) of the 8 neonates who tested positive had mothers who also tested positive. Seventy-five percent (9/12) of the mothers and 62.5% (5/8) of the neonates who tested positive were asymptomatic. Eight (27.6%) of 29 HCW were found to be positive and were all asymptomatic. One neonate died from Acinetobacter baumannii sepsis, and his post-mortem lung histopathology showed features compatible with SARS-CoV-2 pneumonia. The sequencing of 13 specimens, which included 1 mother-newborn dyad, indicated clustering to the same phylogenetic lineage with identical mutations. In assessing for factors contributing to this outbreak, it was found that spaces between beds were less than 1 m and mothers had their meals around the same table at the same time.

Conclusion

We report on a nosocomial outbreak of SARS-CoV-2 in a KMC ward, affecting a high number of mothers and neonates, and to a lesser extent HCWs. Although it is difficult to point to the index case as the source of this outbreak, as asymptomatic individuals can spread infection, the inadequate adherence to non-pharmaceutical interventions was assessed to have contributed to the spread of infection. This highlights the need for awareness and adherence to mitigation strategies to avoid SARS-CoV-2 outbreaks.

Infection control strategies for patients and accompanying persons during the COVID-19 pandemic in German hospitals: a cross-sectional study in March-April 2021

BACKGROUND

Patients are at risk of nosocomial COVID-19 infection. The role of accompanying persons/visitors as potential infection donors is not yet well researched, but the risk will be influenced by prevention measures recommended by infection control practitioners.

AIM

To collect information about COVID-19 infection control strategies for patients and accompanying persons from infection control practitioners in German hospitals.

METHODS

A cross-sectional questionnaire was developed, ethically approved, pre-tested and formatted as an online tool. Infection control practitioners in 987 randomly selected German hospitals were invited to participate in March and April 2021. For statistical analysis, the hospitals were categorized as small (0-499 beds) or large (≥500 beds).

FINDINGS

One hundred surveys were completed (response rate: 10%). A higher proportion of large (71%) than small (49%) hospitals let patients decide freely whether to wear medical or FFP2 masks. Most hospitals reported spatial separation for COVID-19 patients and non-COVID-19 cases (38%) or additionally for suspected COVID-19 cases (53%). A separation of healthcare teams for these areas existed in 54% of the hospitals. Accompaniment bans were more prevalent in large (52%) than in small hospitals (29%), but large hospitals granted more exemptions.

CONCLUSION

The decision as to whether to separate areas and teams seemed to depend on the hospital's structural conditions, therefore impairing the implementation of recommendations. Accompaniment regulations differ between hospital sizes and may depend on patient numbers, case type/severity and patients' requirements. In the dynamic situation of a pandemic, it can be difficult to stay up to date with findings and recommendations on infection control.

Nosocomial Outbreak by Delta Variant From a Fully Vaccinated Patient

BACKGROUND

The potential for a nosocomial outbreak of coronavirus disease 2019 (COVID-19) from a fully vaccinated individual is largely unknown.

METHODS

In October 2021, during the time when the delta variant was dominant, a nosocomial outbreak of COVID-19 occurred in two wards in a tertiary care hospital in Seoul, Korea. We performed airflow investigations and whole-genome sequencing (WGS) of the virus.

RESULTS

The index patient developed symptoms 1 day after admission, and was diagnosed with COVID-19 on day 4 post-admission. He was fully vaccinated (ChAdOx1 nCoV-19) 2 months before the diagnosis. Three inpatients and a caregiver in the same room, two inpatients in an adjacent room, two inpatients in rooms remote from the index room, and one nurse on the ward tested positive. Also, two resident doctors who stayed in an on-call room located on the same ward tested positive (although they had no close contact), as well as a caregiver who stayed on an adjacent ward, and a healthcare worker who had casual contact with this caregiver. Samples from five individuals were available for WGS, and all showed ≤ 1 single-nucleotide polymorphism difference. CCTV footage showed that the index case walked frequently in the corridors of two wards. An airflow study showed that the air from the corridor flowed into the resident on-call room, driven by an air circulator that was always turned on.

CONCLUSION

Transmission of severe acute respiratory syndrome coronavirus 2 from a fully vaccinated index occurred rapidly via the wards and on-call room. Care must be taken to not use equipment that can change the airflow.