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

Associations between hospital structure, infection control and incidence of hospital-acquired viral respiratory infections: a 10-year surveillance study

BACKGROUND

Protecting patients from hospital-acquired viral respiratory infections is a major challenge, but the hierarchy of measures to achieve this is not yet completely clear.

AIM

To describe the epidemiology of hospital-acquired viral respiratory infections and associations with structural hospital factors and adherence to infection control protocols.

METHODS

Retrospective cohort study conducted over 10 consecutive years (2014-2023) within 27 hospital wards in a 900-bed university hospital in Paris, France. All hospitalized adult patients who were tested for at least one virus on a respiratory sample during their stay were included. Structural factors (percentage of double occupancy rooms) and adherence to infection control protocols by healthcare workers (measured by consumption of alcohol-based hand sanitizer and of facemasks) were included as predictors in the model.

MAIN OUTCOME AND MEASURE

Incidence of hospital-acquired viral respiratory infections, defined by a positive PCR test for at least one respiratory virus, performed at least 5 days after hospital admission. Data were analyzed on ward-year aggregated data, with a linear mixed-effects model.

FINDINGS

Overall, 183 994 viral PCR tests were performed over the study period. Incidence of hospital-acquired viral respiratory infections was 0.57/1000 hospital-days. After adjustment on other factors (mean length of stay, use of PCR testing), incidence of hospital-acquired viral respiratory infections in a given ward was significantly associated with: the incidence of community-acquired viral respiratory infections among patients admitted to the ward (+ 0.10/1000 hospital-days per each additional point of incidence; P < 0.001), the number of double-occupancy rooms (+ 0.04/1000 hospital-days per each 10%-increase of double-occupancy rooms; P = 0.03) and masks consumption (+ 0.33/1000 hospital-days per 10 additional masks used per day; P = 0.04). Similar results were found for double-occupancy rooms (+ 0.01/1000 hospital-days per each 10%-increase of double-occupancy rooms; P = 0.012) in the sub-group analysis of influenza cases.

CONCLUSION

In a given hospital ward, the incidence of community-acquired cases and the proportion of double-occupancy rooms are independently associated with the incidence hospital-acquired viral respiratory infections.

Risk of nosocomial coronavirus disease 2019: comparison between single- and multiple-occupancy rooms

BACKGROUND

There is an ongoing controversy regarding whether single-occupancy rooms are superior to multiple-occupancy rooms in terms of infection prevention. We investigated whether treatment in a multiple-occupancy room is associated with an increased incidence of nosocomial coronavirus disease 2019 (COVID-19) compared with treatment in a single-occupancy room.

METHODS

In this retrospective cohort study, every hospitalization period of adult patients aged ≥ 18 years at a tertiary hospital in Korea from January 1, 2022, to December 31, 2022, was analyzed. If COVID-19 was diagnosed more than 5 days after hospitalization, the case was classified as nosocomial. We estimated the association between the number of patients per room and the risk of nosocomial COVID-19 using a Cox proportional hazards regression model.

RESULTS

In total, 25,143 hospitalizations per room type were analyzed. The incidence rate of nosocomial COVID-19 increased according to the number of patients per room; it ranged from 3.05 to 38.64 cases per 10,000 patient-days between single- and 6-bed rooms, respectively. Additionally, the hazard ratios of nosocomial COVID-19 showed an increasing trend according to the number of patients per room, ranging from 0.14 (95% confidence interval 0.001-1.03) to 2.66 (95% confidence interval 1.60-4.85) between single- and 6-bed rooms, respectively.

CONCLUSIONS

We demonstrated that the incidence of nosocomial COVID-19 increased according to the number of patients per room. To reduce nosocomial infections by respiratory viruses, the use of multiple-occupancy rooms should be minimized.

Nosocomial Coronavirus Disease 2019 during 2020-2021: Role of Architecture and Ventilation

Nosocomial coronavirus disease 2019 (COVID-19) is a major airborne health threat for inpatients. Architecture and ventilation are key elements to prevent nosocomial COVID-19 (NC), but real-life data are challenging to collect. We aimed to retrospectively assess the impact of the type of ventilation and the ratio of single/double rooms on the risk of NC (acquisition of COVID-19 at least 48 h after admission). This study was conducted in a tertiary hospital composed of two main structures (one historical and one modern), which were the sites of acquisition of NC: historical (H) (natural ventilation, 53% single rooms) or modern (M) hospital (double-flow mechanical ventilation, 91% single rooms). During the study period (1 October 2020 to 31 May 2021), 1020 patients presented with COVID-19, with 150 (14.7%) of them being NC (median delay of acquisition, 12 days). As compared with non-nosocomial cases, the patients with NC were older (79 years vs. 72 years; p < 0.001) and exhibited higher mortality risk (32.7% vs. 14.1%; p < 0.001). Among the 150 NC cases, 99.3% were diagnosed in H, mainly in four medical departments. A total of 73 cases were diagnosed in single rooms versus 77 in double rooms, including 26 secondary cases. Measured air changes per hour were lower in H than in M. We hypothesized that in H, SARS-CoV-2 transmission was favored by short-range transmission within a high ratio of double rooms, but also during clusters, via far-afield transmission through virus-laden aerosols favored by low air changes per hour. A better knowledge of the mechanism of airborne risk in healthcare establishments should lead to the implementation of corrective measures when necessary. People's health is improved using not only personal but also collective protective equipment, i.e., ventilation and architecture, thereby reinforcing the need to change institutional and professional practices.