Environmental Contamination of SARS-CoV-2 Delta VOC by COVID-19 Patients Staying in the Hospital for More Than Two Weeks.

Background: Patients infected with SARS-CoV-2 Delta VOC have a longer course of disease. We detected the air, surfaces, and patient's personal items in the wards of the second hospital of Nanjing during the outbreak of the COVID-19 Delta Variant to identify the environmental contamination, which provides a theoretical basis for the prevention and control of COVID-19 variation beads in the future. Methods: In the cross-sectional study, we collected and analyzed clinical features, demographic and epidemiological data, laboratory and swab test results, and surface and air samples of 144 COVID-19 cases. Results: The time from symptom onset to surface sampling was 25 days (IQR, 21 to 33 days). Positive throat swabs were detected in 52(36.1%) patients, of which only 8(5.6%) patients had N or ORF1a/b genes Ct value <35 on the surface sampling day. Among the 692 environmental surface and air specimens collected from 144 COVID-19 cases, 3 specimens (3/692, 0.4%) related to 5 cases (3.5%, 5/144) were detected positive on RT-PCR. Overall, bedside tables (2/144, 1.4%) were most likely to be contaminated, followed by toilet seats (1/81, 1.2%). Conclusion: The environmental contamination by SARS-CoV-2 Delta VOC-infected cases with disease duration of more than two weeks is limited.

[Discussion on the zero-calibration and the zero line in the measurement of central venous pressure and invasive arterial blood pressure].

OBJECTIVE: To figure out the timing of zeroing and the location of the zero line in the central venous pressure (CVP) monitoring and invasive arterial blood pressure (IBP) monitoring, and to provide scientific and accurate data for patients management. METHODS: The liquid vessel models were used to simulate the pressure measurement process of the continuous pressure monitoring system. Based on the theory of fluid mechanics and the knowledge of blood pressure physiology and cardiovascular anatomy, the composition and influencing factors of the pressure in the fluid-filled catheter system during the zeroing and placing the transducer in the zero line of CVP and IBP, were analyzed. RESULTS: The pressure in the liquid-filled catheter system was composed of atmospheric pressure, the pressure of pumping bag, the gravity of the water column (the vertical distance between the liquid level of Murphy's dropper and pressure transducer, ΔH), and the resistance of tube wall. This pressure value is set as a pressure of 0 mmHg (1 mmHg ≈ 0.133 kPa). In the process of pressure measurement, when the pressure transducer was placed at a horizontal position of 10 cm below the highest liquid level of the vessel, the pressure measured at different catheter tip positions was all 10 cmH2O (1 cmH2O ≈ 0.098 kPa); When the pressure transducer was placed at the horizontal position of the highest liquid level of the vessel, the measured pressure is 0 mmHg. CONCLUSIONS: Zeroing should repeatedly be performed only when one or more conditions (atmospheric pressure, pressure of pumping bag, gravity of ΔH water column and resistance of tube wall) are changed. In the measurement process, the pressure transducer should be placed at the zero line position at any time to eliminate the influence of hydrostatic pressure and to ensure the objective and accurate value.

Environmental sampling of the severe acute respiratory syndrome coronavirus 2 Delta variant in the inpatient wards of a hospital in Nanjing.

BACKGROUND: Little is known about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant of concern (VOC)-contaminated environmental surfaces and air in hospital wards admitting COVID-19 cases. Our study was designed to identify high-risk areas of Delta VOC contamination in the hospital and provide suggestions to in-hospital infection control. We analyzed the SARS-CoV-2 Delta VOC contamination in the air and environmental surface samples collected from a hospital in Nanjing, China. METHODS: We collected data on clinical features, laboratory tests, swab tests, and hospital wards, identified the factors associated with environmental contamination, and analyzed patients' hygiene behaviors during hospitalization. RESULTS: A total of 283 environmental surface and air samples were collected from a hospital admitting 36 COVID-19 patients. Twelve swab samples from ten patients were positive. Toilet seats had the highest contamination rate (11.8%), followed by bedside tables (8.2%), garbage bins (5.9%), and bedrails (1.6%). The median time of symptom onset to surface sampling was shorter in the positive environment group than in the negative environment group (11 vs. 18 days; P=0.001). The results indicated that environmental surface contamination was associated with positive anal swabs [odds ratio (OR) 27.183; 95% CI: 2.359-226.063; P=0.003] and the time from symptom onset to surface sampling (OR 0.801; 95% CI: 0.501-0.990; P=0.046). The survey revealed that 33.3% of the patients never cleaned or disinfected their bedside tables or toilets, and 8.3% of them only cleaned their bedside tables or toilets. More than half of the patients often (25%) or always (30.6%) put the used masks on their bedside tables. Only 16.7% of the patients threw the masks into the specific garbage bin for used masks. CONCLUSIONS: The SARS-CoV-2 Delta VOC was detected on environmental surfaces, especially toilet seats and bedside tables, within a median time of 11 days after symptom onset. Our study provided potential predictors for environmental surface contamination, including positive anal swabs and the time from symptom onset to sampling. Disinfecting high-risk environmental surfaces should be emphasized in hospital wards, especially for patients in the early stage of COVID-19.