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

Abstract

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.