Effect Analysis of Different Environmental Disinfection Methods on Reducing Contamination of Surfaces by the Omicron BA.2.2 Variant of SARS-CoV-2 and the Characteristics of Fomite Contamination in the Fever Clinic in the Out-Broken of Shanghai

This study aimed to investigate the effect of different environmental disinfection methods on reducing contaminated surfaces (CSs) by the Omicron BA.2.2 variant of SARS-CoV-2 in the fever clinic between March 20 and May 30, 2022, and to analyze the influences and related factors of CSs. This study includes survey data from 389 positive patients (SPPs) and 204 CSs in the fever clinic, including the CS type, disinfection method, length of time spent in the clinic, cycle threshold (CT) value, name, age, weight, mask type, mask-wearing compliance, hand-mouth touch frequency and sex. Associations between study variables and specified outcomes were explored using univariate regression analyses. Mask-wearing compliance had a significant negative correlation with CSs ( r = − 0.446, P = 0.037). Among the 389 SPPs, 22 SPPs (CRP, 5.66%) caused CSs in the separate isolation room. A total of 219 SPPs (56.30%) were male. The mean age of SPPs was 4.34 ± 3.92 years old, and the mean CT value was 12.44 ± 5.11. In total, 9952 samples with exposure history were taken, including 204 (2.05%) CSs. Among the CSs, the positive rate of flat surfaces was the highest in public areas (2.52%) and separate isolation rooms (4.75%). Disinfection methods of ultraviolet radiation + chemical irradiation significantly reduced the CSs in both the public area (0% vs. 4.56%) and the separate isolation room (0.76% vs. 2.64%) compared with the chemical method alone ( P < 0.05). Compared with ordinary SPPs, CRPs were older (6.04 year vs. 4.23 year), and the male proportion was higher (72.73% vs. 55.31%). In particular, it was found that SPPs contaminated their surroundings and therefore imposed risks on other people. Environmental disinfection with ultraviolet radiation + chemical treatment should be emphasized. The findings may be useful to guide infection control practices for the Omicron BA.2.2 variant of SARS-CoV-2.