ABSTRACT
Background and Objectives: Coronavirus disease 2019 (COVID-19) is a pandemic caused by the novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Knowing the virus's behavior and its persistence in different environments are crucial and will lead to the proper management of the disease. In this study, air, surface, and sewage samples were taken from different parts of referral hospitals for COVID-19. Materials and Methods: Air samples were taken with impinger, surface samples with swabs, and sewage samples were taken from the hospital wastewater treatment plant. After viral genome extraction, a real-time RT-PCR test was applied to confirm the presence of SARS-CoV-2 RNA in the collected samples. Results: The virus genome could be traced in the wards and wastewater related to hospitalized COVID-19 patients. Overally, 29%, 16%, and 37.5% of air, surface, and sewage samples were positive for the SARS-CoV-2 genome, respectively. Conclusion: Findings of such studies provide valuable results regarding the degree of contamination of hospital environments and the risk of virus transmission in different environments and among hospital staff and patients.
ABSTRACT
SCIENTIFIC BACKGROUND: Environmental sampling of SARS-CoV-2 is a fundamental tool for evaluating the effectiveness of non-specific prophylaxis measures in counteracting virus spread. The purpose of our work was to evaluate the effectiveness of the different sampling methods in the hospital setting to assess their correlation with the structural, functional, and operational situation of the monitored departments and to define the dynamics of the spread of the virus in indoor environments. METHODS: The monitoring (air bubbling sampling, surface wipe test) was carried out at the San Martino Polyclinic Hospital (Genoa, Italy) in the period since April 2020 to June 2021. The presence of viral RNA in the collected samples was evaluated by qPCR. The infection capacity of the samples collected was also evaluated by an in vitro challenge test on cells sensitive to SARS-CoV-2 infection. RESULTS: The percentage of positivity with respect to the number of tests performed (sensitivity) were air bubbler 50%, wipe test 17%, and challenge test 11%. Only 20% of the samples tested positive in the wipe test and 43% of the samples tested positive in the bubbler sampling were also positive in the challenge test. All the positivity obtained was detected at a distance of less than 2 m and height of less than 1.5 from COVID-19 patients. CONCLUSIONS: Environmental contamination from SARS-CoV-2 detected at the San Martino Polyclinic Hospital is found lower than similar assessments performed in other hospitals both in Italy and abroad. Our study predicted that environmental monitoring of SARS-CoV-2 must be carried out in an integrated way by not using a single sampling method, as each individual test has a different biological significance and performance. However, the virus detected by wipe test only is often a degraded viral fragment and not an intact infecting virion.