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Exposure to Airborne SARS-CoV-2 in Four Hospital Wards and Icus of Cyprus. A Detailed Study Accounting for Day-to-Day Operations and Aerosol Generating Procedures
19 Pages Posted: 11 Apr 2022 Publication Status: Published
Abstract
In any infectious disease, understanding the modes of transmission is key to selecting effective public health measures. In the case of CoViD-19 spread, the strictness of the imposed measures outlined the lack of understanding on how SARS-CoV-2 transmits, particularly via airborne pathways. With the aim to characterize the transmission dynamics of airborne SARS-CoV-2, 165 and 62 air and environmental samples, respectively, were collected in four CoViD-19 wards and ICUs in Cyprus and analyzed by RT-PCR. An alternative method for SARS-CoV-2 detection in air that provides comparable results but is less cumbersome and time demanding, is also suggested. Taking into account that all clinics employed 14 regenerations per hour of full fresh air inside patient rooms, it was hypothesized that the viral levels and the frequency of positive samples would be minimum outside of the rooms. However, it is shown that leaving the door opened in patient rooms hinders the efficiency of the ventilation system applied, allowing the virus to escape. As a result, the highest observed viral levels (135 copies m-3) were observed in the corridor of a ward and the frequency of positive samples in the same area was comparable to that inside a two-bed cohort. SARS-CoV-2 in that corridor was found primarily to lie in the coarse mode, at sizes between 1.8 and 10 μm. Similar to previous studies, the frequency of positive samples and viral levels were the lowest inside intensive care units. However if a patient with sufficient viral load (Ct-value 31), was targeted during the application of aerosol generating procedures, positive samples with viral levels below 45 copies m-3 were acquired within a 2 m distance. Our results suggest that a robust ventilation system can prevent unnecessary exposure to SARS-CoV-2 but with limitations related to foot traffic or the operations taking place at the time.
Funding Information: JS and MP acknowledge financial contribution from AIR-COVID NETWORK (CONCEPT-COVID/0420/0014) and CURE-SARS (CONCEPT COVID/0420/0015) projects, which are co-financed by the European Regional Development Fund and the Republic of Cyprus through the Research and Innovation Foundation”. This study has also been supported financially by the H2020-EMME-CARE (GA 856612) research grants.
Conflict of Interests: LP is the Deputy Director of the Department of Intensive Care Medicine at the Nicosia General Hospital (NIC1 and NIC2). MF works at NIC1 as a Nurse and Clinical Educator. The remaining authors of this work declare no competing interests.
Ethical Approval: This study was conducted under the approval of the Cyprus national bioethics committee (approval EEBK EΠ 2020.01.123), which allowed us to collect air and environmental samples inside hospitals, provided that the patient’s anonymity was secured. During this work, the information collected included; the number of patients inside the cohorts, their sex, and the number of days since their admission, without any personal information disclosed. Apart from the written consent by each ward’s head, the patients were notified of their participation to the experiment by at least one poster placed inside their rooms. Their verbal consent was always sought for even though it was not a perquisite of the bioethics approval. In case a complaint was raised action was taken by removing the sampler from the room completely or by reducing sampling during periods where it would not pose an annoyance (eg not during nightime).
Keywords: airborne SARS-CoV-2 fast detection, Occupational Health, aerosol generating procedures, SARS-CoV-2 size distribution
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