Airborne contamination of COVID-19 in hospitals: a scoping review of the current evidence

Abstract

Introduction A controversy remains worldwide regarding the transmission routes of SARS-CoV-2 in hospital settings. We reviewed the current evidence on the air contamination with SARS-CoV-2 in hospital settings, and the factors associated to the contamination including the viral load and the particles size. Methods The MEDLINE, Embase, Web of Science databases were systematically interrogated for original English-language articles detailing COVID-19 air contamination in hospital settings between 1 December 2019 and 21 July 2020. This study was conducted in accordance with the PRISMA-ScR guidelines. The positivity rate of SARS-CoV-2 viral RNA and culture were described and compared according to the setting, clinical context, air ventilation system, and distance from patient. The SARS-CoV-2 RNA concentrations in copies per m3 of air were pooled and their distribution were described by hospital areas. Particle sizes and SARS-CoV-2 RNA concentrations in copies or TCID50 per m3 were analysed after categorization of sizes in <1 micrometers, 1-4 micrometers, and >4 micrometers. Results Among 2,034 records identified, 17 articles were included in the review. Overall, 27.5% (68/247) of air sampled from close patients environment were positive for SARS-CoV-2 RNA, without difference according to the setting (ICU: 27/97, 27.8%; non-ICU: 41/150, 27.3%; p=0.93), the distance from patients (<1 meter: 1/64, 1.5%; 1-5 meters: 4/67, 6%; p=0.4). In other areas, the positivity rate was 23.8% (5/21) in toilets, 9.5% (20/221) in clinical areas, 12.4% (15/121) in staff areas, and 34.1% (14/41) in public areas. A total of 78 viral cultures were performed in three studies, and 3 (4%) were positive, all from close patients environment. The median SARS-CoV-2 RNA concentrations varied from 1.103 copies per m3 (IQR: 0.4.103-9.103) in clinical areas to 9.7.103 (5.1.103-14.3.103) in the air of toilets or bathrooms. The protective equipment removal and patients rooms had high concentrations/titre of SARS-CoV-2 with aerosol size distributions that showed peaks in the <1 micrometers region, and staff offices in the >4 micrometers region. Conclusion In hospital, the air near and away from COVID-19 patients is frequently contaminated with SARS-CoV-2 RNA, with however, rare proofs of their viability. High viral loads found in toilet/bathrooms, staff and public hallways suggests to carefully consider these areas.

Aerosol transmission and COVID-19: overview

“…La majorité des études sur la transmission par aérosols (par méthodes moléculaires) a été réalisée à l'hôpital, au vu du nombre important de personnels de santé atteints de la maladie, du nombre de malades et des procédures de soins générant des aérosols [3]. Les professionnels de santé ont été particulièrement touchés par le SARS-CoV-2.…”

“…Même si Birgand [3] qualifie le SARS-CoV-2 de pathogène respiratoire à transmission « gouttelettes » mais « air » opportuniste, notamment dans les situations de hautes densités virales, la dichotomie aérosols/gouttelettes n'est pourtant que théorique et ne reflète pas la complexité de la réalité. Quelle que soit la taille des gouttelettes émises, il semble que la première phase de la maladie soit nasale, sans que les gouttelettes n'aient la nécessité d'aller loin dans l'appareil respiratoire.…”