key: cord-0773565-l1xia5lu
authors: Mouchtouri, Varvara A.; Koureas, Michalis; Kyritsi, Maria; Vontas, Alexandros; Kourentis, Leonidas; Sapounas, Spyros; Rigakos, George; Petinaki, Efthimia; Tsiodras, Sotirios; Hadjichristodoulou, Christos
title: Environmental contamination of SARS-CoV-2 on surfaces, air-conditioner and ventilation systems
date: 2020-08-13
journal: International Journal of Hygiene and Environmental Health
DOI: 10.1016/j.ijheh.2020.113599
sha: 9ac0d388f9cded2f249d3be8809126bfb24aa89d
doc_id: 773565
cord_uid: l1xia5lu

Abstract Background COVID-19 can be transmitted directly through respiratory droplets or indirectly through fomites. SARS-CoV-2 has been detected on various environmental surfaces, air samples and sewage in hospital and community settings. Methods Environmental samples were collected from a ferryboat during a COVID-19 ongoing outbreak investigation and a nursing home and from three COVID-19 isolation hospital wards and a long-term care facility where asymptomatic COVID-19 cases were isolated. Samples were tested by real-time reverse transcriptase–polymerase chain reaction. Results SARS-CoV-2 was detected on swab samples taken from surfaces of food preparation and service areas, hospital isolation wards, an air exhaust duct screen, air-conditioning filter, sewage treatment unit and air sample during investigations conducted in response to COVID-19 outbreaks on a ferryboat, nursing home, isolation facility and COVID-19 hospital wards. Discussion Food preparation areas and utensils can be contaminated during COVID-19 outbreaks. Respiratory droplets/nuclei from infected persons can be displaced by the air flow and deposited on surfaces. It can be assumed that in the same manner, air flow could transfer and deposit infected respiratory droplets/nuclei from infected persons to the mucous membranes of persons standing against the air flow direction.

Currently, it is accepted that COVID-19 can be transmitted directly through respiratory droplets or indirectly through fomites (Ong, Tan et al. 2020 , World Health Organization 2020 . Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been detected on various environmental surfaces, air samples and sewage in hospital and community settings (Moriarty, Plucinski et al. 2020 , Ong, Tan et al. 2020 , Wang, Feng et al. 2020 , Ye, Lin et al. 2020 .

We collected environmental samples from a ferryboat during a COVID-19 ongoing outbreak investigation with an attack rate of 31.3% (119/380 travelers), a nursing home (attack rate 9.8%, 12/122), three COVID-19 isolation hospital wards and hallways and a long-term care facility where 30 asymptomatic COVID-19 cases were isolated.

The World Health Organization guidelines were considered for sampling (World Health Organization 2020).

Air samples were collected with a portable air sampler (Sartorius Airport MD8) with air flow set to 50 L per minute and 10 minutes sampling time. Gelatin membrane filters of 80mm diameter (Sartorius 17528-80-ACD) were used. After sampling, filters were removed with sterilized forcep and placed in a 50ml conical tube filled with ¼ strength Ringer's solution.

Surface samples were collected by wearing sterile gloves as follows: swab was removed from the package, wet to the viral transport medium and then an area of 5 cm by 5 cm was swabbed by applying pressure with the swab on the surface and rotating the swab stick, then the swab was added to the vial that was placed in a self-sealing bag. The self-sealing bag was cleaned with J o u r n a l P r e -p r o o f 70% ethanol solution before placed to the transport container. Control samples were collected in the same way as the environmental samples from the potentially contaminated area, including opening the package and removing the swab from the tube, but without sampling any surfaces.

All samples were tested by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

Genetic material extraction was performed with the iPrep™ Purification Instrument (Invitrogen) using the iPrep™ PureLink® Virus Kit (Invitrogen). For the direct qualitative detection of SARS-CoV-2 RNA, multiplex specific real-time RT-PCR was performed with the RIDA®GENE SARS-CoV-2 RUO kit (R-Biopharm, Germany) in ABI STEP ONE real time system. For each sample a 10 -1 dilution was also analyzed and both samples and their dilutions were analyzed in duplicate. Table 1 presents the positive laboratory test results and Table 2 the negative laboratory results. SARS-CoV-2 RNA was detected on the air exhaust duct surface and screen of the ship hospital and cabins exhaust to open deck. Respiratory droplets/nuclei from infected persons were displaced and deposited on the air duct and screen of the ship air exhaust that was located in the open deck, three decks above the ship hospital examination area. Air from cabins and toilets of symptomatic and asymptomatic patients were directed towards the same air exhaust duct. SARS-CoV-2 RNA was detected on the filter of the air-conditioner device in the nursing home patient room. Both results demonstrate that respiratory droplets/nuclei from infected persons can be displaced by the air flow and deposited on surfaces (Lu, Gu et al. 2020 , Ong, Tan et al. 2020 . It can be assumed that in the same manner, air flow could transfer and deposit infected respiratory droplets/nuclei from infected persons to the mucous membranes of persons standing against the air flow direction (Lu, Gu et al. 2020 ).

The virus RNA was detected in one out of the 12 air samples collected. The positive air sample was collected at a height of approximately 0.8 meters and 2.5 meters away from a symptomatic patient not wearing a face mask. Symptomatic patients -if this is tolerated-could be advised to wear a face mask when a person is entering the isolation area. Equipment used for air sampling does not simulate human breathing patterns and therefore cannot ascertain the potential of airborne disease transmission.

SARS-CoV-2 RNA was detected on a food utensil during food preparation and on the bar counter where service of crew and passengers was taking place. It is possible that contamination of these surfaces occurred through the contaminated hands of food handlers either by respiratory excretions and/or faecal matter. The role of asymptomatic food handlers and the potential for transmission has not been studied yet. Food safety rules should be strictly applied including exclusion of symptomatic food handlers from working, strict personal hygiene, frequent cleaning and disinfection of food preparation areas (World Health Organization 2020). The use of face masks by food handlers handling ready-to-eat food (especially cold food) may be considered as a precautionary measure during the pandemic and until further evidence is available. Currently there is no evidence of such transmission events. SARS-CoV-2 RNA was detected in the sewage holding tank of the ferryboat. Occupational exposure, through direct contact with sewage or through inhalation of sewage aerosolized particles could occur and therefore personal protective equipment should be worn by ship crew and workers at the port waste reception facilities.

Our study is limited, by the testing of a limited number of samples. It was not possible to implement a consistent organized monitoring protocol to test hypotheses for the routes of transmission in the specific outbreaks context. Further studies could test samples by culture and J o u r n a l P r e -p r o o f even sequencing of clinical and environmental strains could be conducted, both for the phylogenetic comparison of the strains and in order to find potential virus variants (World Health Organization 2020).

SARS-CoV-2 RNA was detected on various surfaces in community settings where outbreaks have occurred and in the immediate environment of patients in hospital wards (Table 1) . We were not able to quantify or check virus viability, however, other studies have demonstrated that SARS-CoV-2 can persist on various types of surfaces (Kampf, Todt et al. 2020) . J o u r n a l P r e -p r o o f

Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents

COVID-19 Outbreak Associated with Air Conditioning in Restaurant

Public Health Responses to COVID-19 Outbreaks on Cruise Ships -Worldwide

Air, Surface Environmental, and Personal Protective Equipment Contamination by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From a Symptomatic Patient

SARS-CoV-2 RNA detection of hospital isolation wards hygiene monitoring during the Coronavirus Disease 2019 outbreak in a Chinese hospital

COVID-19 and food safety: guidance for food businesses. Interim guidance, WHO

Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations Scientific brief

Surface sampling of coronavirus disease (COVID-19): A practical "how to" protocol for health care and public health professionals