Table I.

Main characteristics of included studies that assessed fomite transmission of SARS-CoV-2

Study ID	Country	Setting dates	Types of participants	Sources of fomites	Test used to detect SARS-CoV-2	Notes
Adenaiye 2021 [11]	USA	University campus May 2020 to Apr 2021	Participants with active SARS-CoV-2 infection (N = 49)	Mobile phones.	qRT–PCR	Used data from seronegative cases. The limit of detection (LOD) was 75 copies/sample.
Ahn 2020 [12]	South Korea	Tertiary care hospital Mar 2020	Three lab-confirmed COVID-19 patients who required high-flow oxygen therapy or mechanical ventilation.	Bedside tables, blood pressure cuffs, pillows, bedsheets, nasal prongs, outside surface of the ventilator circuit, tubing, masks, telephones, thermometers, keyboards, and fixed structures in the room (such as the doorknob, bedrails, floor, walls, window, and faucet handles), and grills of the ventilation exits in the ceiling.	rRT–PCR	Patient 1 was a 71-year-old man who presented with severe pneumonia. He was started on mechanical ventilation on hospital admission, 15 days after the onset of symptoms. Patient 2 was a 67-year-old woman with rapidly progressing pneumonia who was started on mechanical ventilation on hospital day 2, five days after the onset of symptoms. Patient 3 was a 44-year-old man with underlying terminal lung cancer and progressive pneumonia caused by SARS-CoV-2; high-flow oxygen therapy via high-flow nasal cannula at 60 L/min was started from hospital day 3, five days from the onset of symptoms. A positive test result was defined as CT ≤35 for the RdRp and E genes.
Alvis-Chirinos 2021 [13]	Peru	Public spaces Nov and Dec 2020	Food surfaces and inert surfaces in three districts.	Foods: bulk rice, avocado, banana, mango, lemon, tomato, lettuce, potato, cheese, chicken. Inert surfaces: handrails, seats, counter, touch screen, shopping cart handle, vending stand, and ATMs.	Nucleic acid detection kit	Three districts with the highest number of COVID-19 cases were selected. Public spaces: market, supermarket, public transport bus, train, and bank agency. CT >39 for the ORF1ab gene considered negative.
Ang 2021 [14]	Singapore	Quaternary care university teaching hospital Feb–May 2020	Active COVID-19 patients.	Patient care and staff area: floor, table, bed handrail, nurse call button, cell phone, the sink, and door handles. Toilet area: door handle, the sink, toilet ledge, toilet bowl, and the flush button.	RT–qPCR	The presence of SARS-CoV-2 was detected by RT–qPCR of the E-gene and N-gene. Positive control CT values ranged between 30.0 and 30.8 for the 1 pfu-positive control and 33.8–35.1 for the 0.1 pfu-positive control. All patients involved during the study; however, could be considered as mildly symptomatic without significant hypoxia or need for oxygen.
Bartlett 2021 [15]	USA	University hospital Apr 16th–30th, 2020	HCPs (N = 42) directly caring for non-ICU patients infected with SARS-CoV-2.	1. High-touch surface areas outside the rooms of COVID-19 patients: donning/doffing stations, doorknobs, door thresholds, and shared workstations (mouse and keyboard). 2. High-touch surface areas in the emergency room and other COVID-19 wards: door handles and shared workstations).	RT–qPCR	Spike assay was evaluated using 10-fold serial dilutions of SARS-CoV-2 RNA.
Ben-Shmuel 2020 [16]	Israel	COVID-19 isolation units in two hospitals and one quarantine facility	Patients with COVID-19.	‘Mild COVID-19: floor, bedrails, bedside table, faucet handle, mobile phones, eyeglasses, patient's walker, air sampling filter Severe COVID-19: bedrails, faucet handle, ventilator, staff computer mouse, staff mobile phone, bedside table, trash bin top, bench top, air sampling filter Patient's toilets: toilet seat, handle grip, door handle Nurse station: floor, bench top, computer mouse, staff mobile phone, glucometer, electric thermometer, blood pressure cuff, air sampling filter Doffing area: floor, door handle, trash bin top, air sampling filter’	rRT–PCR	Mild COVID-19 patients required no ventilation. Patients stayed in private rooms either alone or as a family but were free to move around the hotel and socialize in public spaces.
Binder 2020 [17]	USA	University hospital Apr–May 2020	Hospitalized COVID-19 patients (N = 20) and their close contacts (N = 6).	1. Toilet seat and interior of toilet bowl, TV remote control, cell phone, bedrailings and bed tray. 2. Hospital ward break room and head nurse and physician workstation.	RT–PCR	For quality control, all RT–PCR assays were run twice; positive and negative controls used.
Coil 2021 [18]	USA	Academic medical centre Apr–Aug 2020	Active COVID-19 hospitalized in three ICU and two medical wards.	Doffing station, hand sanitizers, nightstand, computer station, door handle, ventilator, endotracheal tube straps, floor, intravenous pump, arterial line plunger, window, soiled linen, telemetry screen, heating, ventilation and air-conditioning (HVAC) system.	qRT–PCR	Air pressure in the HVAC system was temporarily reduced during sampling. Samples were collected both from the floor with some COVID-19 patients, as well as from another floor with no known COVID-19 patients.
Colaneri 2020 [19]	Italy	Emergency unit and the sub-intensive care ward	Area where febrile patients with respiratory symptoms were evaluated, and an infectious disease sub-intensive care ward that allows advanced respiratory care.	Pre-intensive care ward Ward and buffer zone: exit buffer zone (1); computer keyboards in staff lounge (1). Rooms of patients A and B with CPAP helmet: bedrails (1), infusion pump (1), multi-parameter monitor (1), nurse buzzer (1), CPAP helmet, exterior surface (1), table (1) room of patient C in high-flow oxygen therapy: bedrails (1), multi-parameter monitor (1), infusion pump (1), table (1). Staff PPE: liquid-repelling gowns after 1 h of use (1), face shield and eye goggles (1), woven gown worn over liquid-repelling gown after 1 h of use (1), staff gloves, internal pair (1). Infectious disease emergency unit Ward: computer keyboards in triage and examination rooms (1), telephones (1), doorknobs and water taps in patient toilets (1). Staff equipment: portable X-ray machine (1), ECG machine (1), Medication cart (1). Patient rooms: beds (1), bed of patient with CPAP helmet (1). Staff equipment: liquid-repelling gowns, after 7 h of use (1), face shields (1), nurse gloves, internal pair gloves (1), staff mobile phone (1).	rRT–PCR	Real-time RT–PCR targeting RNA-dependent RNA polymerase and E genes.
da Silva 2021 [20]	Brazil	Public areas Feb 2021	N/A	Transport terminals: (i) toilets; (ii) benches; (iii) public bike station; (iv) outdoor gym; (v) fresh green coconut; (vi) handrails; (vii) faucet; (viii) traffic light button; (ix) bus stop; (x) resting area. Healthcare units: (i) playground; (ii) recreation area; (iii) outdoor gym; (iv) toilet; (v) handrail; (vi) bus stop; (vii) public bike station; (viii) traffic light button; (ix) coffee shop; (x) faucet. Beach areas: (i) toilet; (ii) restaurant; (iii) handrail; (iv) resting area. Public parks: (i) playground; (ii) recreation area; (iii) outdoor gym; (iv) toilet; (v) handrail; (vi) bus stop; (vii) public bike station; (viii) traffic light button; (ix) coffee shop; (x) faucet. Supply centre: (i) toilet; (ii) restaurant; (iii) handrail; (iv) resting area. Public markets: (i) principal entrance; (ii) side entrance; (iii) public market access; (iv) toilet; (v) kiosk; (vi) store; (vii) food hall; (viii) traffic light button; (ix) faucet; (x) resting area; (xi) outside area.	RT–qPCR	Samples collected from highly frequented areas. Samples were considered positive when they presented amplification for N1 target, CT value of <40.
Dumont-Leblond 2021 [21]	Canada	Long-term care facilities Spring 2020	Residents and HCWs.	Shelving units, door frames.	RT–qPCR	Only RT–qPCR results under 40 CT were considered positive.
Espinoza 2021 [22]	Brazil	COVID-19 ICU of a teaching hospital	HCWs in close contact with adults infected with COVID-19.	Mobile phones of HCWs.	RT–PCR	Amplification was carried out using the Roche Light Cycler® 96 System. A sample was considered positive when at least one of the target genes (S and E) was detected.
Kowta 2021 [23]	Canada	Six acute care hospitals March–May 2020	Consecutive patients (N = 78) hospitalized on any ward with lab-confirmed COVID-19.	(1) Bathroom doorknob, (2) phone (all surfaces of the patient's phone and room phone), (3) overbed table and chair (pooled), (4) bed (bedrail and pillow) and light switch or pullcord in patient's bedspace (pooled), and (5) toilet and sink faucet handles.	RT–PCR	Two separate gene targets were used for detection of SARS-CoV-2, the 5ʹ untranslated region (UTR) and the envelope (E) gene. Samples with CT <40 in both UTR and E genes were considered positive. In logistic regression analysis, the likelihood of positive viral culture was significantly more if the fomite sample was collected within 7 days of symptom onset (P = 0.02).
Lin 2021 [24]	Canada	Four hospitals Apr 2020 to Mar 2021	Patients with COVID-19 (N = 75).	Facial tissues, nasal prongs, call bells/cell phones, dentures, and sputum deposits	rRT–PCR	Samples were considered positive when E gene CT value was <35. For community participants, the responsible Medical Officer of Health Alberta Health Services (AHS) Public Health (PH) in Calgary provided a list of people who had tested positive for COVID-19 confirmed by RT–PCR and were approached by telephone to participate in the study in their community setting. Hand samples were collected post handshake from each hand in a patient who was 1 day from symptom onset and had a cough.
Ma 2021 [25]	China	Dock, Shandong Province Sep 2020	Two asymptomatic infected dock workers.	Cold chain products (frozen cods): outer packaging.	rRT–PCR	The two infected dock workers only unloaded frozen cod from abroad. Both had no history of living in high-risk areas in China and had no contact with patients from high-risk areas or patients with unexplained fever. There were no imported cases in their communities for 55 days, and neither dock worker had contact history with people returning from overseas. rRT–PCR CT value of ORF1ab and N gene target ≤40 was positive.
Ma 2021a [26]	China	Dock, Liaoning Province Jun–Jul 2020	Dock workers (N = 63) in contact with cold-chain products.	Operating table, floor, tools, sinks, sewers, and other environmental locations.	RT–qPCR Nucleic acid	Samples were taken from the food processing area of the dock company. A TaqMan probe-based kit was designed to detect the ORF1ab and N genes of COVID-19 virus in one reaction.
Marcenac 2021 [27]	USA	Households Mar 30th to Apr 25th, 2020	Index patient in a household living with ≥1 person, and positive for SARS-CoV-2 on a nasopharyngeal swab collected ≤10 days prior to enrolment.	Light switches (2 samples/household), toilet handles (1/household), bathroom sink handles (1/household), pillows or nightstands of index cases (1/household), pillows or nightstands of contacts (2/household), and refrigerator handles (1/household).	RT–PCR	Remaining surfaces were selected by requesting that household members identify frequently touched surfaces in their respective household, which at times were additional surfaces of pre-assigned types (e.g. bathroom sink handles).
Nannu Shankar 2021 [28]	USA	Residential rooms of two adults with COVID-19 Sep 2020	Two adults with COVID-19.	High-touch surface areas: Volunteer A: mobile phone, a laptop computer touch pad, and the left elbow. Volunteer B: mobile phone, room doorknob.	rRT–PCR	rRT–PCR tests were performed in a BioRad CFX96 Touch Real-Time PCR detection system using the SARS-CoV-2 N-gene detection primers and probe and rRT–qPCR parameters.
Newey 2021 [29]	USA	Near the campus of a university	N/A	1. Cash from university vault: comprises currency from university-based stores, restaurants, dormitories and vending machines 2. Fresh samples of cash and/or coins were obtained from local restaurants.	LAMP assays
Oksanen 2021 [30]	Finland	COVID-19 ward, home July 2020–Mar 2021	Unvaccinated participants with RT–PCR-confirmed symptomatic COVID-19 infection (N = 31).	High-touch surfaces: bed remote, cellphone, drinking glass, computer, door handle. Low-touch surfaces: hospital equipment, floor, table, bedrail, airvent. Toilet surfaces: toilet seat, toilet flush button, toilet tap, toilet bowl. Other surfaces: staff PPE.	RT–PCR	31 collections were performed, 24 of them on the cohort COVID-19 ward and 7 in patients' homes in normal rooms where the patients spent time during illness. PCR was positive if CT value <38. RNA extracted from the Fin/20 strain culture was used as a positive control and nuclease-free water as a negative control.
Rajendiran 2021 [31]	Malaysia	ICU and general wards Mar 25th to Apr 17th, 2020	COVID-19 patients hospitalized in ICU and general wards.	High-touch surface areas: 1. Patient's cubicle or room (doorknob, bedrail, pillowcase, side table, cardiac table, floor at 1 m from patient's bed, ventilation outlet or window, blood pressure cuff, oximeter). 2. Areas in toilet (sink and toilet bowl) of general wards. 3. ICU: patient's cubicle (doorknob, bedrail, bedsheet, side table, floor 1 m from patient's bed, ventilation outlet, intravenous drip stand) and staff area (oximeter, monitor, phone, keyboard, mouse, soles of medical staff).	RT–PCR
Winslow 2021 [32]	UK	University hospital	30 hospitalized patients with COVID-19 requiring supplemental oxygen.	Floor, table, high-object surface.	RT–qPCR	A sample was defined as positive for viral RNA if both E and ORF1a RT–qPCR assays gave CT <45.
Zhou 2020 [33]	UK	Teaching hospital Apr 2020	Adults with COVID-19.	High-touch surfaces: bedrails, blood pressure monitors, ward telephones, computer keyboards, clinical equipment (syringe pumps, urinary catheters), hand-cleaning facilities (hand-washing basins, alcohol gel dispensers).	RT–qPCR	SARS-CoV-2 viral RNA was detected using AgPath-ID. One-step RT–PCR reagents with specific primers and probes targeting the envelope (E) gene. Samples were defined as positive if both duplicates had CT <40.4

ATM, automated teller machine; rRT–PCR, real-time reverse transcription–polymerase chain reaction; q, quantitative; LAMP; loop-mediated isothermal amplification; ICU, intensive care unit.