TABLE 4.
Positive SARS-CoV-2 air and no-touch surface sampling studies in health care settingsa
| Study setting | Design | Proportion of positive samples | Strengths (+) and limitations (−) |
|---|---|---|---|
| Published studies with negative viral cultures | |||
| Santarpia et al., 2020 (
103)
Nebraska, USA Low- and high-risk |
13 pts in isolation units Air sampling: 50 liters/min for 15 min (750 liters) and personal air sampler (4 liters/min) on HCWs No-touch: air handling grates and window ledges |
Air: 12/19 in rooms, 7/12 in hallway, 4/4 on personal sampler No-touch: 4/5 grates, 16/22 ledges |
(+) Evaluation of long-range (e.g., hallway) and short-range (e.g., personal air sampler) (+) Sample positivity linked to onset of Sx (+) Viral loads measured (−) Unknown particle sizes (−) Sampler positions unknown or suboptimal (e.g., risk of contamination by particles resuspended from the floor) |
| Zhou et al., 2020 (104)
ondon, UK Low- and high-risk (including ICU) |
5 hospitals (including GW, ICU, emergency department) Air sampling: 3 or 4 samplers collecting 1 m3 in pt, staff, and public areas |
Air: 2/31 confirmed positive in cohort ward and acute admission unit; 14/31 suspected positive | (+) Viral loads measured (+) Sample positivity linked to ward type (GW>ICU) and distance from pt (−) Lack of clinical data on pts (−) Air sampling during AGPs (−) Unknown particle sizes (−) Unknown sampling flow rate and duration |
| Binder et al., 2020 (105)
California, USA Assumed low-risk |
20 hospitalized pts Air sampling: 3.5 liters/min for 4 h (840 liters) in in high- and low-risk areas |
Air: 3/195 from 3 different pt rooms (particle sizes, <4 μm and >4 μm) | (+) Aerosol sizes and viral loads measured (−) Lack of clinical data and risk level (−) UV light disinfection (false negative) (−) 50% of pts at day 8 or more of infection |
| Published studies without viral cultures | |||
| Chia et al., 2020 (193)
Singapore Low- and high-risk (including ICU) |
5 pts in AIIRs Air sampling: in 3 GW rooms, 6 samplers at 3.5 liters/min for 4 h (5,040 liters) No-touch: exhaust vents in 4 GW rooms and 1 ICU room |
Air: 2/3 (particle sizes, >4 μm and 1–4 μm) No-touch: 3/5 |
(+) Aerosol sizes and viral loads measured (+) Sample positivity linked to Sx (4/5 pts symptomatic on day of sampling), onset of illness (wk 1) and viral load (+) No AGPs during sampling |
| Liu et al., 2020 (194)
Wuhan, China Low- and high-risk (including ICU) |
Tertiary hospital (severe cases) and make-shift center (mild cases) Air sampling: various sampling duration at 5 liters/min in pt, staff and public areas No-touch: ICU room corner |
Air: 19/33 (particle sizes, 0.25–1.0 μm and >2.5 μm) No-touch: 2/2 |
(+) Aerosol sizes and viral loads measured (+) Sample positivity linked to ventilation (e.g., high loads in mobile toilet) (−) Lack of clinical data on individual pts (−) Floor sampling (risk of contamination by resuspension of settled particles) |
| Ding et al., 2020 (152)
Nanjing, China Unknown risk level |
10 pts in COVID-19 hospital Air sampling: various devices from 10 liters/min for 30 min to 500 liters/min for 20 min; EBC and exhaled air samples No-touch: toilet and roof exhausts |
Air: 1/46 in corridor; 0/2 EBC, 0/2 exhaled air No-touch: 1/1 toilet, 0/5 roof |
(+) Detailed description of pt data and environment (including air flows) (+) Specific data on exhaled breath (+) Viral loads measured (+) Hypothesis on fecal origin of aerosols (−) Unknown particle size |
| Guo et al., 2020 (144)
Wuhan, China Low- and high-risk (including ICU) |
15 ICU pts and 24 GW pts Air sampling: 300 liters/min for 30 min (9,000 liters) near and far from pts (e.g., corridor) No-touch: air outlets |
Air: 14/40 in ICU, 2/16 in GW No-touch: 8/12 in ICU, 1/12 in GW |
(+) Viral loads measured (+) Sample positivity inversely correlated with distance from pt: positive up to 4 m away (−) Unknown particle sizes |
| Ong et al., 2020 (146)
Singapore Assumed low-risk |
3 symptomatic pts in AIIRS Air sampling: 5 liters/min for 4 h and 6 m3/h for 15 min (1,200–1,500 liters) No-touch: air outlet fan |
Air: 0/10 No-touch: 2/3 |
(+) Sample positivity correlated with clinical data and timing of cleaning (+) Viral loads measured (−) Air outlet fan close enough to coughing pt to be contaminated by droplets (195) |
| Ma et al., 2020 (153) Beijing, China Low- and high-risk (including ICU) |
Hospital and quarantine hotel Air sampling: 15 to 400 liters/min for 40 min (600–16,000 liters) Breath sampling from 49 pts: 300–500 μl of EBC No-touch: ventilation duct |
Air: 1/26 in unventilated hotel toilet EBC: 14/52 No-touch: 1/1 |
(+) Specific data on exhaled breath (+) Viral loads measured (+) Sample positivity linked to disease stage (−) Possible saliva contamination of EBC (196) (−) Possible contamination of ventilation duct (located beneath a pt bed) (−) Unknown particle sizes |
| Razzini et al., 2020 (197)
Milan, Italy High-risk (ICU) |
3 pts in a COVID-19 isolation ward Air sampling: 50 liters/min for 40 min (2 m3) in contaminated (pt) areas, semicontaminated and clean (staff) areas |
5 samples total: 100% positive in contaminated areas, 0% in semicontaminated and clean areas | (+) Viral loads measured (−) Unknown particle sizes (−) Lack of clinical data on pts (−) Unspecified no. of samples per area (−) High-risk setting only (2/3 pts intubated) |
| Kenarkoohi et al., 2020 (198)
Iran Low- and high-risk (including ICU) |
10–30 pts in different areas of a COVID-19 hospital Air sampling: 12 liters/min for 3 h (2,160 liters) in ICU, GW, and low-risk areas |
Air: 2/14 (in 2 ICU wards with 10 severely ill pts each) | (+) Viral loads measured (+) Detailed information on environment, pts and interventions (−) PM (particulate matter) sizes measured, but not viral aerosol sizes |
| Mouchtouri et al., 2020 (199)
Greece Low- and high-risk |
Hospital AIIR, long-term care isolation wards, nursing home Air sampling: 50 liters/min for 10 min (500 liters) |
Air: 1/12 (maskless hospitalized pt) No-touch: 1 (nursing home A/C filter) |
(+) Inclusion of long-term care facilities (−) Unknown particle concentration and sizes (−) Unknown total no. of pts and lack of clinical data on pts |
| Unpublished studies with positive viral cultures | |||
| Santarpia et al., 2020 (preprint) (106) Nebraska, USA Unknown risk level |
Air sampling: 6 samplers at 3.5 liters/min for 30 min (105 liters) | Air: 6/6 (particle size, <1 μm) | (+) Aerosol sizes and viral loads measured (+) Viral protein and RNA detection from culture (−) Absence of CT values (−) TCID50 value obtained in culture applied to initial air sample |
| Lednicky et al. (2020) (preprint) (107)
Florida, USA Low-risk |
2 pts in a designated COVID-19 ward Air sampling: 3 h |
Air: 4/4 | (+) Water vapor condensation sampling (+) Matching virus sequence with pt swab (−) Lack of symptom data on pts (−) Unknown flow rate of air sampling (−) Implausible viral loads (−) Unknown particle sizes |
a
AIIR, airborne infection isolation rooms; ICU, intensive care unit; GW, general ward; TCID50, 50% tissue culture infective dose; pt(s), patient(s); Sx, symptom(s); EBC, exhaled breath concentrate; IPC, infection prevention and control.