Severe acute respiratory coronavirus virus 2 (SARS-CoV-2) RNA and viable virus contamination of hospital emergency department surfaces and association with patient coronavirus disease 2019 (COVID-19) status and aerosol-generating procedures

TL;DR

This study found that hospital emergency department surfaces are often contaminated with SARS-CoV-2, especially in rooms where patients with COVID-19 did not undergo aerosol-generating procedures.

Contribution

The study identifies a link between patient COVID-19 status and surface contamination levels, independent of aerosol-generating procedures.

Findings

SARS-CoV-2 RNA contamination was most common in rooms of COVID-19 patients who did not undergo aerosol-generating procedures.

Emergency department surfaces are at high risk for SARS-CoV-2 contamination.

The presence of viable virus was confirmed on contaminated surfaces.

Abstract

Emergency departments are high-risk settings for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) surface contamination. Environmental surface samples were obtained in rooms with patients suspected of having COVID-19 who did or did not undergo aerosol-generating procedures (AGPs). SARS-CoV-2 RNA surface contamination was most frequent in rooms occupied by coronavirus disease 2019 (COVID-19) patients who received no AGPs.

Figures

A and B online).

Full text

The emergency department (ED) serves as the gateway for hospital admission for severe coronavirus disease 2019 (COVID-19). Many of these patients require respiratory aid via aerosol-generating procedures (AGPs), which can contaminate environmental surfaces through aerosol deposition. Severe acute respiratory coronavirus virus 2 (SARS-CoV-2) environmental contamination after procedures carries implications for transmission, and characterizing this contamination can guide infection prevention practices. We determined the occurrence and viability of SARS-CoV-2 on ED surfaces when COVID-19 patients did and did not receive AGPs.

Methods

Patients presenting to the Yale New Haven Hospital Adult ED, composed of 101 beds across 2 campuses, were evaluated for COVID-19. From January through December 2021, environmental swabs were collected from a convenience sample of rooms housing patients actively infected with or under investigation for COVID-19. Sampling was prioritized for rooms of patients receiving AGPs. AGPs were classified as endotracheal intubation or extubation, manual bag-valve-mask (BVM) ventilation, cardiopulmonary resuscitation, noninvasive positive-pressure ventilation (NPPV), high-flow oxygenation, bronchoscopy, and nebulizer therapy.^ 1 ^

From each room, 5 samples were collected while occupied by the patient or immediately following discharge or transfer, but prior to cleaning. Among these samples, 4 were from fixed surfaces, selected based on touch frequency and aerosol source proximity: high-touch surfaces within and farther than 2 m (6 feet) from the patient (bedrail, door handle, respectively), and low-touch surfaces within and farther than 2 m (6 feet) from the patient: vital signs monitor frame, air return vent (standard rooms) or procedure light (resuscitation rooms), respectively. A fifth sample was taken from the reusable AGP equipment or oxygen gauge behind the bed. Surface swabs underwent RNA extraction and RT-qPCR using N1 primers, and RNA copies were quantified via a standard curve using controls of known copy number. Positive samples were cultured using Vero E6 cells and were examined for cytopathic effect. Severity was classified using a previously validated COVID-19 ordinal severity index.^ 2 ^ Differences between AGP and non-AGP room SARS-CoV-2 RNA contamination frequency were analyzed with the Fisher exact test and concentrations were analyzed with the Kruskal-Wallis test. Additional methods are in the Supplementary Material (online).

Results

Sample collection yielded 1,010 environmental specimens from 202 rooms. Room types included resuscitation bays (n = 69, 34.2%), airborne-infection isolation rooms (n = 56, 27.7%), and standard rooms (n = 77, 38.1%). AGPs were performed in 157 rooms (77.7%), and included intubation (n = 52), NPPV (n = 47 BiPAP and 2 CPAP), high-flow oxygenation (n = 34), nebulizer therapy (n = 13), and BVM ventilation (n = 1), or multiple AGPs (n = 8). Of 202 rooms, 87 housed SARS-CoV-2–positive patients (43.1%), approximately half of whom received AGPs (n = 42, 48.3%). These included high-flow oxygenation (n = 28), NPPV (n = 4), nebulizers (n = 4), intubation (n = 4), or multiple (n = 2).

In total, 36 swabs (3.6%, n = 1,010) from 29 rooms (14.4%, n = 202) were positive for SARS-CoV-2 RNA (Table 1). Of 87 COVID-19 patient rooms, 19 (21.8%) had SARS-CoV-2 RNA on at least 1 surface, including 13 rooms (28.9%, n = 45) where AGPs were not performed and 6 rooms (14.3%, n = 42) where AGPs were performed (P = .123). Patients spent more time in the room prior to environmental swab collection when surfaces were SARS-CoV-2 RNA-positive (mean, 295.4 minutes; n = 19) versus negative (mean, 223.8 minutes; n = 68), but this was not statistically significant (P = .213). SARS-CoV-2 RNA was detected in 10 rooms (8.7%, n = 115) occupied by SARS-CoV-2–negative patients. The mean estimated concentration of SARS-CoV-2 RNA on contaminated surfaces was 24.1 (median, 20.2) copies per 100 cm^2^ in rooms housing SARS-CoV-2–negative patients, 52.1 (median, 48.1) copies per 100 cm^2^ in rooms housing COVID-19 patients who underwent AGPs, and 147.6 (median, 43.7) copies per 100 cm^2^ in rooms housing COVID-19 patients who did not undergo an AGP (P = .239).

Table 1.Percentage of Rooms and Surface Swabs Testing Positive for SARS-CoV-2 RNA or Infectious Virus by RT-qPCR or CultureCOVID-19 StatusAerosol-Generating Procedure (AGP)Rooms Sampled,No.Rooms (%) Positive for SARS-CoV-2 RNA,No. (%)Swabs Collected, No.Swabs Positive for SARS-CoV-2 RNA,No. (%)Average SARS-CoV-2 RNA Copies per 100 cm^2^ Swabbed Surface Area^ a ^ Swabs Positive by Viral Tissue Culture, No.PositiveYes426 (14.3)2108 (3.8)52.10PositiveNo4513 (28.9)22516 (7.1)147.61NegativeYes11510 (8.7)57512 (2.1)24.10Total20229 (14.4)1,01036 (3.6) 1 Note. RT-qPCR, reverse-transcription quantitative polymerase chain reaction. a Mean copies, as determined by RT-qPCR curve determined from known quantities of PCR.

Of the 6 SARS-CoV-2 RNA-contaminated rooms of SARS-CoV-2–positive patients where AGPs occurred, high-flow oxygenation occurred in 5 rooms (n = 28), and nebulizer therapy occurred in 1 room (n = 4). No SARS-CoV-2–positive patient room surfaces were contaminated after intubation (n = 4) or NPPV (n = 4).

SARS-CoV-2 RNA was most frequently detected on air-duct return vents (13 of 133, 9.8%), followed by bedrails (10 of 202, 5.0%), reusable equipment (4 of 202, 2.0%), monitors (4 of 202, 2.0%), door handles (3 of 202, 1.5%), and procedure lights (2 of 69, 2.9%) (Table 2). SARS-CoV-2 RNA contamination ranged from 5–687 copies per 100 cm^2^ on vents, 6–74 copies per 100 cm^2^ on bedrails, 32–39 copies per 100 cm^2^ on door handles, 16–65 copies/100 cm^2^ on reusable equipment, and 22–504 copies per 100 cm^2^ on the monitor frame (Table 2 and Supplementary Table 1 online). Most contaminated rooms had only 1 SARS-CoV-2–positive surface; however, 6 rooms had multiple positive surfaces. A higher percentage of nonresuscitation rooms were positive (17.9%, n = 24 of 134) than resuscitation rooms (7.4%, n = 5 of 68; P = .055).

Table 2.Emergency Department Room Surfaces Positive for SARS-CoV-2 ContaminationRNA Copies/cm^2^ SurfaceSurface Area Sampled (cm^2^)Samples Collected, No.Positive Surface Swabs, No. (%)TotalMeanRangeIQRHigh touch, near patient (< 2 m): bedrails12920210 (5.0)84.815.94.7–538.18.7–70.2High touch, distant from patient (>2 m): door handle652023 (1.5)35.936.132.3–39.434.2–37.7Low touch, distant from patient (>2 m):Air return ventResuscitation room procedure lights152321336913 (9.8)2 (2.9)91.131.028.631.05.0–686.611.9–50.19.6–71.721.4–40.5Low touch, near patient (<2 m): vital signs monitor frame1942024 (2.0)178.092.522.2–504.733.4–237.1 Reusable AGP equipment Glidescope15540 (0.0)…Noninvasive positive pressure ventilation control screen frame (BiPAP; CPAP)226530 (0.0)…High-flow oxygen control219361 (2.8)15.915.9……Oxygen gauge (swabbed for nebulizer treatments and when no AGP‡ was administered)97561 (1.8)64.864.8……Mechanical ventilation control screen frame226492 (4.1)36.336.325.8–46.831.0–41.6Note. BiPAP, bilevel positive airway pressure; CPAP, continuous positive airway pressure; AGP, aerosol-generating procedure.

Of the 36 SARS-CoV-2 RNA-positive samples (bedrail, non-AGP COVID-19 patient), 1 sample was positive by viral tissue culture, exhibiting extensive cytopathic effect. SARS-CoV-2 RNA copy number in pre- and post-incubation tissue culture medium went from undetectable to 3.5 × 10^8^ copies, respectively.

COVID-19 patients occupied 13 of the 202 sampled rooms (6.4%) immediately preceding the occupant present during sampling. One of these rooms had an equipment surface positive for SARS-CoV-2 RNA while occupied by the subsequent SARS-CoV-2–negative patient.

The median severity of patient illness on arrival was 5.0 (IQR, 2.5–6.0) in rooms with SARS-CoV-2 contamination compared to 6.0 (IQR, 4.75–6.0) in rooms without contamination (P = .259). The median number of days from symptom onset to ED presentation was 4.0 (IQR, 3.0–7.0) in rooms with detectable SARS-CoV-2 contamination compared to 7.0 (IQR, 3.0–8.5) in rooms without (P = .507) (Supplementary Fig. 1A and B online).

Discussion

SARS-CoV-2 RNA contamination was detected on at least 1 surface in >20% of rooms housing patients with COVID-19. Surface contamination was detected more frequently in rooms of COVID-19 patients who did not have an AGP. We suspect that this finding is due to the natural progression of COVID-19 in which viral loads peak around symptom onset, and more severe disease occurs later in the hyperinflammatory phase of illness when viral load is diminished.^ 3,4 ^ This carries infection control implications; mitigating transmission earlier in the disease course when viral transmission potential is greatest may be more impactful, regardless of aerosol deposition.

We observed SARS-CoV-2 contamination in 9% of SARS-CoV-2–negative patient rooms. Given the rapid turnover of ED rooms, prior patients could have contributed to contamination, especially on air-return vents because these are not disinfected between patients. This finding also highlights the ability of upward airflow, even in rooms maintained without negative pressure, to move SARS-CoV-2 aerosols to surfaces unlikely to be implicated in viral transmission.

One sample grew SARS-CoV-2 in tissue culture. Infectious virus has rarely been recovered from hospital surfaces, and positive surfaces are typically within close range of the patient.^ 5–7 ^ SARS-CoV-2 remains viable on surfaces up to 21 days, with a half-life of ∼2–5 days,^ 8 ^ whereas SARS-CoV-2 RNA exhibits a 1-log reduction over the same period.^ 9 ^ Therefore, failure to detect viable virus in more samples with high viral concentrations is not unexpected and supports the evidence of a minimal role of surface and fomite transmission in SARS-CoV-2 spread.^ 10 ^ Study limitations include observations at a single emergency department and limited comparisons between AGPs due to small sample sizes. It is unclear whether these findings would be replicated in asymptomatic COVID-19 populations.