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Airborne SARS-CoV-2 surveillance in hospital environment using high-flowrate air samplers and its comparison to surface sampling.

ABSTRACT: Reliable methods to detect the presence of SARS-CoV-2 at venues where people gather are essential for epidemiological surveillance to guide public policy. Communal screening of air in a highly crowded space has the potential to provide early warning on the presence and potential transmission of SARS-CoV-2 as suggested by studies early in the epidemic. As hospitals and public facilities apply varying degrees of restrictions and regulations, it is important to provide multiple methodological options to enable environmental SARS-CoV-2 surveillance under different conditions. This study assessed the feasibility of using high-flowrate air samplers combined with RNA extraction kit designed for environmental sample to perform airborne SARS-CoV-2 surveillance in hospital setting, tested by RT-qPCR. The success rate of the air samples in detecting SARS-CoV-2 was then compared with surface swab samples collected in the same proximity. Additionally, positive RT-qPCR samples underwent viral culture to assess the viability of the sampled SARS-CoV-2. The study was performed in inpatient ward environments of a quaternary care university teaching hospital in Singapore housing active COVID-19 patients within the period of February to May 2020. Two types of wards were tested, naturally ventilated open-cohort ward and mechanically ventilated isolation ward. Distances between the site of air sampling and the patient cluster in the investigated wards were also recorded. No successful detection of airborne SARS-CoV-2 was recorded when 50 L/min air samplers were used. Upon increasing the sampling flowrate to 150 L/min, our results showed a high success rate in detecting the presence of SARS-CoV-2 from the air samples (72%) compared to the surface swab samples (9.6%). The positive detection rate of the air samples along with the corresponding viral load could be associated with the distance between sampling site and patient. The furthest distance from patient with PCR-positive air samples was 5.5 m. The airborne SARS-CoV-2 detection was comparable between the two types of wards with 60%-87.5% success rate. High prevalence of the virus was found in toilet areas, both on surfaces and in air. Finally, no successful culture attempt was recorded from the environmental air or surface samples.

SUBMITTER: Ang AX

PROVIDER: S-EPMC8653264 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundAn outbreak of monkeypox virus infections in non-endemic countries was recognised on May 12, 2022. As of September 29, more than 67 000 infections have been reported globally, with more than 3400 confirmed cases in the UK by September 26. Monkeypox virus is believed to be predominantly transmitted through direct contact with lesions or infected body fluids, with possible involvement of fomites and large respiratory droplets. A case of monkeypox in a health-care worker in the UK in 2018 was suspected to be due to virus exposure while changing bedding. We aimed to measure the extent of environmental contamination in the isolation rooms of patients with symptomatic monkeypox.MethodsWe investigated environmental contamination with monkeypox virus from infected patients admitted to isolation rooms at the Royal Free Hospital (London, UK) between May 24 and June 17, 2022. Surface swabs of high-touch areas in five isolation rooms, of the personal protective equipment (PPE) of health-care workers in doffing areas in three rooms, and from air samples collected before and during bedding changes in five rooms were analysed using quantitative PCR to assess monkeypox virus contamination levels. Virus isolation was performed to confirm presence of infectious virus in selected positive samples.FindingsWe identified widespread surface contamination (56 [93%] of 60 samples were positive) in occupied patient rooms (monkeypox DNA cycle threshold [Ct] values 24·7-37·4), on health-care worker PPE after use (Ct 26·1-35·6), and in PPE doffing areas (Ct 26·3-36·8). Of 20 air samples taken, five (25%) were positive. Three (75%) of four air samples collected before and during a bedding change in one patient's room were positive (Ct 32·7-36·2). Replication-competent virus was identified in two (50%) of four samples selected for viral isolation, including from air samples collected during bedding change.InterpretationThese data show contamination in isolation facilities and potential for suspension of monkeypox virus into the air during specific activities. PPE contamination was observed after clinical contact and changing of bedding. Contamination of hard surfaces in doffing areas supports the importance of cleaning protocols, PPE use, and doffing procedures.FundingNone.

Project description:BackgroundThe mechanism for spread of SARS-CoV-2 has been attributed to large particles produced by coughing and sneezing. There is controversy whether smaller airborne particles may transport SARS-CoV-2. Smaller particles, particularly fine particulate matter (≤ 2.5 µm in diameter), can remain airborne for longer periods than larger particles and after inhalation will penetrate deeply into the lungs. Little is known about the size distribution and location of airborne SARS-CoV-2 RNA.MethodsAs a measure of hospital-related exposure, air samples of three particle sizes (> 10.0 µm, 10.0-2.5 µm, and ≤ 2.5 µm) were collected in a Boston, Massachusetts (USA) hospital from April to May 2020 (N = 90 size-fractionated samples). Locations included outside negative-pressure COVID-19 wards, a hospital ward not directly involved in COVID-19 patient care, and the emergency department.ResultsSARS-CoV-2 RNA was present in 9% of samples and in all size fractions at concentrations of 5 to 51 copies m-3. Locations outside COVID-19 wards had the fewest positive samples. A non-COVID-19 ward had the highest number of positive samples, likely reflecting staff congregation. The probability of a positive sample was positively associated (r = 0.95, p < 0.01) with the number of COVID-19 patients in the hospital. The number of COVID-19 patients in the hospital was positively associated (r = 0.99, p < 0.01) with the number of new daily cases in Massachusetts.ConclusionsMore frequent detection of positive samples in non-COVID-19 than COVID-19 hospital areas indicates effectiveness of COVID-ward hospital controls in controlling air concentrations and suggests the potential for disease spread in areas without the strictest precautions. The positive associations regarding the probability of a positive sample, COVID-19 cases in the hospital, and cases in Massachusetts suggests that hospital air sample positivity was related to community burden. SARS-CoV-2 RNA with fine particulate matter supports the possibility of airborne transmission over distances greater than six feet. The findings support guidelines that limit exposure to airborne particles including fine particles capable of longer distance transport and greater lung penetration.

Project description:The shedding of pathogens by infected humans enables the use of sewage monitoring to conduct wastewater-based epidemiology (WBE). Although most WBE studies use data from large sewage treatment plants, timely data from smaller catchments are needed for targeted public health action. Traditional sampling methods, like autosamplers or grab sampling, are not conducive to quick ad hoc deployments and high-resolution monitoring at these smaller scales. This study develops and validates a cheap and easily deployable passive sampler unit, made from readily available consumables, with relevance to the COVID-19 pandemic but with broader use for WBE. We provide the first evidence that passive samplers can be used to detect SARS-CoV-2 in wastewater from populations with low prevalence of active COVID-19 infections (0.034 to 0.34 per 10,000), demonstrating their ability for early detection of infections at three different scales (lot, suburb, and city). A side by side evaluation of passive samplers (n = 245) and traditionally collected wastewater samples (n = 183) verified that the passive samplers were sensitive at detecting SARS-CoV-2 in wastewater. On all 33 days where we directly compared traditional and passive sampling techniques, at least one passive sampler was positive when the average SARS-CoV-2 concentration in the wastewater equaled or exceeded the quantification limit of 1.8 gene copies per mL (n = 7). Moreover, on 13 occasions where wastewater SARS-CoV-2 concentrations were less than 1.8 gene copies per mL, one or more passive samplers were positive. Finally, there was a statistically significant (p < 0.001) positive relationship between the concentrations of SARS-CoV-2 in wastewater and the levels found on the passive samplers, indicating that with further evaluation, these devices could yield semi-quantitative results in the future. Passive samplers have the potential for wide use in WBE with attractive feasibility attributes of cost, ease of deployment at small-scale locations, and continuous sampling of the wastewater. Further research will focus on the optimization of laboratory methods including elution and extraction and continued parallel deployment and evaluations in a variety of settings to inform optimal use in wastewater surveillance.

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Airborne SARS-CoV-2 surveillance in hospital environment using high-flowrate air samplers and its comparison to surface sampling.

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