Investigation of nosocomial SARS-CoV-2 transmission from two patients to healthcare workers identifies close contact but not airborne transmission events

Bays, Derek; Nguyen, Mimi; Cohen, Stuart H.; Waldman, Sarah; Martin, Carla S.; Thompson, George R.; Sandrock, Christian; Tourtellotte, Joel; Pugashetti, Janelle Vu; Phan, Chia Wei; Nguyen, Hien; Warner, Gregory Y.; Penn, Bennett H.

doi:10.1017/ice.2020.321

Cited by 23 publications

(22 citation statements)

References 22 publications

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“…For example, in a study of two severely ill COVID-19 patients who were not initially isolated, contact tracing identified 421 HCWs, of whom only 8 tested positive (41). All infected HCWs had close and prolonged contact without wearing the mask or ocular protection and had been present during AGPs.…”

Section: Trials Comparing Masks and Respirators In Health Care Settingsmentioning

confidence: 99%

“…The vast majority of epidemiological studies that analyze SARS-CoV-2 outbreak patterns (case identification, contact tracing, epidemiological curves, and basic reproduction number or R0 estimates), undertaken in a variety of contexts, including health care facilities (41)(42)(43)(44)(45), homes (56), churches (57), fitness facilities (58), call centers (59), airplanes (60), and company conferences and tour groups (61), are in agreement: contact and droplets were the probable modes of transmission. Rather than long-range propagation and frequent mass outbreaks typical of airborne patterns, the distribution of infected individuals was strongly correlated with close encounters and secondary attack rates were estimated be very low, around 5% (62).…”

Section: Epidemiological Studies On Transmissionmentioning

confidence: 99%

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SARS-CoV-2 and Health Care Worker Protection in Low-Risk Settings: a Review of Modes of Transmission and a Novel Airborne Model Involving Inhalable Particles

Zhang

Duchaine

2020

Clin Microbiol Rev

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SUMMARY Since the beginning of the COVID-19 pandemic, there has been intense debate over SARS-CoV-2’s mode of transmission and appropriate personal protective equipment for health care workers in low-risk settings. The objective of this review is to identify and appraise the available evidence (clinical trials and laboratory studies on masks and respirators, epidemiological studies, and air sampling studies), clarify key concepts and necessary conditions for airborne transmission, and shed light on knowledge gaps in the field. We find that, except for aerosol-generating procedures, the overall data in support of airborne transmission—taken in its traditional definition (long-distance and respirable aerosols)—are weak, based predominantly on indirect and experimental rather than clinical or epidemiological evidence. Consequently, we propose a revised and broader definition of “airborne,” going beyond the current droplet and aerosol dichotomy and involving short-range inhalable particles, supported by data targeting the nose as the main viral receptor site. This new model better explains clinical observations, especially in the context of close and prolonged contacts between health care workers and patients, and reconciles seemingly contradictory data in the SARS-CoV-2 literature. The model also carries important implications for personal protective equipment and environmental controls, such as ventilation, in health care settings. However, further studies, especially clinical trials, are needed to complete the picture.

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Section: Trials Comparing Masks and Respirators In Health Care Settingsmentioning

confidence: 99%

Section: Epidemiological Studies On Transmissionmentioning

confidence: 99%

SARS-CoV-2 and Health Care Worker Protection in Low-Risk Settings: a Review of Modes of Transmission and a Novel Airborne Model Involving Inhalable Particles

Zhang

Duchaine

2020

Clin Microbiol Rev

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“…There is a growing international literature on nosocomial SARS-CoV-2 infection, from single ward or department reports, 15-23 to hospital-wide studies, 24-26 but only one (from Malta) based on limited national surveillance data. 27 The lull between phases of the pandemic in Europe has allowed prospective studies to be planned, but these have yet to report.…”

Section: Discussionmentioning

confidence: 99%

Healthcare-associated COVID-19 in England: a national data linkage study

Bhattacharya¹,

Collin²,

Stimson³

et al. 2021

Preprint

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Objectives: Nosocomial transmission was an important aspect of SARS-CoV-1 and MERS-CoV outbreaks. Healthcare-associated SARS-CoV-2 infection has been reported in single and multi-site hospital-based studies in England, but not nationally. Methods: Admission records for all hospitals in England were linked to SARS-CoV-2 national test data for the period 01/03/2020 to 31/08/2020. Case definitions were: community-onset community-acquired (CO.CA), first positive test (FPT) <14 days pre-admission, up to day 2 of admission; hospital-onset indeterminate healthcare-associated (HO.iHA), FPT on day 3-7; hospital-onset probable healthcare-associated (HO.pHA), FPT on day 8-14; hospital-onset definite healthcare-associated (HO.HA), FPT from day 15 of admission until discharge; community-onset possible healthcare-associated (CO.pHA), FPT ≤14 days post-discharge. Results: One-third (34.4%, 100,859/293,204) of all laboratory-confirmed COVID-19 cases were linked to a hospital record. HO.pHA and HO.HA cases represented 5.3% (15,564/293,204) of all laboratory-confirmed cases and 15.4% (15,564/100,859) of laboratory-confirmed cases among hospital patients. CO.CA and CO.pHA cases represented 86.5% (253,582/293,204) and 5.1% (14,913/293,204) of all laboratory-confirmed cases, respectively. Conclusions: Up to 1 in 6 SARS-CoV-2 infections among hospitalised patients with COVID-19 in England during the first 6 months of the pandemic could be attributed to nosocomial transmission, but these represent less than 1% of the estimated 3 million COVID-19 cases in this period.

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“…For example, some studies have shown nursing staff to be at increased risk of acquiring both SARS-CoV-2 (16, 24) and SARS-CoV (25), while others have not (26, 27). Duration of patient contact (16) and incorrect use of PPE (28-32) have also been cited as potential contributing factors in SARS-CoV-2 acquisition in health care settings. Whilst occupational risk is often the focus (3, 6, 13, 16), studies continue to highlight the contribution of community acquisition (2, 5, 33, 34).…”

Section: Discussionmentioning

confidence: 99%

SARS-CoV-2 testing of 11,884 healthcare workers at an acute NHS hospital trust in England: a retrospective analysis

Hanrath

Loeff

Lendrem

et al. 2020

Preprint

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Healthcare workers (HCWs) are known to be at increased risk of infection with SARS-CoV-2, although whether these risks are equal across all roles is uncertain. Here we report a retrospective analysis of a large real-world dataset obtained from 10 March to 6 July 2020 in an NHS Foundation Trust in England with 17,126 employees. 3,338 HCWs underwent symptomatic PCR testing (14.4% positive, 2.8% of all staff) and 11,103 HCWs underwent serological testing for SARS-CoV-2 IgG (8.4% positive, 5.5% of all staff). Seropositivity was lower than other hospital settings in England but higher than community estimates. Increased test positivity rates were observed in HCWs from BAME backgrounds and residents in areas of higher social deprivation. A logistic regression model adjusting for these factors showed significant increases in the odds of testing positive in certain occupational groups, most notably domestic services staff, nurses and health-care assistants. PCR testing of symptomatic HCWs appeared to underestimate overall infection levels, probably due to asymptomatic seroconversion. Clinical outcomes were reassuring, with only a small minority of HCWs with COVID-19 requiring hospitalisation (2.3%) or ICU management (0.7%) and with no deaths. Despite a relatively low level of HCW infection compared to other UK cohorts, there were nevertheless important differences in test positivity rates between occupational groups, robust to adjustment for demographic factors such as ethnic background and social deprivation. Quantitative and qualitative studies are needed to better understand the factors contributing to this risk. Robust informatics solutions for HCW exposure data are essential to inform occupational monitoring.

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Investigation of nosocomial SARS-CoV-2 transmission from two patients to healthcare workers identifies close contact but not airborne transmission events

Abstract: ABSTRACT OBJECTIVE To describe the pattern of transmission of SARS-CoV-2 during 2 nosocomial outbreaks of COVID-19 with regard to the possibility of airborne transmission. DESIGN Contact investigations with active case finding were used to assess the pattern of sp… Show more

Cited by 23 publications

References 22 publications

SARS-CoV-2 and Health Care Worker Protection in Low-Risk Settings: a Review of Modes of Transmission and a Novel Airborne Model Involving Inhalable Particles

SARS-CoV-2 and Health Care Worker Protection in Low-Risk Settings: a Review of Modes of Transmission and a Novel Airborne Model Involving Inhalable Particles

Healthcare-associated COVID-19 in England: a national data linkage study

SARS-CoV-2 testing of 11,884 healthcare workers at an acute NHS hospital trust in England: a retrospective analysis

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