key: cord-0914507-h4gy1eya
authors: Long, Dustin R; O’Reilly-Shah, Vikas; Rustagi, Alison S; Bryson-Cahn, Chloe; Jerome, Keith R; Weiss, Noel S; Sunshine, Jacob E
title: Incidence of Healthcare-Associated COVID-19 During Universal Testing of Medical and Surgical Admissions in a Large US Health System
date: 2020-09-14
journal: Open Forum Infect Dis
DOI: 10.1093/ofid/ofaa435
sha: 77c0e6f65eda376aca6453e4056387edfabf5c83
doc_id: 914507
cord_uid: h4gy1eya

Concerns about SARS-CoV-2 exposure in healthcare settings may cause patients to delay care. Among 2992 patients testing negative on admission to an academic, three-hospital system, 8 tested positive during hospitalization or within 14 days post-discharge. Following adjudication of each instance, healthcare-associated infection incidence ranged from 0.8-5.0 cases per 10,000 patient-days.

SARS-CoV-2 is the etiologic agent of COVID-19, which in 2020 has caused over 180,000 deaths in the United States. 1 Concerns related to the risk of SARS-CoV-2 exposure within healthcare environments have caused patients to avoid seeking care. In Italy, for example, rates of hospital admission for acute coronary syndrome were one-quarter lower during the COVID-19 outbreak compared to rates earlier in 2020 or in the same period during 2019 2 ; in the United States, at the beginning of the pandemic, emergency room visits declined 42% compared to the same period in the year prior. 3 As the US moves into the next phase of the pandemic, patients may continue to exercise discretion with respect to seeking needed and elective medical care, due to concerns about transmission of the virus within healthcare settings. Such decisions have considerable implications for outpatient and inpatient medical and surgical care 4, 5 and for the financial viability of health systems continuing to provide health care services. Thus, we sought to better understand the risk of healthcare-associated SARS-CoV-2 acquisition in the context of current infection control practices. The University of Washington (UW) medical system initiated universal testing of all admitted surgical patients on March 30 th , 2020, and all admitted medical patients on April 13 th , 2020 and serves as a regional referral laboratory for SARS-CoV-2 tests. These factors enable measurement of incident healthcare-associated SARS-CoV-2 acquisition among a cohort of patients known to be test-negative at the time of admission to a healthcare environment.

UW Medicine is a three-hospital academic health system located in Seattle, Washington.

Results of all SARS-CoV-2 tests performed on admission to UW Medicine hospitals from April 2nd, 2020 through May 14th, 2020 were analyzed. During this period, universal testing of patients entering these hospitals was required: a) within 72 hours prior to planned surgical procedures and b) beginning April 13th, at the time of all other inpatient admissions. All screening tests were collected using nasopharyngeal swabs and analyzed by reverse Repeat test results were evaluated through an observation period extending 14 days beyond discharge to account for healthcare-associated infections which may have occurred just prior to discharge. (Patients who may have been admitted subsequently to their initial admission, but after the post-discharge 14-day monitoring period, only contributed exposure time during the initial admission). Test results were extracted for analysis on May 28th to allow a full 14day observation period for all included patients.

Potential healthcare-associated COVID-19 infections detected using this approach were cross-checked with an institutional database of clinical reviews maintained by the UW Infection Prevention and Control program. The frequency of short-term (within 7 days) SARS-CoV-2 NP test discordance among initially test-negative patients in the UW system during a similar period has been estimated at 4.1% and was similar to one other large academic medical system. 7 All patients with potential newly positive tests were subject to structured chart review. Final determinations (healthcare-associated vs. non-healthcare- 

Initial screening test results from 3053 patients entering the health system during the study period were reviewed. Those with a documented prior positive result (n=33) were excluded. Among the 2992 asymptomatic individuals with negative screening tests at the time of entrance into the health system, average length of inpatient stay was 6.1 days (interquartile range 6), representing a range of 11,971 to 11,981 patient-days at risk within an inpatient environment, dependent on results of consensus classification of healthcare-associated infection status. Of these 2,992 patients, 28.1% were retested one or more times during the observation period (12.4% during hospitalization, 11.9% within 14 days of discharge, and 3.9% both). Repeat testing in this initially negative group was most often performed for A c c e p t e d M a n u s c r i p t 6 ongoing procedural or discharge surveillance (90%), but occasionally due to new onset of symptoms concerning for COVID-19 (10%).

During the study period, 8 cases of possible incident SARS-CoV-2 positivity were observed among patients testing negative at the time of admission. After consensus review, 2 patients were classified as 'Definitely not HAI'; 3 patients were classified as 'Likely not HAI'; 2 patients were classified as 'Possibly HAI'; 1 patient was classified as 'Likely HAI'; and 0 patients were classified as 'Definitely HAI'. Accounting for these cases, during the study period, there was a range from 1 to 6 potential cases among this study population, indicating a range of 0.8 to 5.0 cases per 10,000 patient-days. Of note, none of these cases were related and no outbreak/cluster of COVID-19 was suspected among patients within UW Medicine hospitals during the period under investigation.

In this work, it was observed that the incidence of hospital-acquired SARS-CoV-2 infection within a single, large health system during a period of universal admission testing was relatively low. Other reports have found annualized hospital-associated respiratory viral infection rates to be approximately 4.9 (95%, 4.7-5.2) cases per 10,000 patient-days, 9 consistent with the upper range of our estimate for SARS-CoV-2. As health systems and public health authorities communicate the need to avoid foregoing necessary clinical care, transparent enumeration of the risks of SARS-CoV-2 transmission within healthcare settings will be essential. Such communication is important as patients delay or avoid seeking care for several time-sensitive indications, including childhood vaccination 3 , acute coronary syndrome 2 and stroke. 4 There are limitations to this study. These results represent the experience of 3 hospitals of one major academic medical system; as infection control practices vary widely, these results may not be generalizable to other health systems. Approximately 1 in 4 patients were A c c e p t e d M a n u s c r i p t 7 retested following their negative admission RT-PCR result; among retested patients not undergoing mandated surveillance for administrative indications (i.e., prior to facility transfer or before a procedure), the chance of subsequent testing may have favored patients with concern for SARS-CoV-2, which could bias these results toward a higher healthcare- Table 1 ) and utilized contextual data on institutional rates of short-term nasopharyngeal test discordance 7 (i.e. testing negative initially then testing positive shortly thereafter) to interpret such cases. Finally, the period under investigation occurred after the cases in King County, Washington surpassed their peak and the overall census of UW Medicine inpatients with COVID-19 had begun to decline. It is possible that the risk of healthcare-associated COVID-19 infection was higher during this earlier period when overall disease prevalence was increasing and prior to the standardization of current infection control procedures.

A c c e p t e d M a n u s c r i p t 8 Ongoing evaluation of hospital-acquired transmission rates is critical to ensuring patient and staff safety, earning patient trust, and identifying and addressing any risk factors for transmission as they emerge. As health systems and patients adapt to the ongoing US COVID-19 crisis, patients will continue to seek information regarding the risks of presenting for necessary medical and surgical care in this new environment. These data indicate that, in health systems with comparable infection control practices, the risk of healthcare associated SARS-CoV-2 transmission may be relatively low. A c c e p t e d M a n u s c r i p t

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