key: cord-0944109-pvxbpbso
authors: Walsh, Jennifer; Skally, Mairead; Duffy, Fionnuala; Kalukondanahally, Giri; Dinesh, Binu; O’Connell, Karina; de Barra, Eoghan; Burns, Karen; Fitzpatrick, Fidelma
title: The early test catches the case. Why wait? Frequent testing of close contacts aids COVID-19 control
date: 2021-08-14
journal: J Hosp Infect
DOI: 10.1016/j.jhin.2021.08.004
sha: 7ac61c37f58b0175c468a3ea5dc8bd31c2c6338c
doc_id: 944109
cord_uid: pvxbpbso

nan

One of the significant challenges in hospitals during the coronavirus disease 2019 pandemic has been prevention of nosocomial transmission. As the pandemic evolved, the hospital infection prevention and control (IPC) approach has differed considerably from previously, including the implementation of universal SARS-CoV-2 admission testing and asymptomatic patient and staff testing as part of ward outbreak management [1, 2] . As shared patient accommodation along with staff movement enhances SARS-CoV-2 transmission, timely identification and management of positive patients and close contacts has been key [3] .

Of 820 beds in our institution, only 136 are single rooms, 77% with en suite facilities and 12 airborne isolation rooms. Most accommodation is multi-occupancy; comprising six-, four-or two-bedded rooms, with one shared bathroom. All patients in a shared bay are considered COVID-19 close contacts when a positive 'index' patient is detected in that bay, day zero being the date of index patient positivity. Close contacts are either isolated or cohorted for 14 days, or advised to restrict movements if discharged within 14 days. Up to November 2020, close contact patients were tested on day zero and day seven after index patient detection. Aside from close contact testing, indications for repeat SARS-CoV-2 testing included surgery, discharge to another healthcare facility and development of symptoms.

Because of the five-day median incubation period, we were concerned that undetected potentially infectious close contacts remained in multi-bedded bays until tested on day seven J o u r n a l P r e -p r o o f 3 [4] . Likewise, undetected patients who became positive thereafter could pose an IPC risk.

Effective 18 th November 2020, we commenced testing inpatient close contacts every 48 hours up to day 14 and describe our experience to 14 th February 2021. Inpatients deemed a COVID-19 close contact in the community were excluded, as 'day zero' could not be reliably ascertained. For each close contact, day zero was the date of exposure to the index patient. Previous studies have demonstrated the correlation between hospital ward design and nosocomial infection rates [5] . Limited isolation facilities are a reality across Europe, with the median proportion of hospital single rooms at 24.2% [6] . Patients with nosocomial COVID-19 tend to be older and frailer with higher mortality, highlighting the need to maximize IPC efforts J o u r n a l P r e -p r o o f 4 to prevent cross-transmission [7] . Frequent testing of hospitalized close contact patients is especially important in our institution, because of our infrastructure. While we have no patient symptom data, IPC action is required irrespective, because of infectivity during the incubation period [4] . To date, there is surprisingly little in the literature regarding optimal testing schedules for inpatient close contacts. With the dominance of the delta variant with higher infectivity and shorter median incubation periods (four days), rapid detection and isolation of asymptomatic COVID-19 patients will become particularly important as winter approaches [8] . 

Casting the net wide: universal testing of emergency admissions for SARS-CoV-2 to prevent onward transmission

The role of healthcare staff COVID-19 screening in infection prevention & control

Nosocomial Transmission of Coronavirus Disease 2019: A Retrospective Study of 66 Hospitalacquired Cases in a London Teaching Hospital

The Incubation Period of Coronavirus Disease 2019 (COVID-19) from Publicly Reported Confirmed Cases: Estimation and Application

Relationship between hospital ward design and healthcare-associated infection rates: a systematic review and metaanalysis

European Centre for Disease Prevention and Control. Point prevalence survey of healthcare associated infections and antimicrobial use in European acute care hospitals

Burden of nosocomial COVID-19 in Wales: results from a multicentre retrospective observational study of 2508 hospitalised adults

Viral infection and transmission in a large welltraced outbreak caused by the Delta SARS-CoV-2 variant