Frequency of Routine Testing for Coronavirus Disease 2019 (COVID-19) in High-risk Healthcare Environments to Reduce Outbreaks

Chin, Elizabeth T; Huynh, Benjamin Q.; Chapman, Lloyd A. C.; Basu, Sanjay; Lo, Nathan

doi:10.1093/cid/ciaa1383

Cited by 91 publications

(95 citation statements)

References 11 publications

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“…Testing 2-3 times per week is suggested for optimal public health impact. 20 In the UK, screening showed lower sensitivity when tests were performed by testers who were not health care workers than when they were performed by health care workers; however, the discrepancy disappeared over a 2-week period, which suggests that workers who are not trained in health care can be taught with experience to adequately perform swabs. 16 Preprint research has shown that self-testing may have similar performance to swabs taken by professionals, 21 and home-based use needs urgent evaluation to facilitate scalability and minimize biosafety concerns.…”

Section: How Can Rapid Antigen Testing Be Incorporated Into Canada'smentioning

confidence: 98%

Rapid antigen screening of asymptomatic people as a public health tool to combat COVID-19

Schwartz

McGeer

Bogoch

2021

CMAJ

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J urisdictions across Canada have been trying to combat a second wave of the coronavirus disease 2019 (COVID-19) pandemic without using all the available tools. Accumulating evidence has shown that people who are infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who are either presymptomatic (but subsequently develop symptoms) or paucisymptomatic (have mild symptoms that do not prompt a medical visit) are major contributors to transmission. However, current approaches of testing predominately symptomatic patients and relying on the results of expensive and slow laboratory-based testing for contact tracing have proven inadequate to control the spread of the disease, with associated economic and societal impacts. Frequent rapid antigen testing is a scalable public health tool that can efectively identify asymptomatic and paucisymptomatic people with SARS-CoV-2 infection and improve contact tracing and control of outbreaks. Why test people who have no symptoms of COVID-19? A 2020 study of transmission dynamics in Taiwan showed that the infectious period for COVID-19 starts 2-3 days before symptom onset and continues to about 5 days afer. 1 Modelling has estimated that more than 50% of SARS-CoV-2 transmissions occur during the presymptomatic period or during asymptomatic infection. 2,3 A study in which the authors reconstructed transmission in China up to April 2020 found that presymptomatic transmission accounted for a high proportion (40%-90%) of transmissions. 4 Furthermore, higher viral loads have been shown to be significantly associated with higher transmission risk irrespective of symptoms. 5 Even with ideal public health resources for testing and tracing, the strategy of testing only symptomatic cases will not identify many of the contacts before they transmit infection. A report from the Ofice of the Auditor General of Ontario indicated that the average time from specimen collection to the start of case and contact management was 4.25 days. 6 In this scenario, for patients who seek testing on their first day of symptoms, on KEY POINTS • People who are presymptomatic and paucisymptomatic are important contributors to the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). What rapid antigen tests are available and how should they be evaluated? Although many diferent devices are being produced, the Abbott Panbio lateral flow assay is the only device with Health Canada approval at the time of writing. Lateral flow assays detect a protein

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Section: How Can Rapid Antigen Testing Be Incorporated Into Canada'smentioning

confidence: 98%

Rapid antigen screening of asymptomatic people as a public health tool to combat COVID-19

Schwartz

McGeer

Bogoch

2021

CMAJ

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“…Models of similar settings have also found the frequency of testing required to control outbreaks can be dependent on community prevalence. 19 The timing of this transition, and how it should be implemented, may be an important area for future work.…”

Section: (Which Was Not Certified By Peer Review)mentioning

confidence: 99%

Frequent testing and immunity-based staffing will help mitigate outbreaks in nursing home settings

Holmdahl

Kahn

Hay

et al. 2020

Preprint

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Background: Nursing homes and other long term care facilities have been disproportionately impacted by the COVID-19 pandemic. Strategies are urgently needed to reduce transmission in these vulnerable populations. We aimed to evaluate the reduction in transmission in nursing homes achieved through contact-targeted interventions and testing and to evaluate the effectiveness of two types of screening tests conducted with varying frequency: 1) rapid antigen testing and 2) PCR testing. Methods: We developed an agent-based Susceptible-Exposed-Infectious(Asymptomatic/Symptomatic)-Recovered (SEIR) model to examine SARS-CoV-2 transmission in nursing homes. Residents and staff are modelled individually; residents are split into two cohorts based on COVID-19 diagnosis. In the resident cohorting intervention, recovered residents are moved back from the COVID (infected) cohort to the non-COVID (susceptible/uninfected) cohort. In the immunity-based staffing intervention, recovered staff, who we assume have protective immunity, are assigned to work in the non-COVID cohort, while susceptible staff work in the COVID cohort and are assumed to have high levels of protection from personal protective equipment. These interventions aim to reduce the fraction of people's contacts that are presumed susceptible (and therefore potentially infected) and replace them with recovered (immune) contacts. Results: The frequency and type of testing has a larger impact on the size of outbreaks than the cohorting and staffing interventions. The most effective testing strategies modeled are daily antigen testing of everyone and daily antigen testing of staff with weekly PCR testing for residents. Under all screening testing strategies, the immunity-based staffing intervention reduces the final size of the outbreak. The resident cohorting intervention reduces the final outbreak size under some, but not all, testing scenarios. Conclusions: Increasing the frequency of screening testing of all residents and staff, or even staff alone, in nursing homes has the potential to greatly reduce outbreaks in this vulnerable setting. Immunity-based staffing can further reduce spread at little or no additional cost and becomes particularly important when daily testing is not feasible.

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“…Several modeling studies now support mass testing in healthcare settings to prevent asymptomatic spread. 5 , 6 Our experience suggests there could be substantial benefit in encouraging testing of staff with any degree of symptoms, even mild because up to half of positive HCP would be detected by this strategy.…”

Section: Discussionmentioning

confidence: 98%

Mass severe acute respiratory coronavirus 2 (SARS-CoV-2) testing of asymptomatic healthcare personnel

Peaper

Thorne

Sussman

et al. 2021

Infect. Control Hosp. Epidemiol.

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Frequency of Routine Testing for Coronavirus Disease 2019 (COVID-19) in High-risk Healthcare Environments to Reduce Outbreaks

Cited by 91 publications

References 11 publications

Rapid antigen screening of asymptomatic people as a public health tool to combat COVID-19

Rapid antigen screening of asymptomatic people as a public health tool to combat COVID-19

Frequent testing and immunity-based staffing will help mitigate outbreaks in nursing home settings

Mass severe acute respiratory coronavirus 2 (SARS-CoV-2) testing of asymptomatic healthcare personnel

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