CDC: Coronavirus Screening Fails to Identify Half of Cases Among Nursing Home Residents

New research from the federal government indicates that residents without COVID-19 symptoms can play a key role in the spread of the virus in nursing homes, with more than half of positive tests at a facility in Washington state coming from patients with no outward signs of infection.

Of the 23 positive tests logged at a nursing home in King County, Wash., 57% were associated with residents who did not display any symptoms of COVID-19 infection beforehand, according to early findings released by the Centers for Disease Control and Prevention (CDC).

Within seven days of the test, 10 of the 13 residents who had tested positive while displaying no symptoms began to show signs of the disease, the researchers found.


“Symptom-based screening in SNFs could fail to identify approximately half of residents with COVID-19,” the CDC team, which included a variety of public health officials in Washington state, concluded. “Long-term care facilities should take proactive steps to prevent introduction of SARS-CoV-2. Once a confirmed case is identified in an SNF, all residents should be placed on isolation precautions if possible, with considerations for extended use or reuse of personal protective equipment (PPE) as needed.”

Since the start of the outbreak, skilled nursing operators across the country have used screening of residents, health care workers, and other potential visitors to help prevent the spread of the virus. Even in the wake of a blanket ban on all non-essential nursing home visitors, the Centers for Medicare & Medicaid Services (CMS) advised that anyone displaying symptoms of COVID-19 infection should not be allowed inside.

“Those with symptoms of a respiratory infection (fever, cough, shortness of breath, or sore throat) should not be permitted to enter the facility at any time (even in end-of-life situations),” CMS advised.


But the CDC’s findings indicate that such strategies may not be enough to prevent the spread.

“If asymptomatic or pre-symptomatic residents play an important role in transmission in this population at high risk, additional prevention measures merit consideration, including using testing to guide cohorting strategies or using transmission-based precautions for all residents of a facility after introduction of SARS-CoV-2,” the CDC observed.

Further complicating the issue is a lack of widely available testing for the virus — along with the fact that viral infections among the elderly can cause atypical symptoms, according to the CDC. Residents in the nursing home setting are also not always able to describe their symptoms, the researchers noted.

“Symptom ascertainment and room isolation can be exceptionally challenging in elderly residents with neurologic conditions, including dementia,” the CDC noted. “In addition, symptoms of COVID-19 are common and might have multiple etiologies in this population; 24.5% of facility A residents with negative test results for SARS-CoV-2 reported typical or atypical symptoms.”

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