Asymptomatic Spread of COVID-19 in 97 Patients at a Skilled Nursing Facility

Background

There are roughly 16,000 nursing homes in the United States caring for more than 1.5 million individuals. This population is at high risk for morbidity and mortality from SARS-CoV-2,¹ with early reports suggesting a COVID-19 case fatality rate of 15% to 20% for those older than 80.^{1 , 2} Unfortunately, outbreaks in nursing homes are being reported with increased frequency and with significant associated mortality.3, 4, 5 The unclear rate of asymptomatic carriers complicates the situation,^{4 , 6} allowing potential transmission among this high-risk population for substantial time before active infection can be identified.

Methods

We analyzed the results of a single universal testing of an asymptomatic population in a single nursing home. Noting the need for specialized care of COVID-19–positive patients in nursing homes following hospital discharge, our team worked to develop a specialized COVID-19 Center of Excellence.⁷ In anticipation of transferring an asymptomatic population out of our proposed site, we mobilized a team of Emergency Medical Services providers trained in administering nasopharyngeal swabs to test all 97 residents for COVID-19. At the time of testing, there were no known or reported cases of active COVID-19 infection among any of the 97 residents or 147 staff members. Samples were transported to the laboratory for real-time SARS-CoV-2 nucleic acid detection (reverse-transcriptase polymerase chain reaction), which is able to detect SARS-CoV-2 with a clinical sensitivity of 70% to 75%. This analysis was deemed exempt from review by our institutional review board.

Results

A total of 97 residents were tested for COVID-19, representing all residents in a single nursing home. The average age was 83, with a minimum of 54 years old and maximum of 102 years old (interquartile range 61–98). Twenty-eight percent of the population was male. Fifty-two patients (53.6%) tested positive for SARS-CoV-2. There were no significant contributions of either age or gender on test result.

Discussion

To our knowledge, this represents the largest universal testing of a suspected asymptomatic population at a single site in the United States. Asymptomatic and presymptomatic spread of SARS-CoV-2 has been previously reported,4, 5, 6 although large-scale testing of asymptomatic populations is not currently common practice. Recent evaluations suggest an alarming rate of asymptomatic and presymptomatic disease prevalence once cases have been identified at a particular site. However, and concerning, in the site evaluated in the current report no suspected cases had been yet reported. Our results suggest SARS-CoV-2 is prevalent in many nursing homes even in the absence of symptomatic individuals.

This nursing home had been closed to visitors and had been practicing physical distancing among residents for 22 days before our evaluation, yet more than 50% of the population tested positive for COVID-19. Several possible explanations exist, including spread from staff members, a known contributor in previous outbreaks,³ and the frequent transfer of patients in and out of the short-term care unit. Further, social distancing among residents proved extremely challenging, particularly on the facility's memory care unit.

Our study has limitations, including the single-site nature of the study and a known and accepted false-positive rate of our test. Further, it is likely that many patients were indeed symptomatic. Many patients suffered from cognitive decline and may have been unable to express symptoms, patients with chronic respiratory conditions may have had symptoms that were not noticed, and mild symptoms may have gone unrecognized. Yet the number of positive cases in this reportedly asymptomatic population is alarming and suggests careful attention must be paid to this population in terms of increased testing, infection control, and advance care planning.

Nursing homes must behave as if all residents and staff are potentially infected once COVID-19 is documented in a community. Until improved options for treatment or vaccines become available, widespread testing among nursing home residents and staff alike should be implemented. Intensive infection control and prevention are essential, and hospitals should implement universal screening of nursing home transfers regardless of symptoms.