The vulnerability of long-term care facilities to respiratory disease outbreaks, including influenza and other commonly circulating human coronaviruses such as the common cold, is well recognized.16,17 As this report shows, the spread of Covid-19 reflected the same vulnerability in at least one long-term care facility. In total, 167 confirmed cases of Covid-19 had been identified among residents, personnel, and visitors as of March 18, and 30 skilled nursing and assisted living facilities in King County had identified at least one confirmed case of Covid-19. Staff working in multiple facilities while ill and transfers of patients from one facility to another potentially introduced Covid-19 into some of these facilities. The transmission within Facility A and to other facilities in the area posed a serious threat to the medically vulnerable population residing within long-term care facilities and strained the local acute care hospitals. Although the use of vaccine and antiviral medications can be effective in reducing the spread of influenza in long-term care facilities, such interventions are not currently available for Covid-19.18 Residents and health care personnel at long-term care facilities are at risk for Covid-19 transmission and severe outcomes, particularly for residents who are predominantly at advanced ages and have underlying medical conditions. Publicly available information on staffing and quality measures shows no indication that baseline practices at Facility A placed residents at greater risk than residents at other similar facilities.

This investigation had a number of limitations. Not all residents and staff were interviewed and tested for SARS-CoV-2, which might have led to under-ascertainment of infections, particularly for those who were presymptomatic or asymptomatic. For example, at another facility (Facility B) that had a subsequent Covid-19 outbreak epidemiologically linked to Facility A, swabbing of all residents revealed that infections with low cycle threshold values (indicating a large quantity of viral RNA) occurred among some residents who did not have symptoms.19 There was not a complete roster of visitors to Facility A, and it is possible that some infections among visitors were also missed by these surveillance and investigation efforts. Because symptom onset dates were not available in many cases, the epidemic curve is presented by date of report; however, this does not adequately represent the timing of disease onset in the facility, given that the median time from symptom onset to diagnosis in this cohort was 8 days but had considerable variability. Finally, case ascertainment and testing ramped up after the outbreak was recognized at Facility A, but there could have been infections and transmission at other facilities in the area earlier.

On March 10, 2020, the governor of Washington implemented mandatory screening of health care workers and visitor restrictions for all licensed nursing homes and assisted living facilities.20 These strategies are coordinated and supported by public health authorities, partnering health care systems, regulatory agencies, and their respective governing bodies.20-23 Local and state authorities strengthened prevention and mitigation strategies targeting transmission of Covid-19 and other respiratory viruses in long-term care facilities that include screening and restricted access policies for visitors and nonessential personnel; screening of health care personnel, including measurement of body temperature and interviewing for presence of respiratory symptoms, to identify and exclude symptomatic workers; strategies for close clinical monitoring of residents; social distancing, including restricting resident movement and group activities; staff training on infection prevention and control and PPE use; and establishment of plans for county and state coordination of needs and contingency plans for acquiring PPE in anticipation of delays or interruptions in supply.20,22,24,25 In addition to education, hands-on training, and maintaining adequate supplies, facilities need to reinforce staff adherence to infection prevention and control practices with regular auditing and feedback from observation of staff workflow. Substantial disruptions, such as staff absenteeism and increased workload, may affect the consistency with which these practices are implemented and monitored. The impact of these policies in protecting long-term care facilities should continue to be evaluated, along with the role of serial testing strategies to identify infected staff or patients as testing reagents and supplies become more available.

The experience described here indicates that outbreaks of Covid-19 in long-term care facilities can have a considerable impact on vulnerable older adults and local health care systems. The findings also suggest that once Covid-19 has been introduced into a long-term care facility, it has the potential to spread rapidly and widely. This can cause serious adverse outcomes among facility residents and staff, which underscores the importance of proactive steps to identify and exclude potentially infected staff and visitors, early recognition of potentially infected patients, and implementation of appropriate infection prevention and control measures.21-24,26 Lessons learned from this initial cluster can provide valuable guidance for long-term care facilities in other parts of the United States.