McMichael TM, Currie DW et al (2020) Epidmiology of Covid-19 in a Long-Term Care Facility in King County, Washington. N Engl J Med https://www.nejm.org/doi/full/10.1056/NEJMoa2005412

The study:

Following the identification of a resident with COVID-19 in a skilled nursing facility on the 28th February, the Public Health-Seattle and King County (PHSKC), aided by the Centers for Disease Control and Prevention (CDC), carried out an investigation of a cluster of COVID-19-like illness that was occurring at a skilled nursing facility. Data was collected on symptoms, severity, coexisting conditions, travel history and close contacts with known COVID-19 and diagnostic testing was conducted according to CDC guidelines.

At least 100 facilities in the same county were contacted and information was gathered on clusters of influenza-like illness among residents and staff and data was collected on emergency medical transfers to acute care to identify influenza-like illness. All facilities were high risk of COVID-19 were visited and those with influenza-like illnesses were tested. The facilities were given infection control assessments, training and support.

Key Findings:

Testing identified a total of 4 cases of COVID-19 on the 28th February, including the initial resident and a member of staff. On the 18th March there were 167 persons with COVID-19 that were epidemiologically linked to the first facility. Of these, 101 were residents, 50 were staff and 16 were visitors and, by that date, 34 residents and 1 visitor had died.

Another 30 facilities were found to have at least one confirmed COVID-19 case. At least 3 facilities had clear epidemiological links with the first facility where the outbreak was identified. Two of the facilities had staff that also worked in the first facility, and a third facility had received two patient transfers from the first.

The surveys and on-site visits identified the following factors as contributors to the spread of COVID-19 in care facilities:

• Staff who worked while symptomatic
• Staff who worked in more than one facility
• Inadequate familiarity with and adherence to Personal Protection Equipment (PPE) guidance
• Challenges to implementing proper infection control practices, including inadequate supplies of PPE and alcohol-based hand sanitizer
• Delayed recognition of access due to low index of suspicion
• Limited availability of testing
• Difficulty identifying persons with COVID-19 on the basis of signs and symptoms alone

Study limitations report by the authors:

• Some infections will have been missed as not all residents and staff were interviewed and tested for SARS-CoV-2, particularly those who were presymptomatic or asymptomatic
• There were no complete records of visitors to the first facility, so some infections among visitors are likely to have been missed.