Epidemiology of Covid-19 in a Long-Term Care Facility in King County, Washington.

BACKGROUND: Long-term care facilities are high-risk settings for severe outcomes from outbreaks of Covid-19, owing to both the advanced age and frequent chronic underlying health conditions of the residents and the movement of health care personnel among facilities in a region. METHODS: After identification on February 28, 2020, of a confirmed case of Covid-19 in a skilled nursing facility in King County, Washington, Public Health-Seattle and King County, aided by the Centers for Disease Control and Prevention, launched a case investigation, contact tracing, quarantine of exposed persons, isolation of confirmed and suspected cases, and on-site enhancement of infection prevention and control. RESULTS: As of March 18, a total of 167 confirmed cases of Covid-19 affecting 101 residents, 50 health care personnel, and 16 visitors were found to be epidemiologically linked to the facility. Most cases among residents included respiratory illness consistent with Covid-19; however, in 7 residents no symptoms were documented. Hospitalization rates for facility residents, visitors, and staff were 54.5%, 50.0%, and 6.0%, respectively. The case fatality rate for residents was 33.7% (34 of 101). As of March 18, a total of 30 long-term care facilities with at least one confirmed case of Covid-19 had been identified in King County. CONCLUSIONS: In the context of rapidly escalating Covid-19 outbreaks, proactive steps by long-term care facilities to identify and exclude potentially infected staff and visitors, actively monitor for potentially infected patients, and implement appropriate infection prevention and control measures are needed to prevent the introduction of Covid-19.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Transmission Associated With an Indoor Music Event That Required Proof of Full Vaccination Against Coronavirus Disease 2019 (COVID-19) Prior to Entry-Seattle, July 2021.

In July 2021, Public Health-Seattle & King County investigated a coronavirus disease 2019 (COVID-19) outbreak at an indoor event intended for fully vaccinated individuals, revealing unvaccinated staff, limited masking, poor ventilation, and overcrowding. Supporting businesses to develop and implement comprehensive COVID-19 prevention plans is essential for reducing spread in these settings.

Household Transmission of SARS-CoV-2 from Humans to Pets, Washington and Idaho, USA.

SARS-CoV-2 likely emerged from an animal reservoir. However, the frequency of and risk factors for interspecies transmission remain unclear. We conducted a community-based study in Idaho, USA, of pets in households that had >1 confirmed SARS-CoV-2 infections in humans. Among 119 dogs and 57 cats, clinical signs consistent with SARS-CoV-2 were reported for 20 dogs (21%) and 19 cats (39%). Of 81 dogs and 32 cats sampled, 40% of dogs and 43% of cats were seropositive, and 5% of dogs and 8% of cats were PCR positive. This discordance might be caused by delays in sampling. Respondents commonly reported close human‒animal contact and willingness to take measures to prevent transmission to their pets. Reported preventive measures showed a slightly protective but nonsignificant trend for both illness and seropositivity in pets. Sharing of beds and bowls had slight harmful effects, reaching statistical significance for sharing bowls and seropositivity.

COVID-19 Surveillance and Investigations in Workplaces - Seattle & King County, Washington, June 15-November 15, 2020.

Workplace activities involving close contact with coworkers and customers can lead to transmission of SARS-CoV-2, the virus that causes COVID-19 (1,2). Information on the approach to and effectiveness of COVID-19 workplace investigations is limited. In May 2020, Public Health - Seattle & King County (PHSKC), King County, Washington established a COVID-19 workplace surveillance and response system to enhance COVID-19 contact tracing and identify outbreaks in workplaces. During June 15-November 15, 2020, a total of 2,881 workplaces in King County reported at least one case of COVID-19. Among 1,305 (45.3%) investigated workplaces,* 524 (40.3%) met the definition of a workplace outbreak.† Among 306 (58.4%) workplaces with complete data,§ an average of 4.4 employee COVID-19 cases¶ (median = three; range = 1-65) were identified per outbreak, with an average attack rate among employees of 17.5%. PHSKC and the Washington State Department of Health optimized resources by establishing a classification scheme to prioritize workplace investigations as high, medium, or low priority based on workplace features observed to be associated with increased COVID-19 spread and workforce features associated with severe disease outcomes. High-priority investigations were significantly more likely than medium- and low-priority investigations to have two or more cases among employees (p<0.001), two or more cases not previously linked to the workplace (p<0.001), or two or more exposed workplace contacts not previously identified during case interviews (p = 0.002). Prioritization of workplace investigations allowed for the allocation of limited resources to effectively conduct workplace investigations to limit the potential workplace spread of COVID-19. Workplace investigations can also serve as an opportunity to provide guidance on preventing workplace exposures to SARS-CoV-2, facilitate access to vaccines, and strengthen collaborations between public health and businesses.

Investigation and Serologic Follow-Up of Contacts of an Early Confirmed Case-Patient with COVID-19, Washington, USA.

We describe the contact investigation for an early confirmed case of coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in the United States. Contacts of the case-patient were identified, actively monitored for symptoms, interviewed for a detailed exposure history, and tested for SARS-CoV-2 infection by real-time reverse transcription PCR (rRT-PCR) and ELISA. Fifty contacts were identified and 38 (76%) were interviewed, of whom 11 (29%) reported unprotected face-to-face interaction with the case-patient. Thirty-seven (74%) had respiratory specimens tested by rRT-PCR, and all tested negative. Twenty-three (46%) had ELISA performed on serum samples collected ≈6 weeks after exposure, and none had detectable antibodies to SARS-CoV-2. Among contacts who were tested, no secondary transmission was identified in this investigation, despite unprotected close interactions with the infectious case-patient.

COVID-19 in a Long-Term Care Facility - King County, Washington, February 27-March 9, 2020.

On February 28, 2020, a case of coronavirus disease (COVID-19) was identified in a woman resident of a long-term care skilled nursing facility (facility A) in King County, Washington.* Epidemiologic investigation of facility A identified 129 cases of COVID-19 associated with facility A, including 81 of the residents, 34 staff members, and 14 visitors; 23 persons died. Limitations in effective infection control and prevention and staff members working in multiple facilities contributed to intra- and interfacility spread. COVID-19 can spread rapidly in long-term residential care facilities, and persons with chronic underlying medical conditions are at greater risk for COVID-19-associated severe disease and death. Long-term care facilities should take proactive steps to protect the health of residents and preserve the health care workforce by identifying and excluding potentially infected staff members and visitors, ensuring early recognition of potentially infected patients, and implementing appropriate infection control measures.

Notes from the Field: Fatal Infection Associated with Equine Exposure - King County, Washington, 2016.

On March 17, 2016, Public Health-Seattle & King County in Washington was notified of two persons who received a diagnosis of Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) infections. S. zooepidemicus is a zoonotic pathogen that rarely causes human illness and is usually associated with consuming unpasteurized dairy products or with direct horse contact (1). In horses, S. zooepidemicus is a commensal bacterium that can cause respiratory, wound, and uterine infections (2). The health department investigated to determine the magnitude of the outbreak, identify risk factors, and offer recommendations.

Notes from the Field: Outbreak of Multidrug-Resistant Salmonella Infections Linked to Pork--Washington, 2015.

During June-July 2015, Public Health-Seattle & King County (PHSKC) and Washington State Department of Health (WADOH) investigated 22 clusters of Salmonella serotype I 4,[5], 12:i:- infections. Serotype I 4,[5], 12:i:- is the fifth most frequently reported Salmonella serotype in the United States, but is uncommon in Washington. On July 29, 2015, WADOH and PHSKC requested assistance from CDC to identify the infection source, determine risk factors, and make recommendations for prevention.

Household transmission of SARS-CoV-2 from humans to pets in Washington and Idaho: burden and risk factors.

SARS-CoV-2 is believed to have emerged from an animal reservoir; however, the frequency of and risk factors for inter-species transmission remain unclear. We carried out a community-based study of pets in households with one or more confirmed SARS-CoV-2 infection in humans. Among 119 dogs and 57 cats with completed surveys, clinical signs consistent with SARS-CoV-2 were reported in 20 dogs (21%) and 19 cats (39%). Out of 81 dogs and 32 cats sampled for testing, 40% of dogs and 43% of cats were seropositive, and 5% of dogs and 8% of cats were PCR positive; this discordance may be due to delays in sampling. Respondents commonly reported close human-animal contact and willingness to take measures to prevent transmission to their pets. Reported preventative measures showed a slightly protective trend for both illness and seropositivity in pets, while sharing of beds and bowls had slight harmful effects.

Genomic epidemiology of nontoxigenic Corynebacterium diphtheriae from King County, Washington State, USA between July 2018 and May 2019.

Between July 2018 and May 2019, Corynebacterium diphtheriae was isolated from eight patients with non-respiratory infections, seven of whom experienced homelessness and had stayed at shelters in King County, WA, USA. All isolates were microbiologically identified as nontoxigenic C. diphtheriae biovar mitis. Whole-genome sequencing confirmed that all case isolates were genetically related, associated with sequence type 445 and differing by fewer than 24 single-nucleotide polymorphisms (SNPs). Compared to publicly available C. diphtheriae genomic data, these WA isolates formed a discrete cluster with SNP variation consistent with previously reported outbreaks. Virulence-related gene content variation within the highly related WA cluster isolates was also observed. These results indicated that genome characterization can readily support epidemiology of nontoxigenic C. diphtheriae.

Multidrug-Resistant Salmonella I 4,[5],12:i:- and Salmonella Infantis Infections Linked to Whole Roasted Pigs from a Single Slaughter and Processing Facility.

We describe two outbreaks of multidrug-resistant (MDR) Salmonella I 4,[5],12:i:- infection, occurring in 2015 to 2016, linked to pork products, including whole roaster pigs sold raw from a single Washington slaughter and processing facility (establishment A). Food histories from 80 ill persons were compared with food histories reported in the FoodNet 2006 to 2007 survey of healthy persons from all 10 U.S. FoodNet sites who reported these exposures in the week before interview. Antimicrobial susceptibility testing and whole genome sequencing were conducted on selected clinical, food, and environmental isolates. During 2015, a total of 192 ill persons were identified from five states; among ill persons with available information, 30 (17%) of 180 were hospitalized, and none died. More ill persons than healthy survey respondents consumed pork (74 versus 43%, P < 0.001). Seventeen (23%) of 73 ill persons for which a response was available reported attending an event where whole roaster pig was served in the 7 days before illness onset. All 25 clinical isolates tested from the 2015 outbreak and a subsequent 2016 smaller outbreak (n = 15) linked to establishment A demonstrated MDR. Whole genome sequencing of clinical, environmental, and food isolates (n = 69) collected in both investigations revealed one clade of highly related isolates, supporting epidemiologic and traceback data that establishment A as the source of both outbreaks. These investigations highlight that whole roaster pigs, an uncommon food vehicle for MDR Salmonella I 4,[5],12:i:- outbreaks, will need further attention from food safety researchers and educators for developing science-based consumer guidelines, specifically with a focus on the preparation process.