BACKGROUND: Short-term rehabilitation units present unique infection control challenges due to high turnover and medically complex residents. In June 2021, Maricopa County Department of Public Health (MCDPH) was notified of a SARS-CoV-2 Delta outbreak in a skilled nursing facility short-term rehabilitation unit. We describe the outbreak and assess vaccine effectiveness (VE). METHODS: Facility electronic medical records were reviewed for residents who spent >1 night on the affected unit between June 10-July 23, 2021, to collect demographics, SARS-CoV-2 test results, underlying medical conditions, vaccination status, and clinical outcomes. COVID-19 VE estimates using Cox proportional hazards models were calculated. RESULTS: Forty (37%) of 109 short-stay rehabilitation unit residents who met inclusion criteria tested positive for SARS-CoV-2. SARS-CoV-2 positive case-patients were mostly male (58%) and white (78%) with a median age of 65 (range: 27-92) years; 11 (27%) were immunocompromised. Of residents, 39% (10 cases; 32 non-cases) received 2-doses and 9% (4 cases, 6 non-cases) received 1-dose of mRNA vaccine. Among non-immunocompromised residents, adjusted 2-dose primary-series mRNA VE against symptomatic infection was 80% (95% CI: 15, 95). More cases were hospitalized (33%) or died (38%) than non-cases (10% hospitalized; 16% died). CONCLUSIONS: In this large SARS-CoV-2 Delta outbreak in a high-turnover short term rehabilitation unit, a low vaccination rate and medically complex resident population were noted alongside severe outcomes. VE of 2-dose primary-series mRNA vaccine against symptomatic infection was the highest in non-immunocompromised residents. Health departments can use vaccine coverage data to prioritize facilities for assistance in preventing outbreaks.

We quantify antibody and memory B-cell responses to severe acute respiratory syndrome coronavirus 2 at 6 and 12 months postinfection among 7 unvaccinated US coronavirus disease 2019 cases. All had detectable S-specific memory B cells and immunoglobulin G at both time points, with geometric mean titers of 117.2 BAU/mL and 84.0 BAU/mL at 6 and 12 months, respectively.

The Maricopa County Department of Public Health in Arizona investigated three COVID-19 outbreaks associated with club sports, two in tournaments and one in a hockey league. During September through November 2020, 195 team-associated and 69 secondary household contact cases were identified among 2093 athletes, coaches, and staff members; the team attack rate ranged from 6% to 72%. Outbreaks occurred during high community transmission periods in Maricopa County. Identification of contacts and characterization of prevention strategies were challenging because of limited cooperation from athletes, families, and staff. (Am J Public Health. 2022;112(2):216-219. https://doi.org/10.2105/AJPH.2021.306579).

CDC recommends universal indoor masking by students, staff members, faculty, and visitors in kindergarten through grade 12 (K-12) schools, regardless of vaccination status, to reduce transmission of SARS-CoV-2, the virus that causes COVID-19 (1). Schools in Maricopa and Pima Counties, which account for >75% of Arizona's population (2), resumed in-person learning for the 2021-22 academic year during late July through early August 2021. In mid-July, county-wide 7-day case rates were 161 and 105 per 100,000 persons in Maricopa and Pima Counties, respectively, and 47.6% of Maricopa County residents and 59.2% of Pima County residents had received at least 1 dose of a COVID-19 vaccine. School districts in both counties implemented variable mask policies at the start of the 2021-22 academic year (Table). The association between school mask policies and school-associated COVID-19 outbreaks in K-12 public noncharter schools open for in-person learning in Maricopa and Pima Counties during July 15-August 31, 2021, was evaluated.

BACKGROUND: Coronavirus disease 2019 (COVID-19) causes a range of illness severity. Mild illness has been reported, but whether illness severity correlates with infectivity is unknown. We describe the public health investigation of a mildly ill, non-hospitalized COVID-19 case who traveled to China. METHODS: The case was a Maricopa County resident with multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive specimens collected on January 22, 2020. Contacts were persons exposed to the case on or after the day before case diagnostic specimen collection. Contacts were monitored for 14 days after last known exposure. High-risk contacts had close, prolonged case contact (>/=10 minutes within 2 meters). Medium-risk contacts wore all U.S. Centers for Disease Control and Prevention (CDC)-recommended personal protective equipment during interactions. Nasopharyngeal and oropharyngeal (NP/OP) specimens were collected from the case and high-risk contacts and tested for SARS-CoV-2. RESULTS: Paired case NP/OP specimens were collected for SARS-CoV-2 testing at 11 time points. In 8 pairs (73%), >/=1 specimen tested positive or indeterminate, and in 3 pairs (27%) both tested negative. Specimens collected 18 days after diagnosis tested positive. Sixteen contacts were identified; 11 (69%) had high-risk exposure, including 1 intimate contact, and 5 (31%) had medium-risk exposure. In total, 35 high-risk contact NP/OP specimens were collected for SARS-CoV-2 testing; all 35 pairs (100%) tested negative. CONCLUSIONS: This report demonstrates that SARS-CoV-2 infection can cause mild illness and result in positive tests for up to 18 days after diagnosis, without evidence of transmission to close contacts. These data might inform public health strategies to manage individuals with asymptomatic infection or mild illness.

On August 2, 2018, Maricopa County (Arizona) Department of Public Health (MCDPH) identified two isolates of carbapenemase-producing Klebsiella pneumoniae (KPC-KP), a type of carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE), from urine specimens collected on July 17 and July 23 from two residents of a ventilator-capable unit in a skilled nursing facility. CP-CRE are multidrug-resistant organisms typically isolated from persons with a health care exposure (1,2). Invasive CP-CRE infections are associated with a 50% case-fatality rate (3); however, only 31%–63% of asymptomatic carriers are identified with clinical cultures (4,5) and might serve as sources of CP-CRE transmission. Both residents at this skilled nursing facility had indwelling urinary catheters and urinary tract infections, resided in neighboring rooms, and were dependent on nursing care for their activities of daily living; one resident was mechanically ventilated. The Antibiotic Resistance Laboratory Network Mountain Region laboratory in Austin, Texas, performed pulsed-field gel electrophoresis (PFGE) on the two clinical isolates, which were found to have indistinguishable PFGE patterns, suggesting health care–associated transmission. MCDPH and the Arizona Department of Health Services (ADHS) investigated the cluster to prevent additional cases.