SARS-CoV-2 Infection and Hospitalization Among Adults Aged ≥18 Years, by Vaccination Status, Before and During SARS-CoV-2 B.1.1.529 (Omicron) Variant Predominance - Los Angeles County, California, November 7, 2021-January 8, 2022.

COVID-19 vaccines are effective at preventing infection with SARS-CoV-2, the virus that causes COVID-19, as well as severe COVID-19-associated outcomes in real-world conditions (1,2). The risks for SARS-CoV-2 infection and COVID-19-associated hospitalization are lower among fully vaccinated than among unvaccinated persons; this reduction is even more pronounced among those who have received additional or booster doses (boosters) (3,4). Although the B.1.1.529 (Omicron) variant spreads more rapidly than did earlier SARS-CoV-2 variants, recent studies suggest that disease severity is lower for Omicron compared with that associated with the B.1.617.2 (Delta) variant; but the high volume of infections is straining the health care system more than did previous waves (5).*,† The Los Angeles County (LAC) Department of Public Health (LACDPH) used COVID-19 surveillance and California Immunization Registry 2 (CAIR2) data to describe age-adjusted 14-day cumulative incidence and hospitalization rates during November 7, 2021-January 8, 2022, by COVID-19 vaccination status and variant predominance. For the 14-day period ending December 11, 2021, the last week of Delta predominance, the incidence and hospitalization rates among unvaccinated persons were 12.3 and 83.0 times, respectively, those of fully vaccinated persons with a booster and 3.8 and 12.9 times, respectively, those of fully vaccinated persons without a booster. These rate ratios were lower during Omicron predominance (week ending January 8, 2022), with unvaccinated persons having infection and hospitalization rates 3.6 and 23.0 times, respectively, those of fully vaccinated persons with a booster and 2.0 and 5.3 times, respectively, those of fully vaccinated persons without a booster. In addition, during the entire analytic period, admission to intensive care units (ICUs), intubation for mechanical ventilation, and death were more likely to occur among unvaccinated persons than among fully vaccinated persons without or with a booster (p<0.001). Incidence and hospitalization rates were consistently highest for unvaccinated persons and lowest for fully vaccinated persons with a booster. Being up to date with COVID-19 vaccination is critical to protecting against SARS-CoV-2 infection and associated hospitalization.

Seroprevalence of Severe Acute Respiratory Syndrome Coronavirus 2 Among Skilled Nursing Facility Residents and Staff Members-Los Angeles County, August-September 2020.

BACKGROUND: The prevalence of current or past coronavirus disease 2019 in skilled nursing facility (SNF) residents is unknown because of asymptomatic infection and constrained testing capacity early in the pandemic. We conducted a seroprevalence survey to determine a more comprehensive prevalence of past coronavirus disease 2019 in Los Angeles County SNF residents and staff members. METHODS: We recruited participants from 24 facilities; participants were requested to submit a nasopharyngeal swab sample for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) testing and a serum sample for detection of SARS-CoV-2 antibodies. All participants were cross-referenced with our surveillance database to identify persons with prior positive SARS-CoV-2 results. RESULTS: From 18 August to 24 September 2020, we enrolled 3305 participants (1340 residents and 1965 staff members). Among 856 residents providing serum samples, 362 (42%) had current or past SARS-CoV-2 infection. Of the 346 serology-positive residents, 199 (58%) did not have a documented prior positive SARS-CoV-2 PCR result. Among 1806 staff members providing serum, 454 (25%) had current or past SARS-CoV-2 infection. Of the 447 serology-positive staff members, 353 (79%) did not have a documented prior positive SARS-CoV-2 PCR result. CONCLUSIONS: Past testing practices and policies missed a substantial number of SARS-CoV-2 infections in SNF residents and staff members.

Incidentally Detected SARS-COV-2 Among Hospitalized Patients in Los Angeles County, August to October 2020.

We aimed to determine the percentage of COVID-19- associated hospitalizations reported to Los Angeles County (LAC) Public Health that might have been misclassified because of incidentally detected SARS-CoV-2. We retrospectively reviewed medical records from a randomly selected set of hospital discharges reported to LAC Public Health from August to October 2020 for a clinical diagnosis of COVID-19 or a positive SARS-CoV-2 test result. Among the 13,813 discharges from 85 hospitals reported to LAC Public Health as COVID-19-associated hospitalizations from August to October 2020, 346 were randomly selected and reviewed. SARS-CoV-2 detection was incidental to the reason for hospitalization in 12% (95% confidence limit, 9%-16%) of COVID-19 classified hospital discharges. Adjusting COVID-19-associated hospitalization rates to account for incidental SARS-CoV-2 detection could help public health policymakers and emergency preparedness personnel improve resource planning.

Diagnostic Performance of an Antigen Test with RT-PCR for the Detection of SARS-CoV-2 in a Hospital Setting - Los Angeles County, California, June-August 2020.

Prompt and accurate detection of SARS-CoV-2, the virus that causes COVID-19, has been important during public health responses for containing the spread of COVID-19, including in hospital settings (1-3). In vitro diagnostic nucleic acid amplification tests (NAAT), such as real-time reverse transcription-polymerase chain reaction (RT-PCR) can be expensive, have relatively long turnaround times, and require experienced laboratory personnel.* Antigen detection tests can be rapidly and more easily performed and are less expensive. The performance† of antigen detection tests, compared with that of NAATs, is an area of interest for the rapid diagnosis of SARS-CoV-2 infection. The Quidel Sofia 2 SARS Antigen Fluorescent Immunoassay (FIA) (Quidel Corporation) received Food and Drug Administration Emergency Use Authorization for use in symptomatic patients within 5 days of symptom onset (4). The reported test positive percentage agreement§ between this test and an RT-PCR test result is 96.7% (95% confidence interval [CI] = 83.3%-99.4%), and the negative percentage agreement is 100.0% (95% CI = 97.9%-100.0%) in symptomatic patients.¶ However, performance in asymptomatic persons in a university setting has shown lower sensitivity (5); assessment of performance in a clinical setting is ongoing. Data collected during June 30-August 31, 2020, were analyzed to compare antigen test performance with that of RT-PCR in a hospital setting. Among 1,732 paired samples from asymptomatic patients, the antigen test sensitivity was 60.5%, and specificity was 99.5% when compared with RT-PCR. Among 307 symptomatic persons, sensitivity and specificity were 72.1% and 98.7%, respectively. Health care providers must remain aware of the lower sensitivity of this test among asymptomatic and symptomatic persons and consider confirmatory NAAT testing in high-prevalence settings because a false-negative result might lead to failures in infection control and prevention practices and cause delays in diagnosis, isolation, and treatment.

Influenza Vaccination Coverage of Health Care Personnel in Los Angeles County Hospitals, 2016-2017.

The objective of the Los Angeles County, California (LAC), health care personnel (HCP) influenza vaccination improvement intervention was to increase HCP influenza vaccination coverage during the 2016-2017 influenza season via targeted outreach to LAC acute care hospitals. We selected 13 facilities for intervention and received tailored recommendations from a menu of evidence-based practices. Following the season, each hospital in the intervention group experienced a significant increase in vaccination coverage, which increased the LAC countywide average for all hospitals by 5%, from 74% to 79%.

Understanding Infection Prevention Practices in Optometry Clinics.

SIGNIFICANCE: The Los Angeles County Department of Public Health investigated an outbreak of epidemic keratoconjunctivitis secondary to adenovirus linked to a single optometry clinic between June and July 2017. Suboptimal infection prevention practices were identified in the implicated clinic. PURPOSE: The purpose of this study was to determine infection prevention practices in optometry clinics within Los Angeles County. METHODS: A 17-question survey on infection prevention practices among a sample of optometry providers in the county was conducted by the Los Angeles County Department of Public Health. The survey was administered via e-mails sent to a local optometric society's Listserv and in person at a local continuing education event for optometrists. The results were analyzed and are represented as percentages. RESULTS: There were 42 responses, 20 via the online survey (response rate, 15%) and 22 via the in-person survey (response rate, 22%). More than half had no written hand-hygiene policy (58.5%, n = 24/41), 46.2% (n = 18/39) did not wear gloves while examining patients with eye drainage, and about half (48.6%, n = 18/37) did not use droplet precautions for patients with respiratory symptoms. The vast majority used multidose eye-drop vials (92.5%, n = 37/40), but 41.6% (n = 15/36) did not discard the vial if the tip came into contact with conjunctiva/skin/environmental surface. To ensure a clean tonometer for each patient, the majority (68.4%, n = 26/38) used 70% isopropyl alcohol, 47.4% (n = 18/38) used noncontact tonometers, and 23.6% (n = 9/38) used disposable tips (answers not mutually exclusive); none used bleach. CONCLUSIONS: Our data highlight several areas of concern in the practice of standard or transmission-based precautions in the sampled population. First, hand-hygiene policies are not well enforced. Second, personal protective equipment is not appropriately used while examining potentially infectious patients. Third, eye-drop vials are not consistently discarded if contaminated with eye secretions. Lastly, a large proportion of surveyed practices use inadequate disinfection techniques of tonometers.

A Multidisciplinary Approach to Incorporate Bedside Nurses into Antimicrobial Stewardship and Infection Prevention.

BACKGROUND: Antimicrobial stewardship programs exist to promote appropriate antimicrobial use. The Joint Commission has reported that although many US hospitals have implemented basic components of antimicrobial stewardship programs, there now exists a need for innovative, multidisciplinary approaches, including involving frontline clinicians such as bedside nurses. METHODS: A retrospective evaluation of bedside nurse-driven antimicrobial stewardship and infection prevention rounds was conducted on a 31-bed telemetry unit of a community regional medical center. Rounds were managed by a nurse coordinator and attended by an infectious diseases pharmacist, an infection preventionist, and a nurse practitioner. Primary outcome measures were antimicrobial and acid suppressant medication and invasive catheter use. RESULTS: In the 12-month intervention period the nurse-driven rounds team reviewed of a total of 472 antimicrobial medication, 480 acid suppressant medication, 321 urinary catheter, and 61 central venous catheter therapies over 867 total patient encounters. Compared with the 12-month preintervention period, significant reductions in unit antimicrobial use (791.2 vs. 697.1 days of therapy per 1,000 patient-days; p = 0.03), acid suppressant medication use (708.1 vs. 372.4 days of therapy per 1,000 patient-days; p = 0.0001), and urinary catheter use (0.3 vs. 0.2 catheter-days per patient-day; p = 0.002) were observed. CONCLUSION: This study demonstrates successful engagement of bedside nurses in antimicrobial stewardship and infection prevention activities and a measurable impact on meaningful outcomes. More studies of strategies to integrate bedside nurses in antimicrobial stewardship are needed.

Outbreak of Epidemic Keratoconjunctivitis Caused by Human Adenovirus Type D53 in an Eye Care Clinic - Los Angeles County, 2017.

On June 22, 2017, the Los Angeles County Department of Public Health (LAC DPH) was notified of seven patients who were seen at an eye care clinic on June 8, 2017, and later developed symptoms of epidemic keratoconjunctivitis (EKC). EKC is a contagious, severe form of viral conjunctivitis that can cause pain and blurred vision for up to 4 weeks (1). LAC DPH conducted an investigation, which identified 17 patients with EKC, including 15 who had visited the optometry clinic and two who were household contacts of clinic patients. Observations in the clinic found deficiencies in disinfection of tonometers (an instrument connected to a slit lamp and used to test for glaucoma by measuring intraocular pressure) and multiuse eye drop administration. Staff member education and revision of disinfection practices interrupted further transmission. Patient specimens tested positive for human adenovirus (HAdV) type D53 (HAdV-53). As the first documented EKC outbreak associated with HAdV-D53 in the United States, this outbreak highlights the need for rigorous implementation of recommended infection prevention practices in eye care settings.

Health Care-Associated Infection Outbreak Investigations in Outpatient Settings, Los Angeles County, California, USA, 2000-2012.

Health care services are increasingly delivered in outpatient settings. However, infection control oversight in outpatient settings to ensure patient safety has not improved and literature quantifying reported health care-associated infection outbreaks in outpatient settings is scarce. The objective of this analysis was to characterize investigations of suspected and confirmed outbreaks in outpatient settings in Los Angeles County, California, USA, reported during 2000-2012, by using internal logs; publications; records; and correspondence of outbreak investigations by characteristics of the setting, number, and type of infection control breaches found during investigations, outcomes of cases, and public health responses. Twenty-eight investigations met the inclusion criteria. Investigations occurred frequently, in diverse settings, and required substantial public health resources. Most outpatient settings investigated had >1 infection control breach. Lapses in infection control were suspected to be the outbreak source for 16 of the reviewed investigations.

Outbreak of bloodstream infections associated with multiuse dialyzers containing O-rings.

This report details an outbreak investigation conducted by the Los Angeles County Department of Public Health of 3 cases of bacterial infection among patients receiving hemodialysis who were treated at the same dialysis center in 2011. Improper disinfection of reusable dialyzers was hypothesized as the source of transmission.