Real world effectiveness of tixagevimab/cilgavimab (Evusheld) in the Omicron era

BACKGROUND

Pre-exposure prophylaxis for COVID-19 with tixagevimab/cilgavimab (T/C) received Emergency Use Authorization (EUA) based on results of a clinical trial conducted prior to the emergence of the Omicron variant. The clinical effectiveness of T/C has not been well described in the Omicron era. We examined the incidence of symptomatic illness and hospitalizations among T/C recipients when Omicron accounted for virtually all local cases.

METHODS

Through retrospective electronic medical record chart review, we identified patients who received T/C between January 1 -July 31, 2022 within our quaternary referral health system. We determined the incidence of symptomatic COVID-19 infections and hospitalizations due to or presumed to be caused by early Omicron variants before and after receiving T/C (pre-T/C and post-T/C). Chi square and Mann-Whitney Wilcoxon two-sample tests were used to examine differences between the characteristics of those who got COVID-19 before or after T/C prophylaxis, and rate ratios (RR) and 95% confidence intervals (CI) were calculated to assess differences in hospitalization rates for the two groups.

RESULTS

Of 1295 T/C recipients, 105 (8.1%) developed symptomatic COVID-19 infection before receiving T/C, and 102 (7.9%) developed symptomatic disease after receiving it. Of the 105 patients who developed symptomatic infection pre-T/C, 26 (24.8%) were hospitalized, compared with six of the 102 patients (5.9%) who were diagnosed with COVID-19 post-T/C (RR = 0.24; 95% CI = 0.10-0.55; p = 0.0002). Seven of the 105 (6.7%) patients infected pre-T/C, but none of the 102 infected post-T/C required ICU care. No COVID-related deaths occurred in either group. The majority of COVID-19 cases among those infected pre-T/C treatment occurred during the Omicron BA.1 surge, while the majority of post-T/C cases occurred when Omicron BA.5 was predominant. In both groups, having at least one dose of vaccine strongly protected against hospitalization (pre-T/C group RR = 0.31, 95% CI = 0.17-0.57, p = 0.02; post-T/C group RR = 0.15; 95% CI = 0.03-0.94; p = 0.04).

CONCLUSION

We identified COVID-19 infections after T/C prophylaxis. Among patients who received T/C at our institution, COVID-19 Omicron cases occurring after T/C were one-fourth as likely to require hospitalization compared to those with Omicron prior to T/C. However, due to the presence of changing vaccine coverage, multiple therapies, and changing variants, the effectiveness of T/C in the Omicron era remains difficult to assess.

499. Infection with Coronavirus Disease 19 (COVID-19) in Healthcare Personnel with Exposure to COVID-19

Background

As of June 2, 2020, 67,113 cases and 321 deaths due to Coronavirus Disease 19 (COVID-19) have been reported in healthcare personnel (HCP) in the United States. Given the close contact of HCP with individuals with COVID-19, it is important to quantify the risk of acquiring COVID-19 in the healthcare setting.

Methods

We conducted a retrospective cohort study of HCP exposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at our academic medical center from March 15, 2020 to May 16, 2020. Exposure during the study period was defined as having contact with patients or other HCP with COVID-19 within 6 feet of distance for at least 90 seconds when HCP’s eyes, nose, or mouth were not covered. HCP with exposures were monitored for symptoms consistent with COVID-19 for 14 days from last exposure and those who developed symptoms were tested for SARS-CoV-2 using RT-PCR.

Results

We identified 33 exposure events; 19 of which were patient-to-HCP exposures and 14 of which were HCP-to-HCP exposures. These 33 events resulted in 959 exposed HCP among whom 238 (25%) developed one or more symptoms of COVID-19 and required SARS-CoV-2 RT-PCR testing. Testing was performed at 7.1 ± 5.0 (mean ± SD) days from exposure. Of the 238 HCP who were tested, 82% were female and 49% were registered nurses (Table 1). Five HCP tested positive for SARS-CoV-2 by RT-PCR, but one was presumed to have acquired the disease from a household member with confirmed COVID-19. Among the four HCP who were infected due to occupational exposure, three were nurses while one was an environmental service worker (Table 1).

Conclusion

Despite exposures among HCP, the risk of acquiring symptomatic COVID-19 in the healthcare setting was low with less than 1% of HCP with occupational exposure subsequently diagnosed with COVID-19. With the definition of exposure now changed to at least 15 minutes of close contact without personal protective equipment, we anticipate fewer exposures at our healthcare facility and that much of COVID-19 transmission affecting HCP are due to community exposures.

Disclosures

All Authors: No reported disclosures

374. Complication with Bacterial Pneumonia in Hospitalized Patients with Coronavirus Disease 2019 (COVID-19)

Background

Early reports have indicated widespread empiric antimicrobial usage in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As data regarding bacterial complications in patients with Coronavirus Disease 2019 (COVID-19) are limited and emerging, it is important to delineate the burden of complications with bacterial pneumonia in patients with COVID-19 and its implication on antimicrobial usage.

Methods

We conducted a retrospective cohort study of all hospitalized patients diagnosed with COVID-19 based on detection of SARS-CoV-2 on RT-PCR from March 1, 2020 to May 10, 2020. Data were collected retrospectively to determine the presence of bacterial pneumonia among patients hospitalized with COVID-19 and to identify demographics, comorbidities, or laboratory values that may help to distinguish patients with bacterial pneumonia. Fisher’s exact test was used to analyze categorical data and Student’s t test was used to analyze differences between means.

Results

Among 99 patients hospitalized with COVID-19 during the study period, complication with bacterial pneumonia was seen in 17 (17%) based on sputum, tracheal aspirate or lower respiratory tract cultures performed 8.9 ± 7.8 (mean ± SD) days from the detection of SARS-CoV-2 on RT-PCR. Staphylococcus aureus was the causative organism in 8 (47%) cases while Enterobacteriaceae were isolated in 7 (41%) cases, Burkholderia cepacia in one (6%) and Rahnella aqualitis in one (6%) case. There were no significant differences in demographics, comorbidities, or laboratory findings between patients with or without complication with bacterial pneumonia. However, those with complication with bacterial pneumonia were more likely to be intubated (24% vs. 88%, p< 0.01), on vasopressors (23% vs. 82%, p < 0.01), and require intensive care unit admission (37% vs. 94%, p< 0.01).

Conclusion

Nosocomial and ventilator-associated pneumonia were commonly seen among hospitalized patients with COVID-19 requiring intubation and intensive care use admission. With complications of bacterial pneumonia common among critically-ill patients infected with SARS-CoV-2, widespread antimicrobial usage may increase the selective pressure for antibiotic resistance in this patient population.

Disclosures

All Authors: No reported disclosures

Rapid response to COVID-19: health informatics support for outbreak management in an academic health system

OBJECTIVE

To describe the implementation of technological support important for optimizing clinical management of the COVID-19 pandemic.

MATERIALS AND METHODS

Our health system has confirmed prior and current cases of COVID-19. An Incident Command Center was established early in the crisis and helped identify electronic health record (EHR)-based tools to support clinical care.

RESULTS

We outline the design and implementation of EHR-based rapid screening processes, laboratory testing, clinical decision support, reporting tools, and patient-facing technology related to COVID-19.

DISCUSSION

The EHR is a useful tool to enable rapid deployment of standardized processes. UC San Diego Health built multiple COVID-19-specific tools to support outbreak management, including scripted triaging, electronic check-in, standard ordering and documentation, secure messaging, real-time data analytics, and telemedicine capabilities. Challenges included the need to frequently adjust build to meet rapidly evolving requirements, communication, and adoption, and to coordinate the needs of multiple stakeholders while maintaining high-quality, prepandemic medical care.

CONCLUSION

The EHR is an essential tool in supporting the clinical needs of a health system managing the COVID-19 pandemic.

2101. Impact of “Code Sepsis” on Antimicrobial Utilization at an Academic Medical Center

Background

Balancing antimicrobial stewardship with sepsis management is a challenge. At our academic medical center, a “Code Sepsis” was implemented as a nursing driven initiative to improve early recognition and management of sepsis. Per protocol, Code Sepsis is activated in patients who meet two or more systemic inflammatory response syndrome (SIRS) criteria due to a suspected infection to allow for early implementation of the sepsis bundle, which includes laboratory testing, fluid resuscitation, and antibiotic administration (Figure 1). We analyzed the impact that Code Sepsis had on antimicrobial use among hospitalized patients over a six month period.

Methods

We reviewed the electronic medical records of hospitalized patients with Code Sepsis activation between January 1, 2018 and June 30, 2018 to determine whether antibiotics were “escalated” or “not escalated.” Among patients who had antibiotic escalation, escalation was classified as “indicated” or “not indicated” (Figure 2). A logistic regression model was used to identify characteristics, SIRS or organ dysfunction criteria predictive of indicated antimicrobial escalation.

Results

Code Sepsis was activated in 529 patients with antibiotics escalated in 247 (47%) and not escalated in 282 (53%) (Table 1). Among patients whose antibiotics were escalated, 64% (152) had an indication. In 36% (89), escalation was not indicated as Code Sepsis was due to a suspected noninfectious source, known infectious source already on appropriate antimicrobials, or a suspected infectious source in which diagnostic results had already shown the absence of the infection (Figure 2). Odds of indicated antibiotic escalation increased with the number of SIRS and organ dysfunction criteria (Table 2).

Conclusion

In our efforts to improve sepsis outcomes, we focused on early recognition (Code Sepsis) and intervention (sepsis bundle). However, our Code Sepsis inadvertently led to antibiotic overutilization. By refocusing Code Sepsis on early recognition of severe sepsis and septic shock, we hope to optimize resource utilization and improve patient outcomes.

Disclosures

All authors: No reported disclosures.

Case Report: A Common Source Outbreak of Anisakidosis in the United States and Postexposure Prophylaxis of Family Collaterals

We present a case of intussusception with complete small bowel obstruction caused by intestinal anisakidosis requiring surgical resection. A 30-year-old man presented with acute onset of severe abdominal pain 3 days after eating home-cured salmon gravlax. Despite surgery, the patient developed recurrent abdominal pain on two occasions with evidence of continued inflammation proximal to the surgical anastomosis. He was then treated with albendazole and prednisone, and symptoms improved. A decision was made to prophylactically treat two asymptomatic family members who also consumed home-cured gravlax with albendazole, resulting in one individual passing an intact Anisakis worm in her stool. We suggest that albendazole therapy could be considered as a therapy for continued symptoms of anisakidosis and postexposure prophylaxis of Anisakis larvae ingestion from a common source.

Whole genome sequencing analysis of Plasmodium vivax using whole genome capture

Background

Malaria caused by Plasmodium vivax is an experimentally neglected severe disease with a substantial burden on human health. Because of technical limitations, little is known about the biology of this important human pathogen. Whole genome analysis methods on patient-derived material are thus likely to have a substantial impact on our understanding of P. vivax pathogenesis and epidemiology. For example, it will allow study of the evolution and population biology of the parasite, allow parasite transmission patterns to be characterized, and may facilitate the identification of new drug resistance genes. Because parasitemias are typically low and the parasite cannot be readily cultured, on-site leukocyte depletion of blood samples is typically needed to remove human DNA that may be 1000X more abundant than parasite DNA. These features have precluded the analysis of archived blood samples and require the presence of laboratories in close proximity to the collection of field samples for optimal pre-cryopreservation sample preparation.

Results

Here we show that in-solution hybridization capture can be used to extract P. vivax DNA from human contaminating DNA in the laboratory without the need for on-site leukocyte filtration. Using a whole genome capture method, we were able to enrich P. vivax DNA from bulk genomic DNA from less than 0.5% to a median of 55% (range 20%-80%). This level of enrichment allows for efficient analysis of the samples by whole genome sequencing and does not introduce any gross biases into the data. With this method, we obtained greater than 5X coverage across 93% of the P. vivax genome for four P. vivax strains from Iquitos, Peru, which is similar to our results using leukocyte filtration (greater than 5X coverage across 96% ).

Conclusion

The whole genome capture technique will enable more efficient whole genome analysis of P. vivax from a larger geographic region and from valuable archived sample collections.

Amazonian malaria: asymptomatic human reservoirs, diagnostic challenges, environmentally driven changes in mosquito vector populations, and the mandate for sustainable control strategies

Across the Americas and the Caribbean, nearly 561,000 slide-confirmed malaria infections were reported officially in 2008. The nine Amazonian countries accounted for 89% of these infections; Brazil and Peru alone contributed 56% and 7% of them, respectively. Local populations of the relatively neglected parasite Plasmodium vivax, which currently accounts for 77% of the regional malaria burden, are extremely diverse genetically and geographically structured. At a time when malaria elimination is placed on the public health agenda of several endemic countries, it remains unclear why malaria proved so difficult to control in areas of relatively low levels of transmission such as the Amazon Basin. We hypothesize that asymptomatic parasite carriage and massive environmental changes that affect vector abundance and behavior are major contributors to malaria transmission in epidemiologically diverse areas across the Amazon Basin. Here we review available data supporting this hypothesis and discuss their implications for current and future malaria intervention policies in the region. Given that locally generated scientific evidence is urgently required to support malaria control interventions in Amazonia, we briefly describe the aims of our current field-oriented malaria research in rural villages and gold-mining enclaves in Peru and a recently opened agricultural settlement in Brazil.

Socio-demographics and the development of malaria elimination strategies in the low transmission setting

This analysis presents a comprehensive description of malaria burden and risk factors in Peruvian Amazon villages where malaria transmission is hypoendemic. More than 9000 subjects were studied in contrasting village settings within the Department of Loreto, Peru, where most malaria occurs in the country. Plasmodium vivax is responsible for more than 75% of malaria cases; severe disease from any form of malaria is uncommon and death rare. The association between lifetime malaria episodes and individual and household covariates was studied using polychotomous logistic regression analysis, assessing effects on odds of some vs. no lifetime malaria episodes. Malaria morbidity during lifetime was strongly associated with age, logging, farming, travel history, and living with a logger or agriculturist. Select groups of adults, particularly loggers and agriculturists acquire multiple malaria infections in transmission settings outside of the main domicile, and may be mobile human reservoirs by which malaria parasites move within and between micro-regions within malaria endemic settings. For example, such individuals might well be reservoirs of transmission by introducing or reintroducing malaria into their home villages and their own households, depending on vector ecology and the local village setting. Therefore, socio-demographic studies can identify people with the epidemiological characteristic of transmission risk, and these individuals would be prime targets against which to deploy transmission blocking strategies along with insecticide treated bednets and chemoprophylaxis.

Longitudinal distribution of ozone absorption in the lung: simulation with a single-path model

A one-dimensional unsteady state diffusion model was used as a basis for simulating the absorption (lambda), breakthrough (V(B)), and dispersion (sigma2) of inhaled ozone boluses as a function of penetration (V(P)) into intact human lungs. The model idealized the respiratory system as a single equivalent tube with cross-sectional and surface areas that varied as a function of longitudinal position. Longitudinal gas transport in the lumen of the equivalent tube occurred by the joint action of bulk flow and a dispersion coefficient, D. Lateral absorption between respired gas and the tube wall was characterized by an overall mass transfer coefficient, K. By inputting published values of anatomic dimensions scaled to a 160-ml conducting airway volume, D values previously reported for inert insoluble gases, and K values equal to gas-phase transfer coefficients determined in physical lung models, a reasonable simulation of the lambda-V(P) distribution measured at a 250 ml/sec respiratory flow was obtained. Simulations of the corresponding V(B)-V(P) and sigma2-V(P) distributions both exhibited the correct shapes but underestimated the actual values. Although the addition of an estimated tissue resistance to K resulted in a poorer simulation of the data, an increase in conducting airway volume from a value of 160 ml estimated by the subjects' CO2 dead space to a value of 200 ml substantially improved the V(B)-V(P) and sigma2-V(P) simulations without sacrificing the quality of the lambda-V(P) simulation. We conclude that the inclusion of a tissue diffusion resistance is not necessary to properly simulate bolus inhalation data during quiet breathing, but a reliable measurement of conducting airway volume is crucial.