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Open Access Publications from the University of California


The Department of Emergency Medicine in the University of California (UC), Irvine School of Medicine has 15 full-time faculty members specializing in disaster and public health preparedness, emergency medical services, infectious disease, informatics, injury prevention, international emergency medicine, medical education, pediatrics, public health, toxicology, and ultrasound, The Department has a highly ranked three year emergency medicine residency training program fully accredited since 1989. UC Irvine Medical Center, a 400 bed full-service university hospital is the primary teaching center for the UC Irvine School of Medicine. The UC Irvine Medical Center is the only Level I Trauma Center and Burn Center in Orange County, treating approximately 2,200 trauma and 44,000 medical patients annually.

Department of Emergency Medicine (UCI)

There are 4812 publications in this collection, published between 2000 and 2021.
Open Access Policy Deposits (212)

Why do people oppose mask wearing? A comprehensive analysis of US tweets during the COVID-19 pandemic.


Facial masks are an essential personal protective measure to fight the COVID-19 pandemic. However, the mask adoption rate in the US is still less than optimal. This study aims to understand the beliefs held by individuals who oppose the use of facial masks, and the evidence that they use to support these beliefs, to inform the development of targeted public health communication strategies.

Materials and methods

We analyzed a total of 771,268 US-based tweets between January to October 2020. We developed machine-learning classifiers to identify and categorize relevant tweets, followed by a qualitative content analysis of a subset of the tweets to understand the rationale of those opposed mask wearing.


We identified 267,152 tweets that contained personal opinions about wearing facial masks to prevent the spread of COVID-19. While the majority of the tweets supported mask wearing, the proportion of anti-mask tweets stayed constant at about 10% level throughout the study period. Common reasons for opposition included physical discomfort and negative effects, lack of effectiveness, and being unnecessary or inappropriate for certain people or under certain circumstances. The opposing tweets were significantly less likely to cite external sources of information such as public health agencies' websites to support the arguments.

Discussion and conclusion

Combining machine learning and qualitative content analysis is an effective strategy for identifying public attitudes toward mask wearing and the reasons for opposition. The results may inform better communication strategies to improve the public perception of wearing masks and, in particular, to specifically address common anti-mask beliefs.

Ultrasound-guided central venous access: which probe is preferred for viewing the subclavian vein using a supraclavicular approach?


Point-of-care ultrasound guidance using a linear probe is well established as a tool to increase safety when performing a supradiaphragmatic cannulation of the internal jugular central vein. However, little data exist on which probe is best for performing a supradiaphragmatic cannulation of the subclavian vein.


This was a prospective, observational study at a single-site emergency department, where 5 different physician sonologists evaluate individual practice preference for visualization of the subclavian vein using a supraclavicular approach with 2 different linear probes and 1 endocavitary probe.


Of 155 patients enrolled, there was no clear preference any of the probes (P= .03). After pooling linear probe preference, there was a preference for either linear probe over the alternative endocavitary probe (76.8% vs 23.1%, P< .05).


We observed a preference for a linear probe over an endocavitary probe. Further investigation is necessary to determine which probe is optimal for this application.

Race-related Healthcare Disparities Among California Workers: Public Health Considerations for Immigration Reform.


Healthcare disparities are prevalent in medicine and identifying them will provide healthcare professionals, administrators, and policy makers needed information to address this public health concern.


To evaluate racial and ethnic disparities in the rates of hospital admission and death among California workers.


We performed an analysis of hospital and emergency department (ED) data from the Office of Statewide Health Planning and Development (OSHPD). Data was collected from California licensed acute care hospitals from 2008-2010.

Inclusion criteria

patients >15 years of age whose expected source of payment was worker's compensation.

Exclusion criteria

patients <15 years; had missing data for age, sex, race, or injury; or were injured by a suicide attempt, poisoning, or complication of medical procedure. Multivariate logistic regression was used to evaluate the relationship of race/ethnicity and admission/death rates.


There were 393,298 patients discharged from the ED and 23,343 patients admitted from ED had workers compensation as their expected sources of payment and 150,277 met our inclusion criteria. The annual rate of ED treated injuries was 209/100,000 for Caucasians 343/100,000 for Hispanics, 258/100,000 for blacks and 97/100,000 for Asians. Compared to Caucasians, admission odds ratios (OR) were 1.15 (95% CI 1.07-1.25) for Hispanics, 1.08 (95% CI 0.87-1.33) for blacks, and 0.78 (95% CI 0.63-0.97) for Asians.


We observed race and ethnicity related healthcare disparities among the occupationally injured in California, with Hispanics having the highest odds of admission and annual incidence of ED treated injuries. No difference in mortality rates was observed.

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