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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 6251 publications in this collection, published between 2000 and 2023.
Open Access Policy Deposits (433)

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 (coronavirus disease) pandemic. However, the mask adoption rate in the United States 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 U.S.-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 a 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.


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.

Curating the Digital Mental Health Landscape With a Guide to Behavioral Health Apps: A County-Driven Resource.

With more than 10,000 mental health apps available, consumers and clinicians who want to adopt such tools can be overwhelmed by the multitude of options and lack of clear evaluative standards. Despite the increasing prevalence of curated lists, or app guides, challenges remain. Organizations providing mental health services to consumers have an opportunity to address these challenges by producing guides that meet relevant standards of quality and are tailored to local needs. This column summarizes an example of the collaborative process of app guide development in a publicly funded mental health service context and highlights opportunities and barriers identified through the process.

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