You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

Emergency department (ED) utilization changed notably during the coronavirus disease 2019 (COVID-19) pandemic in the United States. The purpose of the study was to gain a more thorough understanding of ED patient experience during the early stages of the COVID-19 pandemic. This study used the consensual qualitative approach to analyze open-ended responses from post-ED patient experience surveys from February through July 2020. Comments were included in the analysis if they pertained to care during the pandemic (eg, mentioned "the virus," "masks," "PPE"). A total of 242 COVID-specific comments from 192 unique patients were analyzed (median age 49 years; 69% female). Six themes were identified: visually observed changes, experiences of process changes, expressions of understanding or appreciation, sense of security, COVID-19 disease-specific comments, and "classic" satisfaction comments that align with previous literature on patient experience. The COVID-19 pandemic has challenged health care systems across the world in unique and unprecedented ways. This study identified six themes that better elucidate ED patient experience during an unprecedented public health crisis.
["Prevention"]