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:

INTRODUCTION: Severe COVID-19 is associated with hypoxemic bilateral pneumonia that leads to mechanical ventilation in a considerable proportion of patients. To the best of our knowledge, there are no recommendations about the best time to initiate high flow nasal cannula (HFNC). PATIENTS AND METHODS: Retrospective study of all patients admitted for COVID-19 pneumonia who required HNFO between March 2020 and February 2021. Patients were grouped in early HNFC or late HNFC, according to the modified Kirby index. RESULTS: 53 patients were included. Forty-four of them were included in the early HFNC and 9 in late HNFC. There were no statistically significant clinical-epidemiological differences. Early use of HFNC was associated with a decrease in the need for intubation (29.5 vs. 66.6%, p = 0.044), hospital stay (18.8 d vs. 36 d, p = 0.022) and mortality (22.7 vs. 55.5%, p = 0.061). CONCLUSIONS: Early HFNC use is associated with a decrease in the need for intubation, mortality and overall hospital stay.
["Treatment", "Diagnosis"]