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:

OBJECTIVE: To determine the optimal postponement period for elective surgery in patients with SARS-COV-2 infection. MATERIAL AND METHODS: A multiple-center regional prospective cohort research included patients who underwent elective surgeries in November, 2020. We compared the outcomes in patients with preoperative COVID-19 and those without infection. The primary endpoint was 30-day mortality rate. This parameter was stratified depending on period after COVID-19 diagnosis using logistic regression. RESULTS: Preoperative COVID-19 was diagnosed in 32 (4.6%) out of 682 patients. Thirty-day mortality rate in patients without infection was 1.5%. Preoperative coronavirus infection increased mortality rate (odds ratio 20%, 25%, 18.1% and 8.3% for surgery within 0-2, 3-4, 5-6 and 7-8 weeks after infection, respectively). Surgeries after 7-8 weeks ensured the same result as in patients without infection (odds ratio 1.5%). After 7-8-week postponement of elective surgery, patients with COVID-19 and active symptoms had higher mortality rate compared to those without or resolved symptoms (50 vs. 13 vs 6.5%, respectively). CONCLUSION: If possible, elective surgery should be delayed for at least 7-8 weeks after COVID-19 diagnosis. In patients with active symptoms in 7-8 weeks after diagnosis of infection, further postponement of surgery is recommended.
["Diagnosis", "Prevention"]