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: COVID-19 has seen a series of lockdowns and suspension on non-urgent elective surgeries. Subsequently, there was a drop in the number of diagnostic imaging services billed in April, May, 2020. A survey was undertaken from March to June 2020 to determine the initial impact of COVID-19 on Australasian Sonographers. This article, the first in a 3-part series presents and discusses the results of this survey pertaining to changes in the number of scans performed, and changes in the working hours of sonographers. The remaining two articles in this series address other initial COVID-19 impacts on Australasian Sonographers. Methods: An online survey was conducted containing questions regarding changes to work hours and examination numbers. Results: 444 participants answered the survey. Seventy eight percent of sonographers reported a decrease in the number of examinations being performed in their department A decrease in work hours was reported by 68% of sonographers with almost a quarter of these reporting that they had lost all their hours. A higher percentage of work hours changes were seenin private practices. Many reductions in work hours were reported to be voluntary. Conclusion: Scan numbers in ultrasound departments were affected by COVID-19, as were sonographers' work hours.
["Prevention"]