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:

Aim: We investigated the effect of pre-analytical sample handling variations on coronavirus disease 2019-relevant circulating cytokine levels IFN-gamma, IL-10, IL-12p70, IL-17A, IL-6 and TNF-alpha. Materials & methods: We collected blood in different collection tubes (ethylenediaminetetraacetic acid, sodium citrate, lithium heparin, serum), and subjected ethylenediaminetetraacetic acid plasma to among others increasing delays in centrifugation or -80 degrees C storage. Six subjects were included in each experimental condition. Cytokine levels were measured in these samples using the Simoa Cytokine 6-plex kit. Results: Different tube types resulted in different blood cytokine levels. IL-17A and IL-6 levels declined with 3 h centrifugation delay. IFN-gamma levels declined with 24 h postcentrifugation storage delay. IL-17A levels declined with 2-week storage delay. Conclusion: It is recommended to centrifuge tubes quickly following collection, for accurate cytokine measurement.
["Diagnosis"]