In this case of receiving miscellaneous income, you would not be eligible to take a deduction for the mileage associated with the income you earned from the Moderna Vaccine Study. You are correct -- it is not business income so you would not file the Schedule C to report it. It would go on your return as "Other Income." If you are eligible to deduct medical expenses I would suggest claiming the mileage as medical mileage on your Schedule A for Itemized Deductions. Otherwise, you would not be able to deduct it at all.
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