<qa>  What is the name of the prophylactic medication that is used within 24 hours of randomization14. Use of prophylactic medications e.g. acetaminophenparacetamol, aspirin, naproxen, or ibuprofen within 24 hours of randomization to prevent or pre-empt symptoms due to vaccination. Subject discovered to have taken a prophylactic medication within the 24 hours prior to planned randomization must be delayed until the 24 hours period is met. 