Possible Clues:

• Steps to block change producing disease
• Epidemic? Change will involve steps
• Niece slept badly, getting sickness
• Deadly outbreak wants certain steps taken in change
• It'll be the death of me training mum to get to grips with tango
• Change incorporating border access for epidemic
• Case of pure Tamiflu primarily imported to quell epidemic
• Plague caused by coppers covering steps in field
• Steps adopted by coppers in epidemic
• Exercise secrecy about source of terrible disease