Related Clues:

• WHO concern
• Wintertime woe
• Major WWI killer
• ''A ___ on you!'' (old curse)
• Cause of many a sick day
• Wintertime ailment
• ''A ___ on thee!''
• Plague's cousin
• Reason to stay in bed
• ___ vaccine
• Reason for a shot
• Reason to take a sick day
• Sick-day cause
• It may be avian
• Pandemic disease of 1918