Related Clues:
- Cause of many a sick day
- Wintertime ailment
- Reason to stay in bed
- ___ vaccine
- Lacking compassion
- Reason for a shot
- Reason to take a sick day
- Sick-day cause
- It may be avian
- Pandemic disease of 1918
- Bug with its own season
- Yuppie ___ (chronic fatigue syndrome)
- Not at all friendly
- Hard of heart
- Pandemic of 1918