Related Clues:

• Fever source
• (The) bug
• Some people are shot because of it
• It can precede the starts of 20- and 58-Across and 11- and 29-Down
• Avian ___
• Why you need a shot in the arm?
• Bird ___
• Avian menace
• Incurable disease
• Common winter bug
• Viral ailment
• One cause of absence
• What some shots prevent
• Common bug
• Like Antarctica