Possible Clues:

• Sound of spring, for some
• 'Bless you!' trigger
• "Bless you!" prompter
• Cold outburst?
• Sound met with 'Gesundheit!'
• 'Bless you!' preceder
• Outburst from Sneezy
• Sound heard before 'Gesundheit!'
• Blessing lead-in
• "Bless you!" trigger