Is this a concern for providers/hobbyists? I know there's some providers known for DFK'ing, and this is supposedly the worst flu season ever.

not an enteral illness. It is spread by respiratory secretions: nasal mucous and lung sputum. Kissing has little if anything to do with transmission. If you want to avoid influenza, you need to avoid breathing the same air as an infected person is breathing/coughing/sneezing into. Pretty much the same goes for the common cold.

Strep, OTOH, is the exact opposite. Hope this helps.

and don't plan on it .
If you're sick or think you might be stay home! That's all I can say.

It's not a guarantee but is the best way to protect yourself.

I'd think it would take some skill to DFK without breathing the same air the person you're kissing is breathing…