Undercurrent used in a sentence

Undercurrent in a sentence as a noun

There's a sad undercurrent to this, as some redditors respond that they find this depressing.

It's a disgrace that a country as large and dominant as the US cannot take care of it's own. I honestly believe that the healthcare situation adds a strong undercurrent of stress to everyone's lives here in the US.

I can assure you that an undercurrent of socioeconomically-associated racism still exists in large swathes of the US where there are significant black and Hispanic populations.