The danger close perk is much like the perk in other installments of the series, increases explosive damage.

My question is does it affect all explosions or simply ones from grenades/launchers.

Example, (and my main question) does it affect the NA-45's special effect? How about things that aren't controlled by you, like streak rewards?

2 Answers

I don't have the official information, so I'm going to give you my opinion and that of a trusted youtuber : I think it affects all of explosions that you cause directly (grenades, launchers, NA-45 but not killstreak bonuses, like planes or assault drones even controlled ones).

For the NA-45, I didn't test it but youtuber Drift0r who usually tests everything advices to use it (source).

It does say in the perk description (in game) that it increases the effects of explosions and scorestreaks. I've heard that it increases the damage of explosions by 10%, I would expect that it does the same with damage dealt by scorestreaks.