Yes, a movie. Not OVA, not animated, a movie. Motion picture.
It's about a base on Antartica or somewhere like that and they find an alien pod. An alien comes out and people and plants start dying.
It is later revealed that the alien is not hostile, just EXTREMELY toxic to Earth life and the Earth Goverments know about that (not an evil goverment).
In the end they nuke the arctic base because that's what they did before as well, they nuked the contamination site. I think of the characters leaves with aliens or something as well.