What is it?
The 1987 science fiction / horror anime movie Lily C.A.T..
https://fantasyanime.com/anime/lily-cat-dub
What is it about?
This is how Anime News Network describes this movie:
A crew travels across the universe in a ship that can travel for 20 years while the crew will age only 1 year.
Suddenly some of the crew members are coming down with some sort of virus.
With no help from the outside world can the crew survive this viral attack for a year.
John Jr's Blog 