Just a new take on the 'Ghost Ship' theme...
I just see this movie as being a "mix-n-match" of old ideas, to freshen up the old recipe of the "Ghost Ship" theme. Think of it this way... They had already done the theme with supernatural monsters, and they wanted something more catchy... Not to mention that there had been a similar movie less than 2 years before!
So, what was catchy in 1999? Aliens, of course! So the guys behind the creation of this movie thought, hey, let's put an abandoned ship somewhere in the sea. And say, instead of being butchered by ghosts or supernatural creatures... Why not have aliens on board? There you go, the entire plot of this totally cheesy movie (IMHO, of course).
See other movies like it:
Ghost Ship (2002)
Haunted Sea (1997), aka "Ghost Ship"
Ghost Ship (1992)
Ghost Ship (1952)
Also, I don't think it's any coincidence that Joanna Pacula is in this film. She was among the cast of the "Haunted Sea" movie.
The only originality (a much-needed thing), was that they didn't call the movie Ghost Ship. Probably because there was no GHOSTS... And "Alien Ship" would have sucked. So, let's give away the punch and call it the main thing, that HUMANS are a VIRUS! (Come to think of it, people creating such harebrained movies and still manage to create MORE movies should be called VIRUSES).