Is it true that is the annihilation movie just the first book based on the following text?

In March 2013, it was announced that Paramount Pictures and Scott Rudin Productions had acquired the film rights to Annihilation, the first novel in Jeff VanderMeer's Southern Reach Trilogy, and that the film would be produced by Scott Rudin and Eli Bush. Alex Garland was hired to adapt and direct the film the next year. Garland revealed to Creative Screenwriting that his adaptation was necessarily based on only the first novel in the trilogy:
yes