The cover for Kodansha’s Morning magazine on Amazon announces Cells at Work! Code Black will receive an anime adaptation and set for January 2021. The spinoff is based on the popular manga series Cells at Work by Akane Shimizu. It dives into an unhealthy body with a darker tone compared to the main series. Additional details have yet to be announced for the anime adaptation.
Cells at Work!! (Season 2) was recently announced for January 2021. The first season originally premiered July 2018 and is animated by David Productions.

Kodansha Comic describes the spin-off series as:
In this new spinoff of the hit manga Cells at Work!, a newbie Red Blood Cell is one of 37 trillion working to keep this body running. But something’s wrong! Stress hormones keep yelling at him to go faster. The blood vessels are crusted over with cholesterol. Ulcers, fatty liver, trouble (ahem) downstairs … It’s hard for a cell to keep working when every day is a CODE BLACK!
Aniplex of America describes Cells at Work as:
This is a story about you. A tale about the inside of your body… According to a new study, the human body consists of approximately 37 trillion cells. These cells are hard at work every day within a world that is your body. From the oxygen carrying Red Blood Cells to the bacteria fighting White Blood Cells, Get to know the unsung heroes and the drama that unfolds inside of you!
Source: ANN