(A 16 Unstable) Penoxycline doesn't always prevent malaria?

[Hieronymous Alloy]

http://imgur.com/a/3IQAk

See screenshot. I had started this colonist on Penoxy  . . a day or so before the malaria hit? Guess I was prescient?

Not sure if it's a bug or intended. Looks like immunity hadn't built to full, perhaps?

[Yoso]

I had several colonists get the plague but it started 92% immune. I never bothered when it just blocked malaria so I thought that might just be how it worked.

[Tynan]

He already had malaria, it was just hidden while it incubated.

Penoxy will prevent *new* infections but not existing ones.