Update in version 3:
The contagion-beast which snuck into the colony purifiers has been found and removed: Cities no longer generate -50 health each. Sorry for the lapse.

Update in version 2:
It gets worse:
- In Vostok or Gemini difficulties, negative yields that were -1% are now -2%
- In Soyuz or Apollo difficulties, negative yields per unhealth increase to -3%
But there is still hope:
- Military-enforced quarantines help reduce disease outbreaks: The tier-1 Might Policy "Public Security" now provies 0.33 health per military unit, up from 0.25.
- Integrating native flora into our colonists' diets has provided some surprising resistances: Plantations now provide +1 Health
- Negative Energy and Production yields have been swapped - It's a litle easier to dig out from unhealth penalties through construction than it used to be.