I’m currently playing the first intermediate scenario (Show me the money) so it’s my first time encountering level 4 diseases.
For the latest event i don’t remember the exact wording but it was effecting Tuberculosis. What i remember was false fears surrounding vaccines. So my simple interpretation is: Fear of vaccine -> less people vaccinate -> leading to more infections. Which was good (for me) as i’m only few months away from researching the machine that allow me to upgrade my bronchitis-drug to Tuberculosis.
The event is running for some time now and i’m checking the cure-tab to see this:
I guess what is happening is that the event is reaching its end and the previous increase gets removed again. Still i find it strange - i thought the after-event decrease starts when i get the “event finished”-message (which i haven’t got so far)