Acting is decent. Idea and process behind the plot of an infectious disease outbreak, despite the increasing fad of this genre more recently, is still developed quite well.
The development of characters, however, is poor. The change in personality of some characters is way too drastic, it makes no sense at times. It is especially infuriating when one character changes completely and makes a 180 degree change in their behaviours/attitude, so exaggerated to the extent that it makes no sense outside of being in a Korean drama. It is hard to enjoy the drama for what it is when there are so many behavioural and emotional inconsistencies with some of the characters. This is not a reflection of the acting itself as I see it, but because of the character/role they are asked to perform/act and how that shift in their character makes no sense. It is the decision of how these characters should behave/act throughout the show that not only makes no sense but is also annoying for its inconsistencies.
Other than this, I think the number of characters that are purposefully made to be annoying characters are far too high in number. Why are there so many annoying characters!? Having a couple in a drama is fine but I find myself counting which characters I DON'T find annoying in this show... I would give this show a truthful rating of 6.5/10 but I put down 1/5 because the rating on this show is already way too high.
Watch with patience, and maybe if you don't care or think about the characters too much (and their very sudden shifts in behaviour/attitudes), it could be a decent watch.