The End of the World (2013)

Both drama set in large-scale catastrophe, showing how the characters face ethical dilemmas in life-or-death situation.

I honestly don't know why this recommendation hasn't been done after all this time these two dramas have been realeased. Both stories involve a deadly virus that has a 100% fatality rate. The End Of The World is focused more on the medical/science side and The Virus falls more in the crime (and of course medical) genre. Watch both and pick your favorite.

both are jtbc dramas, means are of a certain quality. one is about a microorganism ending the world, one is about a big earthquake hitting seoul so they have a similar genre and both are good.

Both feature zombies, obviously, but they also show that, apart from a few heroic figures, bureaucracy and figures of authority are more interested in saving their ass*s and holding onto their power, instead of really tackling the "zombie problem" at hand.