They aren’t zombies, but they are infected. I remember a scene where the doctor clarified that they are similar to zombies but not zombies. Maybe it was around the scene where the officer was stuck in the truck.
Zombies are dead people. The subjects of this drama aren’t dead, they’re alive and infected. That’s one thing to be cleared.
Thanks! Your clarification plays a role in my decision to watch, I am still deciding. 
ALL I can say is you will MISS out on a TERRIFIC drama from beginning to end - if you don’t watch! I’m not usually a ZOOMBIE (my name) watcher or a thriller watcher but PHS - SIKKIE drew me in!!! He is so bad!@# and so is his “wife” - I am a huge Park Hyung Sik fan and he chose one of the BEST scripts - Happiness is in the #1 slots and is getting quite the accolades - I hope you watch!!!
The characters in the people are well worth hating and you even get a couple of mystery characters!
This has helped me move away from Rom-Com and also watch SEARCH with Jang Dong Yoon from Nokdu - and I’m on the edge of my seat with both.
12 Eps well worth it I say!!! Take the Leap - But LEAVE the LIGHTS on!!!
(It does truly work with the signs of the times with covid going on - it also shows how humanity reacts during a crisis - you do see the kind and the desperate and the scummy side of people - which is REAL)
This was a reason not to watch, but like shraddhasingh clarified,
I look at them like vampire zoombies kind of!!! But yes they are alive and infected but the disease looks like zoombie vampires! 
SEARCH is more
werewolf zoomies!!! LOL
Even though the virus that causes these zombie-like symptoms is the major driving factor of the story, the actual ‘zombies’ (maybe it’s better to refer to them as patients) are not running rampant through the scenes all the time. Sometimes you barely even catch a glimpse of one in any given episode. The story is really about how the stress and uncertainty of the outbreak and the subsequent lockdown affect the people living in the apartment complex. It’s very much a character-driven story, with a sprinkling of action. Ultimately, since it is a virus, the goal is to hopefully find a cure.
I just started watching and didn’t read the ‘‘about’’ and I thought it would have some romance since they ‘‘got married’’ (I know is fake), but although there is an extra room in the apartment, they are sleeping in the same bedroom. That hunk…he would be attacked so fast by me, and not bc I had the ‘‘zombie virus’’ bc I took the dreaded pill…
I find that actor so handsome, so sweet and sigh so good enough to eat veryyyyyy… slowly to enjoy every ounce of him. I hope there is something romantic between them bc if not, to me, that will be a waste of MY time. Since the ‘‘zombie state’’ story has become so fake, I see no point in watching if there’s no romance in the horizon…
So naughty. And I think a lot of us agree that we’d personally take more advantage of the ‘fake’ marriage situation. He’s one of my favorite actors. I could (and sometimes do) watch him all day long.
You are way ahead of me. What episode is that from? Don’t tell me that’s the old man…
I hope is not his friend detective either. Geez, nooooooo 
PS The HUNK I need a list of his drama to refresh my mind (I think I saw him once before but don’t remember which drama).
NOTE
I believe the writer took a bit from what happened here (don’t remember how long)
I can’t find anything on the one that happened here in Manhattan area. …
But there is something more horrible happening with this synthetics drugs that look like the ones from the drama HAPPINESS
Russia - Arrest Of Drug Smugglers At Airport
The effects of this drugs
Krokodil - Russia’s Deadly ‘Flesh Eating’ Drug
](https://www.youtube.com/watch?v=-xF1ejbShZ8)
PS. My Theory is: they made this killer drugs for drug addicts (in some countries) to end the out of control drug problem they were facing, and it seems to work bc at one point this drug trafficking was getting so out of control it was really scary. Even seniors/elderly ppl. were selling and using. Such a disgrace to have to see…
I remember hearing about the bath salts incident. So freaky.
That epic move though!!!
I recall some of those incidents in New York and Miami. It was terrifying to see.
Drugs certainly explain the intermittence between zombie and normal. Makes sense to call it infected now as @shraddhasingh stated. However, this doesn’t explain the virulency, or the fact that infected people remain infected despite no longer taking the drug.
I guess we’ll have to chock that up to drama logic.
Um…If you’re watching for romance, I think you’ll be sorely disappointed. It’s a zombie-like apocalypse that’s spreading throughout the globe (as stated in the first few episodes by the Lt. Colonel), so the characters have bigger fish to fry.
On and the first part about tenants not coming together, no plan for protection, and people just genrally acting stupid, that’s very real. WTF do you do in a zombie-like apocalypse? Who knows? 
Yes, we have to ‘‘chock it up’’ as an Asian drama’s logic thingy because if we don’t, we might never watch certain dramas like HAPPINESS here, that is not making much sense.
Like the part where the Chairman is eating (the guy in charge wife’s neck). She’s calling out ‘‘honey, please honey help,’’ and the idiot is not moving an inch, just staring at her. Now, I found out she was/is pregnant with his child, and somehow he has kept her alive (another not making much sense part) I can pull my hair right now lmao. To add insult to injury, he didn’t killed the Chairman that infected his pregnant wife, like he has killed others from left to right, WHY??? Knowing drama logic; the ending might suck big time like they have done so many times in other dramas (Did you see MY NAME?) I had high blood pressure for days with that one.
I’m sorry but I won’t stay alive to witness that, you can bet on that for sure. No way in HELL, I will endure the fear ZOMBIES after me. It gives me an irrational fear, and I can’t explain why but is one of those things I can’t stomach too well, either. I’m not a COWARD at all, but zombies can make me easilyyyy wear diapers or out it goes (ugh) .lmao
High Society
https://data.whicdn.com/images/304151748/original.gif
Strong Woman Do Bong Soon
https://c.tenor.com/DarehOlMUw0AAAAC/park-hyung-sik-hyung-sik.gif
Suits
https://c.tenor.com/On948yu4QgEAAAAC/park-hyung-sik-hyungsik.gif
Hwarang
Happiness
@angelight313_168
So since I’m the resident Hottie watcher - Here are a few of the dramas that our HUNK has been in!
He also is a member of the kpop group ZE:A and sings in musicals!!!
Here he is in Elizabeth!
Park Hyung Sik - SIKKIE
That made my DAY
