I looked around and I don't know if I am looking in the wrong place but all I can find is that you were only able to become a zombie during the 2009 Pandemic? I feel that's wrong and that it's an annual thing? Or is there another way to become a zombie?

Zombies used to be an annual event until 2013 (i think) and said there would be no more permanent zombies. In 2014 you could become a temporary zombie using one of these vials. which when it has progressed to the final stage will give you access to the w014 zombie den stuff and the alchemist.

So if I use one of those vials I could get a zombie skin?

A temporary one, I'm not sure how long it stays active, but it does revert you back to human

if you mean like unlock a skin in the wardrobe, it doesnt. I tried with the vials a few weeks ago (unless things have changed).

Yup, yearly zombie strains were discontinued in 2012 (2012 being the last year it happened). Staff is considering bringing zombie skins back, but at the moment the only way to access zombie areas is by taking one of the temporary vials mentioned :x

Yeah, if you wanted to unlock a 2009 zombie skin then the only current way to do so is if have had the infection since 2009. Same with all the following years. It's still unknown if they will make the 2009-2012 zombie skins available in some other way. The 2014 vials do not unlock a skin and only temporarily give you access to the 2014 zombie den items.

Thank you for all the information.