Main characters Ada (Sharlene San Pedro), RJ (Nash Aguas), Princess (Kristel Fulgar), and Migs (CJ Navato) fight for survival as they deal with the dangers of the virus and politics among untrustworthy classmates.

[5] They were part of the original cast of the sketch comedy show Goin' Bulilit when they were children, together with Fulgar, Navato, and Celis.

[6] They were first introduced as cast of the film during its story conference held at Limbaga 77 Cafe in Quezon City on May 22.

[9] Since entering the entertainment industry starting from Star Circle Quest back in 2004, NashLene fans (derived from their names: Nash and Sharlene) have already been supporting them as a pair.

Her drama episode in Maalaala Mo Kaya (for which she received the "Best Single Performance by an Actress" nomination at the 32nd PMPC Star Awards for Television)[12] was her most recent work.

[3] The first time San Pedro learned about the project, she was offered to do the character of Princess (which became Fulgar's role later on).

[15][16] Other than scheduling conflicts with the initial actors, the production team felt Aguas and San Pedro would fit better for the roles of RJ and Ada, according to Gohetia.

For him, it was the two-minute continuous fight scene with his co-actor (Ethan Salvador) that was the most difficult part in the filming.

The released Class of 2018 teaser features an eerie version of "Itanong Mo Sa Mga Bata", originally performed by the 1970s Filipino folk-rock band Asin.

[23] With the tag "Our lesson for today is SURVIVAL", the teaser had a short synopsis: "...follows the story of a group of students who were sent to a quarantined military facility after one of their classmates got infected with a yet to be identified virus".

[24] On October 7, a two-minute trailer was released through the film producer's social media accounts with the tag "Study hard.

[25] Different from the suspense-themed teaser, the trailer focused more on action scenes in which the cast, primarily San Pedro, show off their fighting skills.

According to Alwin Ignacio of Abante, it has the "semblance of a balance and mix of commercial viability and artistic excellence".

What the film really needs is to edit its ideas, to limit what it wants to do, its stylistic flourishes, and its garish attempts at camp".

[36] Ricky Calderon of The Freeman added: "The cast did a fine job, with special mention to Sharlene who nailed her role to perfection".

[33] Both San Pedro and Fulgar were acting consistently based on their characters' emotions, said Mercado of Wow Showbiz.

[33] Nash Aguas' good acting performance was already expected; "a delight and a natural charmer", said Ignacio.

[36] According to Cruz, the disadvantage is that "the result is more like a collage of insignificant stories that only unnecessarily divert drama from the main characters".

While Nardo and Calderon describe her as the "scene stealer" of the show who does so "effortlessly", according to the latter,[36][33] Mercado said many will find her character likable.