Young and Lanham first started writing together for The Vaccines' Combat Sports album 2018, and soon travelled to Paris to begin writing for their new project. In March 2019, the duo headed to Oakland to record their debut Halloweens material with Luke Temple (Here We Go Magic, Adrianne Lenker).
Justin Young says of their Halloweens project, "the record came from a period of writing without consequence or compromise where the only requisite was ‘do we love this?’. Being able to write and record a record that nobody expects is an incredibly empowering and exciting process, free from the fog of ambition or fear."
The Vaccines' last single was Shaun the Sheep Movie: Farmageddon track "LAZY" featuring Kylie Minogue.