In 2009, Jochen Koenigsmann showed that $\mathbb{Z}$ is universally definable in the field $\mathbb{Q}$. My question is, are there any other number fields in which $\mathbb{Z}$ is universally definable?

Or failing that, what is the lowest complexity definition of $\mathbb{Z}$ known for a number field other than $\mathbb{Q}$?