(NEXSTAR) – A few months ago, the World Health Organization decided it needed a better system. Coronavirus variants with meaningful differences were springing up around the world and we didn’t know what to call them.

Names like B.1.1.7 didn’t exactly roll off the tongue and calling a variant by the place it was discovered was having some hateful unintended consequences. So the WHO got a group of experts together and they went for something simple and neutral: the Greek alphabet.

Since the system was announced on May 31, the names have seeped into everyday vocabulary. (We’re all too familiar with the delta variant at this point.) It seems to be working well as a tool of communication, but there’s only one problem: What comes next?

There are only 24 letters in the Greek alphabet and we’ve already used half of them to identify what the WHO calls “variants of concern” and “variants of interest.”

What will happen after the omega variant is identified? (The last letter of the Greek alphabet is omega, by the way.) Maria Van Kerkhove, coronavirus lead at the WHO, told STAT News that once they’ve run out of Greek letters, the WHO will announce a new series of names to pick from.

What exactly that series will be is still a mystery to the general public, but the WHO has already ruled out a few categories, reports Reuters. Bacteriologist Mark Pallen, who was part of the deliberations on naming conventions, told the news outlet the group was considering the names of Greeks gods and goddesses, plants, fruits and even lost religions before they settled on the alphabet. However, many of them were already brand or company names, Pallen said, which posed a potential issue. (Just ask Delta Airlines.)

Another category that’s been ruled out is place names. Before the Greek system, some were distinguishing between variants by their suspected point of origin (i.e. the Wuhan variant, the South African variant, etc.). The WHO suspects its because the variants’ scientific names were too hard to say or keep track of.

“While they have their advantages, these scientific names can be difficult to say and recall, and are prone to misreporting. As a result, people often resort to calling variants by the places where they are detected, which is stigmatizing and discriminatory,” the WHO said.

You can see all the variants of concern and variants of interest on the WHO’s website.