“COVID-19. I’ll spell it: C-O-V-I-D hyphen one nine. COVID-19.”

That’s how Tedros Adhanom Ghebreyesus, head of the World Health Organization (WHO), introduced the agency’s official name for the new disease that’s paralyzing China and threatening the rest of the world. The christening yesterday, at one of WHO’s now daily outbreak press conferences in Geneva, ended 6 weeks of uncertainty about what the disease would be called—but it also created some new confusion.

COVID-19 is a name for the disease, not for the virus that causes it, which until now had a temporary moniker, 2019-nCoV, signifying it was a novel coronavirus that emerged last year. But the pathogen also got a new designation, which arrived before Tedros had even finished his press conference, by way of a preprint posted on bioRxiv by the body charged with classifying and naming viruses. The Coronavirus Study Group (CSG) of the International Committee on Taxonomy of Viruses, the paper noted, had decided to call the virus severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2.

Misunderstandings were inevitable. Journalists listening to Tedros’s press conference tweeted that the virus finally had a name, COVID-19, only to correct themselves moments later . Although nomenclature is a minor issue amid a widening public health crisis, even some virologists were taken aback by the seemingly conflicting announcements. “Ok, one day two names for the same virus,” Marion Koopmans of Erasmus Medical Center wrote on Twitter . “Sounds like some people need to meet and sort things out.”

“I agree it is a bit confusing,” says virologist Alexander Gorbalenya of Leiden University, a member of CSG and the first author on the bioRxiv manuscript about the virus. “The explanation is complex, and some people may not have enough patience.”

The discrepancy comes from WHO and CSG following completely different routes to their labels. WHO named the disease sticking to a few generally accepted principles. Disease names can’t refer to people, groups of people, or geographical locations, which can be stigmatizing; they also shouldn’t include names of animals, which can be misleading because some animal viruses jump species and become a human pathogen, as SARS-CoV-2 has done. WHO’s chosen name, COVID-19 is just short for coronavirus disease 2019. (The first known pneumonia cases from the virus occurred in Wuhan, China, in December 2019.) The name offends no one and can be recycled if other coronaviruses jump from animals to humans in the years ahead.

For the virus, CSG took a scientific approach, says its chair, virologist John Ziebuhr of Justus Liebig University Giessen. Based on its recently sequenced genome, the new virus belongs to the same species as the virus that caused the SARS epidemic of 2002–03, which is called SARS-related coronavirus. (“Species” are difficult to define in viruses, whose genomes change all the time, but Gorbalenya’s group has come up with a system to do so for coronaviruses, described in two papers in 2012, that is generally accepted, says Raoul de Groot of Utrecht University, who’s also a member of CSG.)

The virus may be novel to the rest of the world, but it isn’t really to taxonomists, Ziebuhr says, so it’s not getting its own name. Instead, the committee appended a “2” for viruses isolated from patients in Wuhan and elsewhere.

Ziebuhr says WHO has informed him that the name doesn’t sit well with China, which has resisted any comparisons between the current crisis and the traumatic 2002–03 coronavirus epidemic, which also emerged first in that country—if only because the new virus appears to have a lower mortality rate and far more often causes mild disease. ““It’s important to make clear that this name is not a reference to the disease this virus causes. There is no link between the name and the disease SARS. That’s the difficulty that WHO is facing,” Ziebuhr says. He points out that hundreds of other viruses found in bats and other animals—many by Chinese researchers—all carry the same species name as well.

A WHO spokesperson did not respond to emailed questions today, and the naming issues did not come up at today’s press conference.

Why the two names emerged almost simultaneously is a bit of a mystery. Gorbalenya says he sent the manuscript to bioRxiv on Friday. When it still hadn’t appeared online yesterday afternoon, he sent the repository an email to ask why there was a holdup. “Then it was posted within an hour,” he says. “But I didn’t know WHO would make an announcement.”

However, CSG also submitted the manuscript to a journal for publication, Ziebuhr says, which in turn sent it to WHO. (Scientific publishers have agreed to share any new information about the virus with the agency immediately.) Ziebuhr says he doesn’t know whether WHO, realizing that the name SARS-CoV-2 would be announced soon, decided to make its own announcement yesterday.

Ziebuhr says he had hoped to coordinate his group’s work with WHO, as happened with the Middle East respiratory syndrome–related coronavirus, or MERS-CoV, which emerged in Saudi Arabia in 2012. Then, WHO was on board with the name , as was the Saudi government and other stakeholders; it was effectively a joint announcement. (The partners all agreed to make an exception to the no-location rule, deeming the Middle East big enough that no specific group would be stigmatized.)

That sort of coordination simply wasn’t possible now, Ziebuhr says. “WHO is so overwhelmed with what’s going on there, they didn’t have the time,” he says. But the name “needed to get out,” Ziebuhr says. “Scientists want to have clear guidance.”

Koopmans, who’s a member of a WHO advisory committee on the disease, says, “Ideally, these releases would have been coordinated.” What happened yesterday was “a bit chaotic” says Koopmans, who attended a meeting in Geneva the past 2 days to set research priorities for the new virus. But she doesn’t see it as a major issue.