(CNN) -- A new SARS-like virus recently found in humans is "a threat to the entire world," according to the director-general of the United Nations' World Health Organization.
The so-called novel coronavirus "is not a problem that any single affected country can keep to itself or manage all by itself," Margaret Chan said Monday in her closing remarks at the 66th World Assembly in Geneva, Switzerland.
The world needs to pull together its resources to properly tackle the virus which, Chan said, is her "greatest concern" at present.
"We understand too little about this virus when viewed against the magnitude of its potential threat," she said, and more information is needed "quickly" and "urgently."
"We do not know where the virus hides in nature. We do not know how people are getting infected. Until we answer these questions, we are empty-handed when it comes to prevention. These are alarm bells. And we must respond," she said.
Novel coronavirus is part of a family called coronaviruses, which cause illnesses ranging from the common cold to SARS, or Severe Acute Respiratory Syndrome, as well as a variety of animal diseases. However, the new virus is not SARS.
The virus had infected 44 people worldwide as of last week, most of them in the Middle East, according to the World Health Organization's most recent update Thursday. Half of them have died.
Also in its Thursday update, the WHO appeared to have given the novel coronavirus a name: Middle East respiratory symptom coronavirus, or MERS-CoV.
A 23rd death was reported Tuesday, when a French hospital and the French government reported a man diagnosed with the coronavirus had died of organ failure.
The patient, the first of two people to be diagnosed with novel coronavirus, died at University Hospital of Lille, where he had been treated since May 9.
The man contracted the virus while visiting the Arabian Peninsula, said Marisol Touraine, France's minister of social affairs and health, in a statement.
The second patient, also male, was in stable but very serious condition, the hospital said. One of the patients shared a room with the other and contracted the virus.
Joint WHO missions with Saudi Arabia and Tunisia will take place as soon as possible, with the goal of gathering the facts needed to conduct a risk assessment, Chan said Monday.
Earlier this month, the WHO said two health care workers in Saudi Arabia became ill while treating patients.
Novel coronavirus acts like a cold virus and attacks the respiratory system, the Centers for Disease Control and Prevention has said. But symptoms, which include fever and a cough, are severe and can lead to pneumonia and kidney failure. Gastrointestinal symptoms such as diarrhea have also been seen, according to the WHO.
It's not yet known how humans contract the virus, experts have said. Most of the cases so far have been seen in older men with other medical conditions; precise numbers are hard to come by, as officials don't know how many people might contract a mild form.
Cases have been identified in eight countries including France and Saudi Arabia, according to the WHO. Other European countries include Germany and the United Kingdom.
No cases have been reported in the United States, but infectious disease experts have said it would not be surprising.
Journalist Saskya Vandoorne contributed to this report.