The World Health Organization (WHO) will hold an emergency meeting on the coronavirus on Thursday as officials consider whether to declare a public health emergency.

Dr. Tedros Adhanom Ghebreyesus, the director-general of WHO, announced the meeting on Wednesday, saying he decided to reconvene the International Health Regulations Emergency Committee to discuss the coronavirus outbreak and advise him on declaring a health emergency.

In a series of tweets, Tedros wrote that only 68 of more than 6,000 new cases of coronavirus have been confirmed outside of China, but there has been person-to-person transmission in three countries other than China, signaling a “potential for further global spread.”

“This potential for further spread is why I called the EC,” Tedros wrote.

WHO decided against declaring a global public health emergency last week, noting that the coronavirus was indeed an emergency in China, but did not rise to the level of a public health emergency of international concern. That special designation is reserved for serious crises, and officials postponed the decision to gather more data.

At that time, there had been roughly 600 cases reported in China and just 17 deaths. But in the span of a week, Chinese officials report the coronavirus has infected more than 6,000 people with 132 deaths and thousands more suspected cases. The virus has spread to at least 16 countries globally and four states in the U.S., which has five confirmed cases.

Tedros said the vast majority of cases have been reported in China, and most cases reported outside the country involve people who visited China or have been in contact with people who have been in the country. But Tedros said there are some signs of person-to-person transmission outside China.

The director general said most infected patients experience milder symptoms, but about 1 in 5 people have severe illness, including pneumonia and respiratory failure.