Although the WHO’s emergency committee on June 25 “advised that the outbreak, at this stage, should be determined to not constitute a public health emergency of international concern, the rapid evolution and emergency nature of the event means that the committee will revisit its position shortly,” Dr. Hans Henri P. Kluge, WHO regional director for Europe, said in a Friday statement.

WHO Director-General Dr. Tedros Adhanom Ghebreyesus and the committee had agreed that the outbreak should be “closely monitored” and the decision not to declare an emergency be “reviewed after a few weeks.”

Factors that could trigger a reassessment of the situation could include evidence of increased growth rate in cases, an increase in cases in vulnerable groups like children, an increase in hospitalization or death rates, and significant mutation affecting how the disease presents, the committee said.

As of Friday, global cases had nearly doubled since the decision not to declare an emergency was announced six days prior. Cases sat at 5,800, according to the U.S. Centers for Disease Control and Prevention, with one death reported.

“Let me be clear: There is simply no room for complacency—especially right here in the European region, with its fast-moving outbreak that with every hour, day, and week is extending its reach into previously unaffected areas,” Kluge wrote.

Europe is home to nearly 90% of new lab-confirmed cases globally since mid-May. Since mid-June, cases there have tripled, he said.

While most cases have been identified in 21- to 40-year-old males, many of whom have sex with other men, “small numbers of cases have also now been reported among household members, heterosexual contacts, and nonsexual contacts, as well as among children,” according to Kluge.

Nearly 10% of patients have been hospitalized, but there have been no deaths in the region, he added.

He did not say when the committee would meet again. On Wednesday Tedros told reporters that the committee would reconvene “as soon as possible,” citing the virus’s move into the pediatric population, among other factors.

WHO officials at a Wednesday press availability dodged a question as to exactly when the committee would meet again. An email from Fortune to the WHO last week asking when the committee would meet again went unanswered.

In his Friday statement Kluge called for governments to “scale up efforts in the coming weeks and months to prevent monkeypox from establishing itself across a growing geographical area.”

“Urgent and coordinated action is imperative if we are to turn a corner in the race to reverse the ongoing spread of this disease,” he wrote.

The White House on Tuesday announced the first phase of its national monkeypox vaccine strategy, saying it would release tens of thousands of doses “immediately” from the Strategic National Stockpile—with millions more on their way in the coming weeks and months.

Individuals at high risk of contracting monkeypox and areas with the highest number of cases will be prioritized, officials said.

As the virus continues to move beyond Africa, where it’s endemic, via an atypical pattern, scientists are rushing to figure out just how it’s spreading.

Monkeypox is usually found in rural African areas where people have close contact with infected rats and squirrels. Recent cases, however, have occurred in countries where the virus has not previously been seen, and in individuals without a travel history, indicating that it likely has been circulating unnoticed for some time.

When the virus is transmitted human to human, it’s typically through close contact, which may include sex and could include contact with personal items like sheets and clothing. While not considered a sexually transmitted infection, public health officials say many recent cases have been found among men who have sex with men, and note that it’s difficult to tease out sexual transmission from close-contact transmission. Airborne transmission is known to be possible but has yet to be confirmed.

With smallpox declared eradicated by the WHO in 1980 and the vaccine, which works on monkeypox, no longer widely administered, the population has a low level of immunity against poxviruses, WHO officials have said. That means transmission into the wider population could occur.

Symptoms are similar to but milder than those of smallpox, according to the CDC. Initial symptoms usually include fever, headache, muscle aches, and exhaustion. Within one to three days, patients develop a rash, usually starting on the face and then spreading to other parts of the body. Lesions progress through various stages before scabbing. The illness usually lasts two to four weeks. The typical incubation period is seven to 14 days but can range from five to 21 days.

But symptoms in new cases appear to differ from those of classic cases—at least in some instances—with recent reports of lesions more subtle than usual and some cases involving just one lesion, health officials have said.

WHO emergency committees currently exist only for COVID-19 and polio. Seven additional past emergency committees have previously been convened for diseases including Ebola, H1N1, and MERS.