The death toll from an outbreak of the Ebola virus in the Congo has hit 26 with fears it could spread to neighboring countries.

The country’s government has agreed to increase emergency-response funding to over $4 million, AP reported. Ebola victims are being provided with free health care. Some 4,000 vaccines were ordered Saturday – but officials may struggle to keep them cold enough to remain effective.

An emergency committee convened by the World Health Organization met but decided the situation didn’t yet merit being classed as a public health emergency and stopped short of calling for travel restrictions. However, WHO warned that nine neighboring countries are at a high risk of being affected.

The U.S. government is preparing its most direct response yet to the outbreak that appears to have begun in April, readying staffers from the Centers for Disease Control and Prevention to deploy to multiple communities in Congo.

Ministry of Health officials first identified cases of viral hemorrhagic fever when it reached the town of Bikoro earlier this month. On Thursday, officials said a new case had been identified in Mbandaka, a city of 1.2 million. The new case in Mbandaka has raised the alarm among health officials because it is the first time the virus has ever landed in a city that sits directly on the Congo River.

In all eight of the previous known Ebola outbreaks in Congo, the virus has been contained within remote jungle villages or relatively small towns, where isolated populations are less likely to spread the disease.

“The Congo River connects three national capitals and multiple other large cities,” said Jeremy Konyndyk, who led the U.S. Agency for International Development’s Office of Foreign Disaster Assistance during the 2014-2015 outbreak. “The fact that there are now several cases in an urban center of more than a million people underscores the potential for this outbreak to get out of control.”

Aiding the response is a new vaccine, finalized in the last days of the West Africa outbreak. About 4,000 doses of the vaccine are headed to the epicenter of the new outbreak, where they will be used in two ways: First, health-care workers, those most vulnerable to exposure, will be vaccinated. Then, those who have come into contact with anyone infected, and the contact’s contacts, will be vaccinated, a practice known as ring vaccination.

Health workers in the Congo will begin a vaccination campaign on Monday aimed at containing an outbreak of the deadly Ebola virus, a spokeswoman for the health ministry said.

A previous outbreak of Ebola in west Africa in 2014 and 2015 killed more than 11,000 people. An unrelated outbreak in the Congo in 2014 killed 41 people. There have previously been eight outbreaks of the disease in Congo since 1976, which is when it was first identified.

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