Increasingly concerned about the spread of the Zika virus, the Obama administration said Wednesday it is transferring almost $600 million from existing disease prevention funds to fight the mosquito-borne virus.

The White House said the emergency transfer was necessary since Congress has continued to deny the administration’s $1.9 billion request for funds to stop Zika from gaining a foothold in the U.S. The transfer, including $510 million earmarked for ongoing Ebola efforts, will be used to help develop a Zika vaccine, improved diagnostic tests, and to help states prepare for the possible arrival of the mosquito-borne disease as temperatures warm. The disease is strongly linked to devastating birth defects.

The White House made the initial emergency request for Zika money in February, but Congress said the administration should use funds left over from the fight against Ebola. An additional $79 million from other prevention programs is also being redirected toward Zika, White House officials said. Even with the transfer, the administration reiterated its demand for the $1.9 billion.

“The situation continues to grow more critical,” said Shaun Donovan, Director of the Office of Management and Budget. “We must scale up right now.”

Georgia saw its first case of Zika in February and in just over two months the number of travel-related cases in the state has risen to 11. None of those cases involved pregnant women, but the state public health department has tested 78 pregnant women who thought they had been exposed to the virus through travel, said Nancy Nydam, spokesperson for the department. Two of those 78 thought they had been exposed to Zika by a sexual partner who had recently traveled to an area currently experiencing a Zika outbreak. The disease can be sexually transmitted as well.

Since the first case of Zika The number of Zika cases in the U.S. and its territories stands at 672, including 64 pregnant women. The disease is strongly linked to microcephaly, a birth defect that causes severe, long-term health care issues for babies born with it.