Development of a vaccine to combat the Zika virus is on track for at least the next three or four months, despite the bitter congressional standoff over funding a response.

But the scientist in charge of the effort said Wednesday the money is likely to dry up in December. Funding for vaccine research at the National Institutes of Health was part of a much broader $1.9 billion request from the Obama administration that’s been the subject of much wrangling this year on Capitol Hill.

“We asked for $277 million, and if you do the math and you look at all the money that was reshuffled in different places, when you pay it back, we still need $196 million to go through 2017 and into 2018,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in an interview.

Where Does the U.S. Stand With Zika Funding?

Fauci’s team has relied on reprogrammed dollars shuffled between government accounts, including last week’s reallocation of some $34 million within the NIH by Health and Human Services Secretary Sylvia Mathews Burwell. Fauci said Burwell wanted to avoid the transfers because they will eat into research of conditions such as heart disease and cancer.

“We have to spend that money by the end of September,” Fauci said. “We are going to be funding things that we’re going to be doing starting in January and February. So, when you get to October, November, December, we’re not going to be spending any additional money because we already put it into the contracts and the things to start.”

[HHS to Transfer Funds to Help Fight Zika Virus]

He predicted the possibility of a funding drop-off unless Congress agrees on stopgap measures to keep federal agencies running.

“If we get a continuing resolution, we can still do what we’re doing until like maybe December, and then, all of a sudden, we start to get into real trouble,” Fauci said. “So, when we get to calendar year 2017, and we essentially run out of the money that we had forward funded into the areas to keep the vaccine going, we’re going to be back in trouble again.”

A stopgap appropriations measure that runs past Election Day would give Burwell some new spending to move around on October 1.

“The thought of that gives me a chill. It does,” Fauci said when asked about further shifts. “I can tell you that would have so many negative effects — not only negative effects on the actual conduct of research in cancer and heart disease and diabetes. It would be very demoralizing to the biomedical research community to see that.”

Fauci told Roll Call that a large-scale Zika outbreak such as those seen in Brazil and Puerto Rico is “extremely unlikely” in the continental United States, though not impossible. He warned against complacency, given that there’s an expectation of additional localized outbreaks, particularly along the Gulf Coast.

[Republicans Shocked White House Won’t Bite on Zika Funding]

Fauci said he understood public confusion about the severity of the threat. Zika presents “relatively mild” symptoms, except in pregnant women, whose babies are vulnerable to microcephaly, a severe birth defect in which the newborn can have an abnormally small head.

“That dichotomy of a mild illness on the one hand with potentially devastating consequences on another creates a bit of confusion about how serious is that and what should we be doing about it,” Fauci said. “When we start seeing the devastation of even a handful or so of babies born with microcephaly or who have congenital abnormalities, that is going to have as profound an influence on ‘Did we do the right thing?’ as a less severe infection that has broad dissemination, like influenza.”

Fauci seemed aware it could take only a small number of cases to generate even greater media and public attention for Zika, in contrast with a condition like the flu.

“People don’t get excited about influenza except when there’s the threat of a pandemic,” he said.

The lengthy debate over funding to combat Zika devolved into a standoff where Senate Democrats blocked a GOP proposal that would deny family planning assistance from going to groups like Planned Parenthood. In places like Florida, the fight is spilling over onto the campaign trail.

[Zika Spending Stalemate in Congress Spills Over Into Campaigns]

But Fauci said being on the pivot point of the summer’s biggest funding fight doesn’t make him feel like a politician.

“There’s a lot of back-and-forth between Democrats and Republicans about how much should be funded, what the mechanism of the funding [should be]. I don’t get involved in that and have never gotten involved in that because I have to maintain, as I do, my credibility as a scientist,” he said. “The decision about how that’s going to come about, you leave it up to things that are well beyond any control I can have. I can only give the scientific information as I know it.”

Contact Lesniewski at NielsLesniewski@cqrollcall.com and follow him on Twitter @nielslesniewski.