First published May 17, 2016; Last updated June 23, 2016

The Obama administration says the Zika virus is the nation’s next big public health threat. But there is continuing disagreement on how much money it will take to counter it and where that money will come from.

And delays in reconciling those visions could be forestalling needed intervention to head off the mosquito-borne virus, whose rapid spread globally has for months fueled concerns.

After initially pushing for $622 million, the House of Representatives voted early June 23 on a $1.1 billion package. That package came out of a conference committee between the two bodies of Congress – negotiations from which Democrats say they were excluded. The House is now adjourned for its July 4 recess.

Meanwhile, the Senate has been pushing for $1.1 billion, which it voted to allocate in May.

But major differences exist between the bodies’ visions. In the House package, $750 million would be offset by funding cuts to other programs. The plan would also deny Planned Parenthood, a major women’s health provider, access to the money.

President Barack Obama – who has been calling for months for $1.9 billion – hasn’t formally threatened to veto the new bill. But his administration, which had indicated openness to the original Senate bill, has sharply criticized the new package. Senate Democrats have also suggested it will face an uphill fight.

But what does this mean? Here’s a primer on the virus, the public health risks it poses and the House and Senate’s proposed response.

Zika can have major consequences for children if their mothers are infected while pregnant. There’s been a surge in cases, and now public health experts think it’s only a matter of time before the virus reaches the United States.

Zika has been spreading through Latin American and African countries since last year. In February, the World Health Organization deemed it a public health crisis. It has caused one death so far in Puerto Rico, where more than 1,000 cases have been diagnosed and mosquitos have also actively transmitted the virus. There’s no known cure or vaccine.

Elsewhere in the United States, more than 700 cases have been diagnosed, with about 150 in Florida. Those cases have all been contracted by people traveling outside the country, but with summer approaching experts think Zika could soon spread here, too. This expectation is why Florida lawmakers such as Republican Sen. Marco Rubio have been calling for quick funding.

For most people, getting Zika is like an unpleasant flu and rash. But for expectant mothers, the disease has been linked to birth defects in their children. It is believed to cause microcephaly, which stunts brain and head development, and has been linked to pregnancy loss. The World Health Organization in April said it also appears to increase the risk of Guillain-Barre, an autoimmune disorder that can temporarily paralyze patients, for people who contract it.

Both proposals would fund prevention efforts in states and territories where the risk of Zika is greatest. It would also give money to aid vaccine development and support efforts to tamp down the virus abroad. The plans mainly vary in terms of scale.

The Senate proposal, classified as an emergency funding request, includes two pots of money: about $850 million for the U.S. Department of Health and Human Services to fight Zika domestically, and $250 million for efforts abroad. HHS would have 30 days to inform Congress about a precise spending plan for these funds. The State Department would get 45 days.

The Senate does provide some guidance. In the HHS bucket, close to $360 million is for the CDC, which can disperse money in areas threatened by Zika. Another $200 million is for the NIH to support vaccine research.

HHS also has a public health emergency fund, which would get $150 million, split between vaccine development and money for states. Then, close to $50 million would be directed to Puerto Rico to shore up community health centers, pay for health workers and support things like maternal and child health care, which are relevant because of the health consequences for pregnant women and newborns. Another $80 million would support other public health efforts.

The State Department funding would support similar activities in affected countries such as Brazil, Cuba and Trinidad.

The new House package is similar from a numbers standpoint: It gives $476 million to the CDC and $230 million to the NIH. Another $85 million would go to the Biomedical Advanced Research and Development Authority, another HHS subsidiary that emphasizes emergency vaccines. Another $140 million would be split over funding community health centers, the National Health Service Corps and a special fund that would be deployed in areas where Zika is being transmitted. The State Department would get $175 million.

The difference is that in this proposal, other areas would face funding cuts to the tune of a $750 million total: Those funds would be pulled from what’s allocated toward implementation of the 2010 health reform, administration funds for HHS and combating Ebola. Planned Parenthood would also not be eligible for any money in the package – an exclusion Democrats criticize, given the organization’s prominence as a women’s health services provider, as well as Zika’s disproportionate consequences for pregnant women and ability to be sexually transmitted.

Experts say the virus poses a unique threat and requires a multipronged approach.

Zika requires an attack from many angles, said James Blumenstock, chief program officer for health security for the Association of State and Territorial Health Officials.

The environmental aspect — spraying areas to eliminate the mosquitos that carry it and prevent further breeding — is key.

To that end, a good chunk of money could go toward supporting such local mosquito control programs. States haven’t prioritized these efforts “for decades,” said Jeffrey Klausner, a professor of medicine and public health at the University of California, Los Angeles. And because of the “patchwork” nature of many local programs, the expectation is that most of the funding meant to prevent transmission will go to states where risk is great — parts of Texas, for instance, said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine. Other gulf states would also likely make this list.

Meanwhile, the NIH has five promising avenues for Zika vaccine research. The $200 million would likely be enough to get at least one of them to the earliest phase of clinical trials by this September, said Anthony Fauci, head of the National Institute of Allergies and Infectious Diseases. But that still isn’t in time to address any outbreak this summer.

If the Senate’s proposal were to be adopted, it would be a major upgrade from the federal government’s current anti-Zika investment.

In April, HHS gave $5 million to Puerto Rico-based health centers. The money is for education, contraception — Zika is sexually transmitted, too — and expanding the centers’ staffs. The CDC, in its existing budget, provides up to $85 million for states and cities to use for things like better mosquito control and emergency preparedness.

Then there’s the White House’s $590 million. It’s intended for mosquito control, better diagnostic tests and vaccine development as well as additional resources for Puerto Rico.

On the state level, advocates say prevention efforts have been constrained by lack of funds, and many officials are waiting on Congress for money.

It’s still unclear whether this funding will go through.

The House’s new package was meant to be a compromise, but Democratic reaction suggests it isn’t quite coming off that way. If the bill doesn’t pass the Senate — or if Obama vetoes it — lawmakers will have to go back to the drawing board.

Anything helps, Blumenstock said, but states need meaningful resources to make a real impact.

And the clock is ticking, especially with summer now in full swing.

Both “political will” and understanding of the public health threat may still be missing, Hotez said. “We may have to wait for Zika cases to appear on the Gulf Coast before serious funds are mobilized.”