After the House and Senate passed different bills with different amounts of funding for federal agencies’ anti-Zika virus efforts, the two chambers left for their annual Memorial Day recess without the funding questions left unresolved.

The Senate proposal offers $1.1 billion in emergency funding running through September 2017, while the House bill transfers $622 million in funding first appropriated for the 2014 Ebola outbreak, with the caveat the money would have to be used by September 2016, with more funding possible in the next federal budget. Both offer less than the $1.9 billion President Barack Obama had requested earlier this year.

Obama had asked for members of Congress to call off their recess to settle the funding dispute. Lawmakers did take one step to compromising before leaving Washington by approving the creation a conference committee so the House and Senate could negotiate a bill which could pass both chambers.

The delay in passing a funding bill worried CDC Director Tom Frieden, MD, MPH.

“We have a narrow window of opportunity to scale up effective Zika prevention measures, and that window of opportunity is closing,” Frieden during a speech at the National Press Club according to The Hill.

The CDC determined earlier in the year the Zika virus can be spread through sexual contact and mosquitoes and cause severe birth defects such as microcephaly, has been contracted by nearly 600 people in the continental U.S., all in travel-related cases.

Frieden has publicly come out in support of the $1.1 billion Senate plan, which he said would allow the CDC to received most of the $828 million in funding the agency would’ve been granted under Obama’s original request.

While there are no available treatments for Zika and a vaccine is months away from possibly entering clinical trials, both public and private health organizations are now offering blood screening for Zika after the Food and Drug Administration approved several tests for emergency use. Among the places which have recently made Zika screening available are Quest Diagnostics in Florida, the New Jersey Department of Health and the Gulf Coast Regional Blood Center in Houston, Texas.