A flu epidemic that's filling hospitals across the U.S. False alarms about incoming missiles in Hawaii and Japan amid escalating threats of nuclear attacks. The lingering impact and prolonged recovery from Hurricane Maria in Puerto Rico.

They all set the stage Wednesday as the Senate Health, Education, Labor and Pensions (HELP) Committee began the process of reauthorizing the 2006 Pandemic and All-Hazards Preparedness Act (PAHPA), which provides funding through this fiscal year for the research, development and national stockpile purchase of medical countermeasures (MCMs).

"The threats we face continue to evolve," Sen. Richard Burr (R-N.C.) said in opening the first hearing on the reauthorization. To prepare for the threats of the future, be they natural or man-made, it's critical to foster and advance innovation in drugs, devices and diagnostics, he added.

Burr urged committee members to resist the temptation to add other measures that could hinder reauthorization of what has been a bipartisan effort. The hurdle is not innovation in medicine; it's government, Burr said.

In its first iteration, PAHPA led to the FDA approval of 34 MCMs that were supported by the Biomedical Advanced Research and Development Authority (BARDA); 12 drugs were approved under the Animal Rule. Speaking to the accomplishments under PAHPA, FDA Commissioner Scott Gottlieb said the FDA is doing a much better job of "leaning in" to develop and approve MCMs.

But getting MCMs from concept to approval is just one part of preparedness. Gottlieb reminded the lawmakers that the MCM marketplace isn't the typical drug and device market, so there are no market incentives to encourage and sustain development of products that everyone hopes will never be used.

Companies that develop products only for the national stockpile and have little demand for new inventory could fail. Then, if a threat becomes reality, the MCMs they developed would no longer be available once the stockpile supply is exhausted or expired.

There have to be incentives to help sponsors through this "second valley of death," as Robert Kadlec, the assistant secretary for preparedness and response at the Department of Health and Human Services, called the aftermath of approval for MCM sponsors.

As part of the 21st Century Cures Act, Congress authorized the FDA to award transferable priority review vouchers (PRVs) to incentivize companies to develop MCMs. The FDA released a draft guidance Wednesday explaining how it intended to implement that PRV program. But those vouchers may not be enough.

While PRVs have worked in the past to spur the development of treatments for tropical and rare pediatric diseases, Gottlieb said other incentives may be needed for MCMs. As more PRVs enter the marketplace, the value of the vouchers is diminishing, he said.

Greatest natural threat

Getting down to specific threats, Stephen Redd, director of the Office of Public Health Preparedness and Response at the CDC, said influenza is probably the greatest natural threat facing the nation. His comment resonated as several lawmakers noted that this year marks the 100th anniversary of the 1918 flu pandemic that killed hundreds of thousands of people in the U.S. and up to 100 million worldwide.

To date, 23 flu vaccines have been developed with BARDA's assistance, said Sen. Christopher Murphy (D-Conn.). Gottlieb added that products are in development that could be universal flu vaccines.

The vaccine is one thing, Murphy said, but officials also need to ensure there are enough devices to administer the doses. He noted that the number of delivery devices don't always match the number of doses available.

The CDC is evaluating that issue, Redd said, and is looking at vaccines that require fewer doses per person or oral formulations that don't require a delivery device.

Another issue is keeping up with new influenza and other threats. Redd said the CDC works with the U.S. Department of Agriculture to track animal flu strains and diseases that could be transmitted to humans. He called it a "reactive strategy," which chafed Sen. Bill Cassidy (R-La.), who pushed for better use of big data to inform preemptive responses to potential threats.

As one way to limit the threat of animal diseases mutating to humans, Gottlieb suggested creative policy approaches to encourage the development of drugs to treat the diseases in animal populations.

Sen. Patty Murray (D-Wash.), ranking member of the committee, also stressed the need to respond to the next tragedy with foresight instead of reacting in hindsight. "We need to respond to global health crises abroad before they travel home. Diseases are not stopped by borders, or walls or bans," she said.

The HELP Committee will hold the second part of the PAHPA reauthorization hearing Tuesday. HELP Chairman Lamar Alexander (R-Tenn.) said his plan is to mark up the reauthorization bill within a few months and then move it to the full Senate.