Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, has a ready answer when asked to name a biological threat he especially dreads: the flu.

“Looming there in the background is the possibility of there being of a pandemic influenza, and that’s what we prepare for continually,” Fauci told members of the House Energy and Commerce Committee last month.

As Congress this week addresses a White House request for $6.2 billion to combat the Ebola virus, public health experts see lessons for lawmakers in the early, stepped-up spending to ward off a possible flu pandemic. More than $12 billion has been appropriated to fight the flu since 2005, money used to help build new vaccine production sites and spur the introduction of new kinds of flu shots to combat routine annual influenza that claims thousands of lives even in the mildest of seasons.

The specter of the 1918 flu pandemic — which claimed at least 50 million lives, more than the death toll for World War I — has remained a driving force in public health while medical leaders scramble to address the world’s deadliest Ebola outbreak, in which more than 6,000 of the 17,000 people infected with the virus so far have died.

“Influenza is a virus that has caused pandemics in the past and has the potential to do so again,” University of Texas researcher Catherine L. Troisi said at an October House hearing on the Ebola outbreak. “The virus can mutate so much that it’s like a new virus no one has experienced before, and so no one is immune.”

The nation’s progress over the past decade in terms of an improved supply of flu vaccine and the science involved with its production is a “success story,” despite the predictable missteps with the 2014-15 shots, said Marcia Crosse, director for health care at the investigative arm of Congress, the Government Accountability Office. The Centers for Disease Control and Prevention said last week there’s a mismatch between a form of the virus targeted by the vaccine and a strain so far observed in samples. As a result, the flu shots for this season will likely be less effective than had been hoped.

“I wouldn’t knock them too much for not perfectly predicting the match,” Crosse told CQ Roll Call. “They have to make these decisions several months in advance because of the time it takes to make the vaccine.”

Take the Shots

The director of the CDC, Thomas R. Frieden, still strongly urges Americans to take advantage of what he calls an “ample” supply of 2014-15 flu shots, as they offer protection against other forms of the virus.

About a half dozen companies combined will produce 151 million to 156 million doses of influenza vaccine for the current season, according to the CDC. This is a markedly different market for flu vaccines than the one in the 2004-05 season, when officials at the CDC and Food and Drug Administration had to rush to address a severe shortfall in the vaccine supply. Only about 57 million flu shots were distributed, or about half the expected number for the season, according to a 2013 GAO report.

The 2004 disruption went beyond the routine hitches often seen with production of the annual shots, such as the initial delays with some supplies this October. A decade ago, there were only three firms making flu shots, which were not considered an attractive product line for big drug companies. This fragile supply chain was badly disrupted when United Kingdom regulators in October 2004 suspended the license of a Chiron Corporation plant that made flu shots for export to the United States.

Congressional hearings were called to examine why the United States was not better equipped to supply its citizens with flu shots, a staple product of public health. Federal officials, including Fauci, then stressed the need for more investment to begin to shift production away from the old-fashioned approach, which relied exclusively on eggs to make flu shots.

A decade ago, Fauci was arguing for a shift toward more advanced production methods, using cells and recombinant DNA technology, when he told a House committee, “We have heard a bit about egg-based cultures. These are tried and true and have served us well. But they have little surge capacity and there is a risk in them, as we have seen what happened with the contamination in the Chiron plant.”

A month later, Congress gave the Bush administration its requested $100 million for bolstering flu vaccine production, including purchases of vaccine as part of an appropriations law. In 2005, when a worrisome form of H5N1 avian flu emerged, Congress provided about $6 billion for the avian and pandemic flu efforts. A tough 2009 flu season paved the way for the appropriation of another approximately $6 billion the following year for vaccines, tests and medical surveillance tools that would be needed in the case of a pandemic.

These funds reinvigorated what had been a scientific backwater for influenza research.

New Technology

The flu shots available for 2014-15 include breakthrough products developed by companies in partnership with the Department of Health and Human Services. Protein Sciences Corp.’s Flublok, approved last year, is the world’s first flu shot made through the genetic engineering known as recombinant technology. Novartis AG’s Flucelvax, approved in 2012, is grown in cell cultures.

These more flexible manufacturing approaches are at the heart of a more than $400 million federal effort to work with industry to develop three centers designed to rapidly make new vaccines in case of a pandemic. With target dates staggered between 2017 and 2020, each of these centers is intended to be capable of producing 50 million doses of vaccine within four months of receiving a pandemic strain sample, with the first doses made available to HHS within 12 weeks, according to a GAO report. Such efforts may aid rapid production of an Ebola vaccine if one is developed, Crosse said.

Richard Hamburg, deputy director at the Trust for America’s Health, where he has helped with a campaign that calls for a national infrastructure that could fight a flu pandemic, said lawmakers have responded well overall once they saw a need to draw private companies into the field of influenza.

“Domestic capacity was limited and vulnerable” a decade ago, Hamburg said. “The strides that have been made can definitely be tracked to the large congressional investments.”