The Current Outbreak of Swine Flu in the United States

April 28, 2009

The current outbreak of swine flu in the United States, Mexico, and other countries has raised concerns among policymakers and public health experts about the possibility of a pandemic and about the nations ability to blunt the effects of such an event. (A pandemic arises when a new virus emerges that has not previously circulated among the human population; that virus causes significant illness in humans; and the virus is easily transmitted from one person to another.) Beyond the human suffering that a pandemic would engender, policymakers are also concerned about the potential for economic disruptions that might be layered on top of an economy already in recession.

The current outbreak is evolving rapidly, and the risk that it poses is not yet fully understood. The World Health Organization has not declared the current outbreak to be a pandemic. However, if the current strain were to cause a pandemic, it has the potential to slow the pace of the economic recovery that CBO expects to take hold later this year. The consequences of past episodes provide a basis for assessing the potential seriousness of a pandemic, particularly in light of the current economic downturn. In a May 2006 analysis, CBO considered the possible economic effects of a range of influenza pandemics. On the basis of an analysis of past pandemics, CBO devised two scenarios to illustrate the possible economic effects of an influenza pandemic. In a mild-pandemic scenario, resembling the pandemics in 1957 and 1968, about 75 million people would be infected in the United States, and about 100,000 of them would die (in a typical year seasonal influenza causes about 36,000 deaths in the United States). In that scenario, the pandemic would reduce real (inflation-adjusted) gross domestic product (GDP) by about 1 percent relative to what would have happened without the pandemic. In a more severe scenario, roughly similar to the 1918-1919 Spanish flu outbreak, about 90 million people would become infected, and 2 million people would die in the United States; in CBOs estimation, real GDP would be about 4-1/4 percent lower over the subsequent year than it would have been had the outbreak not taken place. Of course, there have been widespread changes since 1918 that may change the severity of an outbreak. Faster international travel may mean faster transmission, but better antibiotics mean less risk of complications which were often proximate causes of death in the 1918-1919 outbreak.

In a paper released in September 2008, CBO focused on the governments role in the vaccine market that stems from a 2005 plan by the Department of Health and Human Services (HHS) to prepare for and combat an influenza pandemic. That plan, although developed in response to the threat of the H5N1 virus, or avian flu, sheds light on the nations ability to respond to the current swine flu outbreak and will probably be the subject of public discussion in the coming months.

Because of the time it takes to produce a flu vaccine using current technology, a pandemic could circle the globe more quickly than vaccines could be produced. For the next several months, the nations response to the swine flu outbreak will be limited to measures that might reduce the spread of the virus through social distancing, strategic use of antiviral medications from existing stockpiles, and the capacity of the existing public and private health systems to treat infected people.

To improve the nations capacity to respond to a pandemic, HHSs plan calls for an enlarged role of the federal government in promoting private-sector development of new vaccines, expanding the capacity of the industry to manufacture them, and procuring stockpiles of prepandemic vaccines. (Prepandemic vaccines are developed from strains that public health officials believe have the most potential to cause an influenza pandemic.) The prepandemic vaccine that has been stockpiled to date is an H5N1 vaccine and is unlikely to offer protection against the current swine flu outbreak.

HHSs plan has multiple objectives, including to:

  • Increase manufacturing capacity by refurbishing and expanding plants that produce vaccines using traditional egg-based processes (developed in the 1940s) and increasing the availability of more costly cell-based manufacturing technology and
  • Make vaccines available more quickly. The plan takes two approaches to meet this objective. First, it calls for stockpiling a relatively small amount of prepandemic vaccine that could diminish the worst effects of a pandemic by protecting particularly vulnerable groups and first responders. However, none of the stockpiled vaccine is likely to provide protection against the current swine flu outbreak. Second, it aims to develop so-called next-generation vaccines that can be produced more rapidly than currently available vaccines to more efficiently meet long-term needs.

Ongoing research has changed the environment in which HHSs plan was originally formulated in at least one important regard. Adjuvantssubstances that may be added to influenza vaccines to reduce the amount of active ingredient (called antigen) needed per dose of vaccineare showing promise in clinical trials in the United States; some of them have been approved for limited uses in Europe. If a safe and effective adjuvanted swine flu vaccine can be developed, manufacturers may be able to provide enough vaccine for the entire U.S. population within a span of several months thereafter.

Specifically, CBO reached the following conclusions in its September 2008 paper:

  • The manufacturers of currently approved vaccines made in the United States cannot produce vaccines of sufficient effectiveness, in sufficient quantities, or in the time required to meet public health needs in the event of an influenza pandemic.
  • In the short term, adjuvanted vaccines offer the best hope for achieving HHSs goal of having enough vaccine to protect 300 million people within six months of the outbreak of an influenza pandemic. The manufacturing capacity that is needed to produce pandemic-influenza vaccine exceeds what is required to make seasonal vaccine; ongoing federal support may be required to meet and maintain the necessary capacity.

Adjuvants developed since 2005 could substantially reduce the amount of antigen needed per dose, raising the question about whether HHSs current policy is the most cost-effective approach to meeting its vaccine-production goals. In light of this, the September 2008 paper briefly examined several other options to consider if adjuvanted vaccines prove successful, including reducing the capacity targeted for manufacturing cell-based influenza vaccines while expanding resources available to support the development of next-generation vaccines, entering into advance supply agreements (an approach used by several European nations that allows countries to make advance payments to manufacturers in exchange for a guaranteed supply of vaccine in the event of a pandemic), and modifying the size of the planned vaccine stockpile.