Pandemic Influenza Planning, United States, 1978–2008

John Iskander

, Raymond A. Strikas, Kathleen F. Gensheimer¹, Nancy J. Cox, and Stephen C. Redd

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (J. Iskander, R.A. Strikas, N.J. Cox, S.C. Redd); Public Health Consultant, Cambridge, Massachusetts, USA (K.F. Gensheimer)

Abstract

During the past century, 4 influenza pandemics occurred. After the emergence of a novel influenza virus of swine origin in 1976, national, state, and local US public health authorities began planning efforts to respond to future pandemics. Several events have since stimulated progress in public health emergency planning: the 1997 avian influenza A(H5N1) outbreak in Hong Kong, China; the 2001 anthrax attacks in the United States; the 2003 outbreak of severe acute respiratory syndrome; and the 2003 reemergence of influenza A(H5N1) virus infection in humans. We outline the evolution of US pandemic planning since the late 1970s, summarize planning accomplishments, and explain their ongoing importance. The public health community’s response to the 2009 influenza A(H1N1)pdm09 pandemic demonstrated the value of planning and provided insights into improving future plans and response efforts. Preparedness planning will enhance the collective, multilevel response to future public health crises.

Historical Background

Influenza pandemics occur when an animal influenza virus to which humans have no or limited immunity acquires the ability, through genetic reassortment or mutation, to cause sustained human-to-human transmission leading to community-wide outbreaks (1). The existence of a pandemic is currently determined by the extent of disease spread, not by the lethality of the disease caused by the novel virus (2). During the twentieth century, influenza pandemics occurred in 1918, 1957, and 1968. The 1918 pandemic, known as the “Spanish flu” pandemic, was unique in that the highest number of deaths was among young, healthy persons. Excess mortality in the United States during the 1918 pandemic was estimated at 546,000 deaths (3). The pandemics in 1957 and 1968, although associated with death rates greater than those for seasonal influenza epidemics (3), were far less devastating than the 1918 pandemic.
Before 1976, public health planning for pandemics primarily occurred in response to detection of a novel influenza virus. This reactive mode continued despite the framework outlined in 1960 by US Surgeon General L.E. Burney for responding to the next pandemic. That framework involved recognition of the pandemic (i.e., surveillance), manufacture and distribution of vaccine, and identification of research needs (4). Large-scale infectious disease response planning may have been hampered by the tacit assumption that the government’s public health resources were better directed to other priorities.
In January 1976, a novel swine-origin influenza virus emerged among soldiers at Fort Dix, New Jersey (5); 1 soldier died, and an estimated 230 were infected. The emergence of influenza virus of swine origin at Fort Dix led to the decision to mount a national immunization program (6). The following events occurred subsequent to this decision: Congress funded vaccine production and liability indemnification of manufacturers, vaccine was produced, a mass immunization campaign commenced, and 45.65 million persons were vaccinated in the United States (7). Initial fears that the virus would cause a pandemic did not materialize: sustained transmission did not occur outside of Fort Dix. The vaccination campaign began in October 1976 and was halted in December because of initial reports of a rare association between the so-called “swine flu” vaccine and Guillain-Barré syndrome; the association was later confirmed (7). An influential policy review of the “swine flu affair” (i.e., the campaign to immunize the US population against a possible epidemic) identified several critical needs for future planning: 1) a more cautious approach to interpreting limited data and communicating risk to the public, 2) greater investment in research and preparedness, 3) clearer operational responsibilities within the federal government, 4) clear communication between planners at all levels of government, 5) strengthened local capacity for plan implementation, and 6) improved mechanisms for program evaluation (8).
In November 1977, separate from the Fort Dix outbreak, a strain of human influenza A(H1N1) virus reemerged in the former Soviet Union, northeastern China, and Hong Kong, China, even though the virus had not circulated since 1957. This strain primarily affected young persons, and caused mild illness (9). The virus was found to be closely related to a 1950 A(H1N1) strain but dissimilar to the 1957 strain, suggesting that this 1977 outbreak strain had been preserved since 1950 (9).
The confluence of fears of a possible pandemic in 1976 followed by the reemergence of a new strain of circulating seasonal influenza virus in 1977 led to focused pandemic planning efforts in the United States. The primary purpose of this article is to describe US pandemic planning during 1978–2008, just before the onset of the influenza A(H1N1)pdm09 pandemic in April 2009. We believe that understanding the historical and policy context within which the A(H1N1)pdm09 pandemic occurred is helpful in assessing the implications of pandemic planning for responses to future pandemics and for ongoing infectious disease preparedness efforts.