March: Biodefense & food supply safetyPandemic flu may be well mitigated until vaccine is available

Published 12 March 2008

New study shows that high levels of compliance, ascertainment, and social distancing would make it possible to mitigate a flu pandemic until a vaccine is available

An outbreak of pandemic influenza in the United States could be mitigated with prompt implementation of social-distancing measures combined with antiviral treatment and prophylaxis until a vaccine is available, according to new findings published in the online Early Edition of PNAS. Working closely with federal officials, three teams of researchers in the United States and England collaboratively studied various intervention combinations to guide national pandemic planning. The three research teams and an informatics group which participated are part of the Models of Infectious Disease Agent Study (MIDAS) Network, an effort funded by the National Institute of General Medical Sciences, or NIGMS. The lead author, M. Elizabeth Halloran, M.D., D.Sc., and co-author Ira M. Longini Jr., Ph.D., both researchers at Seattle-based Fred Hutchinson Cancer Research Center and professors of biostatistics at the University of Washington, use mathematical and statistical methods to study the natural course of infectious diseases. Prior to publication, Longini presented the findings at the White House and at the Institute of Medicine. “The federal government wanted three separate infectious-disease-modeling groups working on the same problem just to make sure the results were robust, since this data would be used to inform national pandemic planning,” Longini said. “We got the highest level of input.”

A vaccine was unavailable at the time the study began, so the researchers were asked to focus on analyzing the effectiveness of a combination of antiviral and social-distancing interventions, such as closing schools, in thwarting a flu pandemic. Previous similar modeling studies had shown that even a low-efficacy vaccine would be quite helpful in slowing a pandemic if it were available. “The good news was that all three of the disease-modeling groups involved in the study found that an outbreak of pandemic flu similar to the pandemic of 1918 could be mitigated if these measures were implemented quickly,” Halloran said. Halloran, Longini, Shufu Xu, a computer scientist in their group, and collaborators at the Los Alamos National Laboratories constituted one of the research teams. A second group included researchers at Imperial College in London and the University of Pittsburgh. A third group included investigators at the Virginia Bioinformatics Institute at Virginia Tech in Blacksburg, Virginia.

To conduct the study, the researchers used three separate but similar computer models to calculate the spread of influenza within a population similar to that of Chicago, with approximately 8.6 million people. Members of this