The 19 medical experts who attended the Pandefense 1.0 meeting in November gave a median estimate of a less than 1 percent chance that the U.S. will have adequate stockpiles of vaccines or antiviral drugs to prevent a pandemic within the next three years. The same experts gave a median estimate of 15 percent for the probability that the avian flu virus will mutate into a strain that can spread efficiently by human-to-human contact within that time. Their median worst-case estimate of the number of people who would die, should that happen, was 6 million in the United States and 180 million worldwide. Their median best-case estimates were 500,000 dead in the United States and 20 million worldwide.
"It surprised me that they thought it was going to be this bad," said Wändi Bruine De Bruin, lead author of the study and research faculty member in the Department of Social and Decision Sciences at Carnegie Mellon.
The survey also included 17 non-medical experts from a variety of fields who were more pessimistic about the likelihood of human-to-human transmission, giving a median 60 percent chance that it would occur within three years. They did, however, have more faith in medical science, giving a median 15 percent chance of the United States having enough vaccine and a 30 percent chance that the nation would have enough antiviral medications to halt a pandemic.
"The medical experts' estimates suggest this is a bigger risk than anything else we are fa cing," said Baruch Fischhoff, a study co-author and the Howard Heinz University Professor of Social and Decision Sciences and Engineering and Public Policy at Carnegie Mellon.
Both the medical and the non-medical experts agreed that the greatest hope for mitigating the effects of an avian flu outbreak among humans lies in heightened global surveillance and, should the virus become pandemic, hand washing, mask wearing and social distancing. Unfortunately, the efficacy of such strategies in preventing the spread of infectious diseases has not been extensively studied, Bruine de Bruin said. Although the federal government has expressed a commitment to open communication about these risks, its messages have not yet been scientifically evaluated, according to Fischhoff.