Faced with a potential outbreak of SARS back in 2002, the United States more or less freaked out. People avoided restaurants, bars, international travel, and generally anything social. That took a big toll on the global economy: about $40 billion, according to one estimate. Yet public health officials often ignore those costs—regrettably so, according to a new study, since how the public responds to a threatened epidemic could determine whether it's best to respond early or not to respond at all.
"Far from the rational actors presented in many mathematical models, humans tend to inflate the actual risk from novel or severe pathogens, which are perceived as unpredictable and uncontrollable," write Shannon Fast, Marta Gonzalez, and Natasha Markuzon in PLoS One. This has with predictably unfortunate consequences, including riots and other violence, negative impacts to tourism, and damage to the economy as a whole. The Ebola outbreak in West Africa, for example, is thought to have cost the region hundreds of millions of dollars, and not just because of health care costs or lost productivity of those with the disease, according to a World Bank report, which concludes that "More important, [costs] arise from the aversion behavior of others in response to the disease."
Even if an Ebola outbreak wouldn't be so bad, health officials might need to react immediately and decisively, lest fears of Ebola cause as much or more economic damage than the disease itself would.
With that in mind, Fast, Gonzalez, and Markuzon took a look at how social responses, like avoiding restaurants or choosing not to travel, might play in to the overall cost-benefit analysis for responding to a disease outbreak. The team started with a model that accounts for how both disease and panic spread through social networks. They'd previously validated the model using data on 2009 H1N1 flu outbreaks in Mexico City and Hong Kong, but now they wanted to see how costs would add up in a number of hypothetical situations—and what the most cost-effective responses would be.
Analyzing their model with the aid of computer simulations, the team found that when the public feared a disease, it was best to respond to outbreaks earlier and more forcefully, regardless of how severe the disease actually was. In other words, even if an Ebola outbreak wouldn't be so bad, health officials might need to react immediately and decisively, lest fears of Ebola cause as much or more economic damage than the disease itself would.
Something odd happened, however, when the team considered how news outlets would report on efforts to contain an epidemic: Sometimes, it was most cost effective to not do anything at all. Unless the public harbors irrationally great fears of the disease—or the disease is actually dangerous—all health officials can do by intervening is attract more media attention and increase the risk of panic.
"[T]he costs of a disease outbreak are not limited to only treatment costs and disease control costs. Diseases can have much broader social impacts, including effects on the economy and social upheaval," the team writes. "This work represents a first step toward developing effective disease control measures, taking into account the indirect social costs of an outbreak."
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