During outbreaks of serious infectious diseases, many people closely follow media reports and, as a result, take precautions – such as staying home, getting vaccinated, avoiding crowds, using disinfectants, canceling travel plans and wearing face masks.
Known as “self-isolation,” these precautions significantly can reduce the severity of an outbreak, according to mathematical modeling done by researchers at the Georgia Institute of Technology and Marshall University in Huntington, W.Va.
“The more forcefully the media provides information about pandemic infections and deaths, the more the total number of infections is reduced,” said Howard Weiss, a professor in the Georgia Tech School of Mathematics. “Media coverage also reduces the maximum number of infections at any particular time, which is important for allocating the resources needed for treating infectious diseases.”
The benefit of publicly reporting disease outbreaks seems obvious, and public health officials in the United States have a policy of regularly communicating with the news media about such incidents. But according to Weiss, not all world governments choose to communicate so well – and nobody had used rigorous mathematical techniques to study the impact of that communication before.
Adjusting the Model
Epidemiologists use the S-I-R model to anticipate the effect of disease outbreaks. The basic model places individuals into one of three groups signified by each letter of the acronym:
• Susceptible individuals, who are vulnerable to the disease;
• Infected individuals, who have the disease;
• Removed individuals, who have been vaccinated, have isolated themselves from the population, have already recovered from the disease – or have died.
Weiss and collaborator Anna Mummert, an assistant professor of mathematics at Marshall University, modified that model to take into account ways that individuals could move from the susceptible group to the removed group without passing through the infected group. By self-isolating as a result of news media warnings, they reasoned, individuals could move directly into the removed class because they are no longer susceptible.
“On a chart showing the number of infected people at any one time, as you increase the intensity of the media coverage, you substantially decrease the number of infections,” Weiss noted. “We are assuming that people self-isolate at a rate that is proportional to the amount of media coverage, though we would like to study that in more detail.”
The sooner the media coverage of a pandemic begins, the fewer individuals ultimately will be infected. But Weiss said the model shows that almost any media coverage is helpful at reducing the extent of a pandemic.
“Telling the public always helps, but the longer you wait, the less it helps,” he said. “If you wait long enough, the effect of media coverage is essentially negligible.”
Weiss acknowledges that strong communications about such dreaded diseases as Ebola could create public panic. In those rare cases, public health officials must weigh the benefits against the risks.
“In general, our advice to public health officials anywhere in the world is not to hold back,” he added. “They should get out the news about infectious disease outbreaks loudly and quickly. It’s clear that vigorous media reporting can have a substantial effect on reducing the impact of an outbreak.”
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