The explosive spread of the Zika virus has captured our attention and dominated headlines. Of particular concern is the possible link between Zika virus infection and microcephaly. Meanwhile, worries about Ebola have diminished, with the World Health Organization declaring an end to the Ebola outbreak in West Africa. The frenzy that the Ebola virus generated in the United States during the fall of 2014 has become a distant memory. What lessons can we learn from our reaction to the Ebola threat, and how can we apply these lessons to Zika and future epidemics?
In many instances, our response to Ebola was irrational and over the top. We had scenes of schools being shut down for dubious reasons, cruise ships prevented from docking, images of workers “disinfecting” public spaces including bowling alleys, and mandatory quarantines for asymptomatic healthcare workers returning from West Africa. There is no denying that Ebola is a deadly disease, with a fatality rate of approximately 50% in infected individuals. However, since Ebola is not an airborne or insect-borne virus, the chances of an epidemic in the United States were essentially zero. Indeed, the risk of death from the influenza virus or the West Nile virus was much higher.
This overreaction to small risks is nothing new. Humans are terrible at assessing risk, routinely overestimating risks such as deaths due to shark attacks. According to psychologists, one reason for risk misperception is the “availability heuristic,” a concept pioneered by the Nobel laureate Daniel Kahneman and the late Amos Tversky. “Availability” refers to the ease by which we can recall examples of risky events. Risks that are easily recalled (often due to extensive coverage) are overestimated while risks under our radar are underestimated.
How should we deal with this misperception of risk? Some feel it is acceptable to respond to risks with seemingly irrational actions — if those actions calm public fears. After all, while our fears may be irrational, they are still real. This approach is similar to the “monster spray” that parents give small children to combat fear of the dark. Harmless aerosols that kids can spray under their beds get rid of the “monster” hiding there. Similarly, irrational public actions may still be justified by acting as an “adult monster spray” for our anxieties.
Outside the childhood bedroom, such attempts to contain fear are misguided and even dangerous. First, healthcare is mostly a zero-sum game, with limited resources. Excessive attention to a small risk will take away resources from larger risks. Doctors and nurses would waste valuable time preparing and training for improbable scenarios, instead of preventing and treating diseases that are real threats. Second, draconian measures such as quarantining asymptomatic, low-risk healthcare workers could result in the loss of crucial expertise — a perilous measure. Finally, far from calming fears, a disproportionate public response could backfire, exaggerating the public’s sense of danger.