The Zika Freaka Is Teaching Some Great Lessons About Risk Perception

A friend of mine, an intelligent highly regarded science journalist, recently decided to cancel a vacation to Puerto Rico with his wife and kids. Because of concern about Zika virus.

Another friend, an expert in ecology and one of the most highly regarded professors at Harvard, just canceled a talk he was scheduled to give at a conference in Sao Paolo Brazil this summer. Because of fear of Zika virus.

These decisions are worth reflection for a couple reasons. First, they were made by smart people...scientifically smart people. Second, the World Health Organization and CDC are pretty clear that Zika freaks them out because of the link between the virus and microcephaly, children born with shrunken brains or skulls if their moms had Zika while they were pregnant. This was not a risk my friends had to worry about.

So why their Zika freakout? My science journalist friend noted that Zika has also been associated with neurotrophic diseases (of the brain and nervous tissue) including Guillain Barre disease, an inflammation of the brain that in rare cases arises after infections. But Guillain Barre arises, rarely, after all sorts of infections , including dengue fever, which has been widespread in Puerto Rico since 1963. That hadn't stopped them from planning a vacation to Puerto Rico. So why Zika?

My other friend, the Harvard professor, said he was worried because "scientists still don't know...there is a lot of uncertainty..." "But what about all the cases of dengue and chikungunya virus in Sao Paolo?" I asked. "They didn't scare you off. And what about all the evidence about Zika from how it has affected people around the world for decades," I added. "Most people bitten by an infected mosquito don't show any symptoms, and among the small percentage of people who do, you get usually mild flu-like symptoms - aches and fever and sluggishness - for a few days up to a week...and that's it. The only thing scientists aren't sure about is the link to what it does to the fetus. And you aren't a fetus."

My friend, who knows I teach risk perception at Harvard, smiled and sheepishly acknowledged "Maybe I sound irrational, I know. But it just feels scary, all that uncertainty, so I decided to err on the safe side."

Neither of my friends erred, of course. Their decisions weren't right or wrong, smart or dumb, rational or irrational. They were the right decisions for them, because to them those choices felt right, felt safe, despite what the bulk of the evidence may say. But their choices do teach an important lesson. Decisions about risk and how to keep ourselves safe aren't about the evidence alone, even for intelligent scientifically literate people. Risk perception is much more about how we feel than what the facts alone may say. Uncertainty makes risks feel scarier. So does lots of attention, like Zika's been getting.

Choices about risk based on emotion as much as cold hard reason are not automatically wrong/dumb/irrational. In fact, they usually help protect us. What's the harm in being careful? Like they say, better safe than sorry. But there can be real danger in these choices too. They sometimes produce a Risk Perception Gap...when we worry too much, or not enough, and do things that feel safe, but aren't. My science journalist friend and family only missed a vacation, and my professor friend missed a speaking opportunity (and maybe an honorarium check). But what about people who are too afraid of, say, human-made vaccines, so they don't inoculate their kids? Or people who are too afraid of flying, so they drive...a riskier way to travel? What about people who aren't afraid enough of texting while they drive, or not afraid enough of obesity to diet and exercise, or not afraid enough of the sun to wear sun screen or a hat, or not afraid enough of climate change to press our leaders to act? Those choices all feel right too...but they expose the people making them to real danger.

Examples of the Risk Perception Gap and its dangers are everywhere. So my friends' choices offer a gentle warning. We need to work to get more information - from credible sources - before making a choice about a risk, and we need to work hard to give that information a fair voice as our brain figures out what choice to make. Emotions and instincts will still speak loudly as we make our decisions, but keeping our feelings from dominating the decision might lead to a choice that actually keeps us safer. And after all, that's the goal.