While Zika certainly has the potential to be dangerous, we should be careful to not overstate the greater threat it poses given how little we know about the virus.

“The government is advising Colombian women to delay becoming pregnant for six to eight months…”

The statements of Colombian Health Minister Alejandro Gaviria in response to the Zika virus threat and echoed by other regional health leaders, caught everyone’s attention. Meanwhile, the World Health Organization – still reeling from its acknowledged failure to respond quickly to the Ebola crisis – warned of the imminent spread of the disease across South, Central and North America, suggesting the threat was likely here to stay.

Taken together, the overall message from the international health community might be interpreted: Please – no new babies for the foreseeable future, thank you.

The shock of it will raise awareness, which undoubtedly was a goal. But as a behavioural change strategy? Knowing what we know about human nature, we might applaud the ambition, but have to dismiss the recommendation’s clear detachment from reality.

One of a group of mosquito borne diseases, including West Nile, dengue and Chikengunya, evidence of Zika has been found across South and Central America as well as the Caribbean. Brazilian health officials have posited Zika may be linked to the country’s alarming rise in microcephaly cases, a rare birth defect where babies are born with abnormally small heads and underdeveloped brains. In most years, Brazil might see about 150 cases—in the past 4 months, nearly 4,000 babies have been born with the condition.

Still, hard scientific evidence of a definitive link to microcephaly is not yet available, and international scientists have argued for more research. Further, most cases of Zika result in either mild illness or no symptoms at all. Even so, the attention paid to Zika in recent weeks has been breathtaking. The media profile of even the theoretical possibility that the disease may be sexually transmitted speaks both to the thirst for Zika related information and just how little we actually know. But one thing does seem clear, the evidence of a gap between the current empirical risk assessment and the heightened levels of risk perception. So just what’s going on?

Zika is novel. Or at least, it’s novel to us. Although first discovered in the 1940s, we’ve never paid much attention to the sporadic outbreaks of the disease. Indeed, as recently noted by the Royal Society of Tropical Medicine and Hygiene, “from its discovery until 2007, confirmed cases of Zika virus infection from Africa and Southeast Asia were rare and until recently there has not been much published” about the virus. Moreover, emerging diseases always spark interest – in the case of Zika, this increased attention feeds into a broader narrative that global ecological change is introducing yet another new threat, and notably, changing all the rules. As environmental activist Bill McKibben wrote in The Guardian, Zika virus presents another “step in the division of the world into relative safe and dangerous zones, an emerging epidemiological apartheid.”

There is a fear the disease targets pregnant women. Of course, few groups tap into our collective need to protect like those who embody both the purity of childhood and the future of humankind. As the very large body of research on risk “fright factors” concludes, along with small children, pregnant women and others representing future generations are always our most sacred figures when we are dealing with health and disease.

But perhaps more than anything, it is the tragic, heart-breaking photographs of babies born with heads much smaller than they should be who, with their parents, face an uncertain future that might entail severe long-term developmental disabilities, or death. Those images – which capture our worries and our fears in an instant — exist outside of the more clinical debate on comparative risk, on existing evidence, on reasonable precautions.

All this can help explain the concern, the profile, and the collective hand-wringing. But for authorities, the actual risk communication challenge is something else. Our current understanding in Canada, for example, indicates that the threat of Zika is very low, but – truth be told – the risk is uncertain and that uncertainty is why communicating is so complicated. Indeed, as we showed in our past research on Ebola, even a remote risk of deadly contagion will not stop Canadians from becoming afraid.

Public health authorities, and the communication experts they employ, generally don’t like uncertainty. Higher levels of uncertainty tend to be correlated with weaker guidance and more diverse and contradictory expert opinion. Higher uncertainty is also more threatening to many public sector management norms – built as they purport to be around a solid evidence base for decision-making – and often lead to decisions based less on science than politics.

Similarly, we know that uncertainty relating to issues affecting the health of our loved ones or ourselves will often produce higher levels of mental distress, even a sense of hopelessness. Research confirms what most of us know from personal experience, it’s the “not knowing” which can feel unbearable.

But, of course, uncertainty is not unique to the Zika virus. In fact, it’s a characteristic of virtually every emerging public health threat. In the past, high uncertainty has been used as an excuse to not communicate, and the resulting delays not only hobbled the response but, when coupled with no openness or disclosure at all, kept the public in the dark. Increasingly, we are accepting that we will probably never have all the answers, however uncomfortable that may be. This shift to uncertainty management, coupled with the commitment to openness and transparency, helps guide how we effectively communicate about health risk.

Indeed, in situations involving heightened risk perception and weak levels of scientific certainty, authorities have to explain what is not known as much as what is known – but they also need to explain what they are doing to understand more. The imperative to qualify recommendations is vital, but they also need to go further and encourage citizens to stay actively informed. This sharing of responsibility can provide a constructive outlet for people who are anxious or worried. More importantly, it reflects the risk management ideal that calls on everyone to contribute to the co-managing of a potential threat. Further, health authorities have to plan on uncertainty lasting longer than they expect or would prefer, and need to prepare the public for this likelihood as well. This fights against the temptation to allow hope, optimism and the desire for certainty to dominate messaging. However well intentioned and desirable it may be to say “there’s nothing to fear”, or “trust us, we’re the experts,” experience has taught us over and over that the public expects authorities to maintain vigilance, and to bear the burden of doing the worrying for them while keeping them informed. It’s a delicate dance, but health officials have to know that it’s their job to expect surprises and communicate accordingly.

This brings us back to Zika virus, and the question of how to communicate its risks.

Clearly, extra vigilance is the order the day. The uncertainty of the Zika threat demands careful adherence to the precautionary principle, but also recognition that maintaining trust throughout what may be a long lifecycle of the event relies on reasonable proportionality.

Just this morning, the WHO announced it had convened an emergency committee of experts to advise on how to prevent what they describe as “explosive spreading” of the virus, and how best to communicate with affected populations and the international community. Most countries outside of the affected zone have now issued travel related guidance. The U.S. Centers for Disease Control, for example, has advised Americans thinking about becoming pregnant to avoid travel to 20 Latin American and Caribbean nations.

Canada issued its own Public Health Notice focused on travel related risk, while reflecting the fact the country is unlikely to face a domestic outbreak anytime soon. The language is measured, for example, not advising against travel for pregnant Canadians per se, but suggesting consideration of the idea.

Critics – especially those most alarmed – might see this as weak, that the fear of retaliatory trade sanctions has prohibited stronger guidance.

Perhaps that’s true, but communicating the Zika risk and its associated uncertainty demands prudence. Aggressive guidance, such as that offered by the Columbian Health Minister has undoubted shock value, but always runs the risk of being ignored by the community and eroding the fragile trust which holds public health together. But describing “the level of alarm [as] extremely high” and use of language like “spreading explosively” to characterize the behaviour of the virus will also no doubt amplify risk and contribute to contagion fear.

Increasingly, we understand that effective health risk communication is about much more than just technical risk assessment. Just as importantly, it’s about understanding and assessing risk perception. The trick, as always, is striking a balance between the two. As our knowledge about the threat of Zika becomes clearer, as the science matures, and as our understanding of public risk perception grows, we have to continually recalibrate our messaging. That artful balance between scientific analysis and the analysis of risk perception holds the key not just to effective risk communication, but to successful risk management as well.

John Rainford is director of the Warning Project, a nonprofit partnership of international practitioners, academics and consultants committed to helping governments and other organizations communicate more effectively during emergencies or other high-risk events. Josh Greenberg is director of the School of Journalism and Communication at Carleton University and leads the Communication, Risk and Public Health Research Group. He was a member of the Council of Canadian Academies Expert Panel on the Effectiveness of Health Risk Communication, and he sits on the advisory board of the Warning Project.