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Zika Risk Communication:
WHO and CDC Are Doing a
Mostly Excellent Job So Far

Question from Faye Flam: In the case of Ebola, some public health officials expressed great certainty about the likely spread of the virus, though there were considerable unknowns. With Zika, again, are there unknowns that have been glossed over? Could the public health community be more straightforward with the press about the unknowns and the uncertainties?

Top U.S. public health officials have been extremely straightforward about Zika unknowns and uncertainties, calibrating their statements to convey their own levels of uncertainty to the public without overstatement or understatement, and without overconfidence.

CDC is doing spectacularly good uncertainty risk communication. The goal should be to create the same level of uncertainty in the audience as in the source. CDC’s Anne Schuchat and Lyle Petersen and NIAID Director Anthony Fauci are carefully conveying their own levels of uncertainty, neither overstating nor understating what is known and unknown about Zika.

And mainstream science reporters seem to be capturing that uncertainty pretty well in how they are quoting and paraphrasing these expert officials.

Consider for example these excerpts from CDC’s January 28 Zika telebriefing, with our characterizations of the quotes.

Statement of principle about how CDC proposes to discuss uncertainty:

“We’ll talk about what we know about the Zika virus, what we don’t know, and what we’re working hard to find out about. We know many people are concerned or scared, and we want to answer your questions with what we do know now.”

Very high degree of certainty:

“…we expect more countries to be affected.”

Getting close to certainty:

“…increasing lines of evidence suggest that some women who are infected with Zika during their pregnancy may go on to deliver a baby with a serious brain injury.”

“Laboratory tests at CDC strongly suggest a link between Zika infection and some of the poor pregnancy outcomes.”

Above average level of certainty, but with caution not to be overconfident:

“It’s possible, even likely, that we will see limited Zika outbreaks in the U.S.”

“Our experience with dengue and chikungunya and the different living conditions lead us to believe that any outbreaks of Zika in the continental U.S. will likely be limited. Of course this virus is fairly new to the Americas and we will remain vigilant.”

Plenty of uncertainty; neither outcome would be surprising:

“CDC is currently working with public health officials in Brazil to investigate whether there’s any link between Zika infection and Guillain-Barré.”

Complete uncertainty:

“We don’t yet know what other outcomes might be associated with Zika infection during pregnancy.”

We couldn’t ask for better uncertainty communication than we are getting from CDC and NIH about Zika.

Question from Faye Flam: Are scientists erring too much on the side of scaring people or are they being too reassuring over a threat that’s not well understood?

We would rephrase this question:

“Are scientists trying to alarm people more or less than they themselves are alarmed about Zika?”

Our best guess is that most scientists and public health officials are trying to replicate in the public the level of alarm they themselves actually feel, just as they are trying to replicate their level of uncertainty.

It looks to us like they are scaring people duly, not unduly.

Based on what they know and suspect, they are duly warning those most at risk: pregnant women who were or may have been exposed to Zika. And they are duly warning pregnant women who are considering risking such an exposure by traveling to countries where Zika is widespread. They are conveying – with appropriate anguish at times – their enormous uncertainty about all aspects of the Zika risk for the unborn children of pregnant women.

They are duly reassuring everyone other than pregnant women that Zika infection is usually mild or asymptomatic, while cautioning that some infections may lead to Guillain-Barré syndrome. And they are duly reassuring even pregnant women in places where local Zika transmission is unlikely to be widespread that their fetuses are almost certainly safe.

They are not trying to arouse excessive fear in women who are pregnant or trying to get pregnant. They are trying to arouse appropriate fear about a potentially cataclysmic pregnancy outcome. In the face of massive uncertainty, they are trying to alarm these women just enough that they will be highly motivated to take the recommended precautions.

There are always some commentators, public health experts, and even communication experts who long for the Holy Grail of risk communication: informing people, educating people, and motivating precautionary behavior without scaring anyone. If we were all Mr. Spock from Star Trek, that would work just fine. But since we are actually normal human beings, we find scary things scary.

It is extremely difficult to prevent people from being frightened about realities that are legitimately frightening. It’s even more difficult to prevent people from being frightened while simultaneously convincing them to take precautions. If you want people to take precautions, we endlessly tell our public health clients, you have to be willing to frighten them, or at least to tolerate and guide their fears instead of trying to suppress their fears.

What’s harder still for our public health clients to understand and accept is that they must tolerate and guide not only people’s appropriate fears, but also people’s excessive fears – especially early in the lifecycle of a new risk.

Fear – often excessive fear – wells up in us normally when we first hear about a new, scary risk. Using our imaginations is part of how we incorporate our new knowledge at first. This is the “Oh My God” phase of learning about a new risk.

We call this the “adjustment reaction.” It is a temporary overreaction. And it is often the most teachable moment if officials treat it with respect instead of contempt.

The problem is that some people, like experts and science reporters, are ahead of everybody else on the learning curve about a new risk. More often than they like to remember, much less admit, they too went “Oh My God” when they first heard about the risk. But they’re more accustomed to it now, and responding more professionally. So when the public has the same “Oh My God” reaction, they often accuse the public of hysteria, irrationality, or panic.

As risk communication experts, we always recommend that officials scare or reassure people proportionately to the risk. And we recommend that they tolerate and guide people’s tendency to have a briefly disproportionate response to the risk.

And in the face of massive uncertainty, officials should err a bit on the alarming side rather than the reassuring side. Since you can’t count on getting it exactly right, it is better to generate a bit too much precaution-taking rather than a bit too little.

Question from Faye Flam: The WHO is raising alarms and CDC is issuing reassurances. What should we make of this?

WHO and CDC speak to different audiences. WHO is the World Health Organization, an international agency with a global mission. CDC is a U.S. government agency; despite extensive worldwide activities, it is focused on the U.S.

WHO messaging

The risk of Zika is greatest in developing countries in tropical climates – where mosquitoes flourish, and where mosquito control and human birth control are mostly rudimentary. With the goal of reducing the number of affected babies in these poor countries, WHO is appropriately working to sound the alarm, trying to encourage precautions and research (and financial support for precautions and research).

It is arguable that some public comments coming out of WHO are a little more alarmist – in tone if not in content – than would be optimal. For example, Peter thinks that WHO Director-General Margaret Chan might have chosen to tone down her statement that the level of alarm about Zika is “extremely high.” “High” would have been sufficient, he says.

Jody disagrees; she thinks the “extremely high” level of alarm expressed by WHO is not excessive. The apparent rate of recent microcephalic babies among all live births in certain Brazilian states such as Paraiba is far higher today than the rate of Congenital Rubella Syndrome (CRS) babies in the same Brazilian states during epidemics early on in the rubella vaccine era – and that lower rate of profoundly defective newborns was a cause of high (even extremely high) public health concern then.

And it is unarguable that Zika has “spread explosively” in Latin America, just as WHO said.

The same accusations of alarmism have been directed at the Pan-American Health Organization (PAHO), the WHO regional office responsible for the countries where Zika is the biggest current health threat. Again, it’s arguable in some cases. For example, PAHO officials might have been clearer and more insistent that their guesstimate of three to four million cases in the next year referred to three to four million Zika infections, most of them asymptomatic – not three to four million Zika illnesses and certainly not three to four million babies with profound birth defects like microcephaly.

But some people have criticized as alarmist the “three to four million” guesstimate itself. We both consider that accusation unfair.

The guesstimate is based on seat-of-the-pants reasoning from highly uncertain estimates of current case numbers, plus somewhat less uncertain estimates of the way previous mosquito-borne viruses have spread in the region.

For some years now we have been observing “the numbers game” that public health officials and media play about novel infectious diseases. It’s a game the officials can’t win. The media demand that officials give them numbers, even in the absence of good data. So the officials do their best to come up with numbers, accompanying them with careful explanations that the numbers are very, very uncertain. And then the officials get creamed when the numbers turn out too high or too low – or even before the numbers turn out too high or too low.

It might have helped a little for WHO and PAHO to insist aggressively on their uncertainty – to “proclaim uncertainty” instead of merely acknowledging uncertainty. It might have helped a little, for example, to apologize in advance that the highly uncertain numbers sound pretty scary; and that the highly uncertain numbers are based on seat-of-the-pants reasoning grounded in past experience of other mosquito-born viruses and little bits of knowledge about this one; and that the highly uncertain numbers will inevitably turn out wrong, either too high or too low. And it might have helped a little to point out that even uncertain numbers are better than no numbers at all as a basis for deciding how much effort/money/resources to put into mitigating the risk. And then it might have helped a little to apologize again for scaring people, and for turning out wrong.

We have heard some people say that WHO is at risk of overreacting to Zika in 2016 because it underreacted early on to Ebola in 2014 and doesn’t want to repeat the same error. They typically attribute the Ebola underreaction to WHO’s earlier alleged overreaction to H5N1 bird flu (in birds) in 2004 and to the swine flu pandemic in 2009.

We have also heard the opposite complaint, that WHO is late again, as it was with Ebola, in responding to Zika.

While there is always the risk that WHO will tend to fight the last war, so far WHO’s communications about Zika look about right to us, proportionate to the Zika threat.

And if it turns out that WHO is overreacting a little, that’s okay with us. It is not possible to determine ahead of time how big a deal an emerging health crisis will eventually turn out to have been. Unable to be confident of guessing right, crisis communicators have to decide which criticism they prefer. Do they want to risk being accused of scaring people unnecessarily if the crisis turns out less horrific than expected, or even fizzles altogether? Or would they rather risk being accused of abandoning victims to unnecessary tragedies by failing to take the crisis seriously enough until too late? Whether a health agency is thinking about the public’s welfare or its own reputation, erring on the alarming side is wiser than underreacting.

If you overreact and over-warn people, and turn out wrong, they scoff at you. If you underreact and under-warn, they fire you and accuse you of killing babies. Either way, you’re likely to be called to testify before government committees.

So WHO communications are rightly focused on telling the world, and especially the world’s governments, that Zika deserves urgent attention. Meanwhile, WHO is doing everything it can to stimulate and coordinate desperately needed Zika research, to start answering crucial unanswered questions – and WHO communications are trying to keep us all apprised of what is and is not known, and of what steps are being taken to fill in the gaps.

One sign that WHO is taking Zika very seriously: It reassigned its top polio eradication official, Bruce Aylward, from polio to Zika – after first reassigning him to Ebola when WHO finally ramped up its Ebola response.

If we were advising WHO, we would advise it to keep emphasizing how serious Zika looks so far and how seriously WHO is taking it. That is and should be its main message.

But we would also advise WHO to communicate more strongly the possibility of the “fizzle scenario” – for example, that many or even most of the microcephaly cases identified in Brazil might turn out not to be microcephaly, or not to be Zika-related, or not to be a significant increase from Brazil’s baseline rate in previous years. Some WHO officials are doing this, but it needs to turn into a mantra that is frequently proclaimed, not merely acknowledged now and then.

We would even advise WHO officials to say that WHO was wrong about the H1N1 swine flu pandemic (wrong not to stand down sooner from its early appropriate warnings) and wrong about Ebola (wrong to minimize its severity for far too long – for example, insisting that it was not an epidemic as late as April 2014). So, officials should say, we may turn out wrong about Zika too.

Still, the fizzle scenario should be a secondary theme. The main messaging task for WHO right now isn’t to reassure the world. It is to warn the world while also acknowledging that the warning may turn out to have been excessive.

There are some ways in which WHO might appropriately decide to sound even more alarming. For example, we don’t think it has said anything about whether the Zika emergency might justify reconsideration of banned pesticides like DDT.

But on the basic facts and suspicions about Zika and the urgent need to learn more, we think WHO (with occasional exceptions) is being appropriately alarming, not excessively alarmist.

CDC messaging

We don’t actually think you are right that CDC officials (and other top U.S. officials, such as Tony Fauci at NIH) are “issuing reassurances.” It’s hard to raise an alarm much higher than warning pregnant women not to travel to an ever-increasing number of places.

The only aspect of Zika about which CDC sounds (cautiously) reassuring is its tentative judgment that widespread Zika transmission in the U.S. mainland is unlikely. If Zika turns out like dengue in the U.S., episodes of local transmission will likely occur but will likely then die out, mostly because we have better mosquito control and more protected indoor living standards than Latin America.

But even as officials at CDC and elsewhere voice this reassurance, they regularly add that there are no guarantees, that they might turn out wrong, and that they are being vigilant. And to add an additional margin of safety, more often than not they append advice about how to avoid mosquito bites.

CDC has two key domestic audiences with regard to Zika, and it is rightly saying radically different things to those two audiences.

Talking to Americans who are not at risk

The largest audience is people in the continental U.S. who have not traveled to countries where Zika is circulating widely and who have no plans to do so. For non-traveling Americans who are newly aware of Zika and very worried about it, CDC’s key messages are – and should be – mostly reassuring. The same factual messages are – and should be – mildly alarming for Americans who haven’t yet heard about Zika.

It is normal to become more worried than you need to be when you first find out about a scary new risk. Crisis communicators call this very common and very temporary response an “adjustment reaction.” It can sometimes be, and often appears to be, a brief overreaction. The key for risk communicators is not to ridicule the adjustment reaction – for example, not to accuse people of panic or hysteria or irrationality – but rather to guide the adjustment reaction, helping people put the new risk into perspective.

That typically takes weeks, not months or years. It takes longer if the authorities mislabel and mishandle the adjustment reaction than if they accept it as a normal, temporary, and even useful way for people to come to grips with a new risk that may require them to consider new precautions.

So far we think CDC is handling Americans’ adjustment reaction to Zika very well. CDC is doing a particularly good job at telling people what to expect and proclaiming uncertainty. Here is part of Dr. Anne Schuchat’s excellent introduction at CDC’s January 28 press briefing. Her words echoed the gold standard risk communication by Dr. Richard Besser at the start of the 2009 influenza pandemic.

Dr. Schuchat: It’s important to remember that this is a rapidly changing situation. As we get new information, we may need to update our advice. At this stage in a relatively new health threat, information evolves quickly, and we expect that the situation will continue to change as we learn more. We are working very closely with colleagues in the infected areas as well as at home to get the information we need, and as we learn about the virus and health effects, we will share what we know so you have the information you need to protect yourself and your family.

Here are what we take to be CDC’s five key messages about Zika. They are aimed at alerting – not alarming – one group; and aimed at reassuring – not over-reassuring – the other group.

1. Zika is not a public health crisis in the continental U.S., and we don’t expect it to become one. But it is a crisis for places where Zika is or will become widespread. And it is a crisis for potentially infected pregnant women, because the evidence is getting stronger that Zika virus can cause brain damage in fetuses.
2. So far, all the continental U.S. Zika cases are returning travelers infected elsewhere, but eventually there will probably be some local transmission.
3. We hope and expect that local transmission will not become widespread because the U.S. has better mosquito control and living conditions (screened windows, air conditioning) than most of Latin America. In the past, imported dengue cases have caused only small, brief local outbreaks.
4. We are not certain about this, since Zika has barely been studied, and has never been in the Americas before now. There are huge holes in what we know. We expect to learn surprising things, and will have to change our guidance as we learn.
5. It is important to support government mosquito control efforts, and to take individual precautions – especially pregnant women in places where Zika is circulating.

Some of these messages could be tweaked for greater effectiveness. When urging people to police their neighborhoods for mosquito breeding sites – standing water in containers and old tires, for example – CDC and other government sources should point out that mosquitoes don’t usually travel far. “The mosquitoes that bite you in your neighborhood,” CDC should explain, “are mostly your neighborhood’s mosquitoes, born and bred right in or near your back yard. So cleaning up standing water in your own neighborhood can reduce your local Zika risk.”

Most people we know do not realize this, and thus the advice to reduce mosquito breeding grounds around their homes can sound futile. For actionable advice to get acted on, people need to believe it will make a difference; that often requires an explicit explanation of why and how the recommended action will achieve meaningful change – not just an instruction to do it.

But on the whole we find CDC’s messaging for the overall U.S. population pretty impressive.

Talking to Americans who are at risk

The second audience is much smaller, but it is also more important as long as widespread domestic transmission does not occur: pregnant women who are considering travel to Zika-affected places or who have already traveled to such places and might have exposed their fetuses to Zika virus.

Since it was discovered in 1947, Zika has been considered a mild and thus unimportant mosquito-borne disease. The newly found link to birth defects changes that judgment radically.

CDC’s message to pregnant women and women trying to get pregnant who are considering travel to places with widespread Zika transmission boils down to this: Don’t go if you don’t have to go, at least till we learn more. If you have to go, try really hard not to get bitten by any mosquitoes while you’re there. If you have symptoms of Zika, get tested, even though the tests are not foolproof. Even if you don’t have symptoms, make sure your doctor does ultrasounds to check your fetus for microcephaly, even though ultrasounds can’t always identify microcephaly.

It’s a straightforward message, and no one could call it reassuring. It is a warning, justifiably anxiety-provoking.

(One target audience missing from the CDC’s advice is sexually active women who are not trying to get pregnant but who are at risk of getting pregnant anyhow. Advice about birth control for women contemplating travel to Zika-affected places has not been part of the messaging so far.)

What about pregnant women who have already traveled to Zika-affected countries and may have exposed their fetuses to Zika virus? We have one serious quarrel with CDC’s messaging to these women. It concerns CDC’s recommendations about which of them should be tested for possible Zika infection.

In prioritizing which pregnant women to test, CDC distinguishes between pregnant women with potential Zika exposure who have had symptoms of Zika infection and those who have not had such symptoms:

• CDC advises pregnant women with potential Zika exposure who have (or had) at least two symptoms of Zika infection, while traveling or shortly after returning, to be tested for current or past signs of infection.
• If the test is positive, CDC advises such women to seek the care of a doctor who specializes in problem pregnancies. (This is as close as CDC comes, and as close as it needs to come, to suggesting that pregnant women who test positive for Zika might choose to consider whether to have an abortion.)
• CDC says that pregnant women with potential Zika exposure but no history of symptoms should be followed by fetal ultrasounds to look for signs of microcephaly and/or brain calcifications. (Ultrasounds are also recommended for women who test negative for Zika infection.) If an ultrasound shows signs of fetal abnormalities, only then are these women advised to be tested for Zika infection.

Importantly, ultrasounds for microcephaly are most effective late in a woman’s pregnancy. The Zika antibody test, on the other hand, can be done early or late in the pregnancy. (Neither the blood testing of the mother nor the ultrasound testing of the fetus is perfect for ruling in or ruling out maternal infection or fetal abnormality.)

An estimated 75–80 percent of Zika infections are asymptomatic. So under CDC’s testing algorithm, 75–80 percent of pregnant women who actually were infected with Zika and whose fetuses are therefore vulnerable to microcephaly and possibly other birth defects are not recommended to get the Zika test. Instead, CDC recommends that they wait for their fetal ultrasounds.

But all potentially exposed pregnant women are in the same boat when it comes to deciding what action to take, regardless of whether they had symptoms of Zika or not. It makes obvious sense for every woman who was pregnant while or shortly after traveling in a Zika-affected country to want the test, even if she never had any Zika symptoms.

Why doesn’t CDC recommend that? In its guidelines for testing as of January 19, it states:

There is no commercially available test for Zika virus. Testing for Zika virus infection is performed at CDC and several state health departments. Health care providers should contact their state or local health department to facilitate testing and for assistance with interpreting results (4).”

To date there is very limited capacity for Zika infection testing, as CDC states elsewhere but not in the guidelines. In the guidelines, it just says:

Testing of asymptomatic pregnant women is not recommended in the absence of fetal microcephaly or intracranial calcifications.

It doesn’t say such testing is “not indicated” – that is, not medically justified. It just says it’s “not recommended.”

When CDC does think that testing is not indicated, it says so in the guidelines:

Testing is not indicated for women without a travel history to an area with Zika virus transmission.

It certainly seems like Zika testing for asymptomatic pregnant women with the relevant travel history would be medically indicated.

Eventually, the test capacity limitations are likely to be solved. (With luck, the specificity of the test results will also improve.) In the meantime, CDC probably reasons that a pregnant traveler who had symptoms is more likely to have been infected than a pregnant traveler who didn’t. So the best use of limited testing capacity is to recommend testing for women who traveled to Zika-affected countries and had some Zika symptoms while pregnant. That’s what CDC recommends.

Makes sense? Only if you’re not willing to think about – much less talk about – abortion.

Based on their personal values, some women in the U.S. consider abortion a viable option and some women don’t. So consider four women, all of whom may have had Zika infections while pregnant:

1.  Ashley

Ashley will carry her baby to term no matter what. She still wants a Zika test, and she wants ultrasounds when her pregnancy is far enough along, so she can better assess what she might be facing and prepare to deal with it if the tests are positive … or so she can feel less worried if the tests are negative.

But Ashley’s tests aren’t actionable. She is going to have her baby regardless of what she learns. Since Zika test capacity is limited, Ashley should be triaged to the back of the line – whether she had Zika symptoms or not.

2.  Brittany

Brittany will consider aborting her fetus only if an ultrasound shows clear evidence of serious birth defects (if it’s not too late). But just knowing that she probably had Zika infection wouldn’t be enough for her to think about abortion, especially since nobody knows what percentage of Zika pregnancies produce brain-damaged babies.

Brittany should be at the back of the line too, again whether or not she had symptoms.

3.  Courtney

Courtney will consider aborting her fetus if she has a positive Zika test. If she can’t get a test, she will wait for ultrasounds before deciding whether to carry her baby to term.

But for a bunch of reasons, Courtney would much rather make the decision now, based on a Zika test:

• Zika tests are uncertain, but ultrasounds are uncertain too. They sometimes miss microcephaly, or they mistakenly detect it, or the results are ambiguous.
• Late ultrasounds are more reliable than early ones, but by then abortion is more dangerous and emotionally tougher, and may be illegal.
• At best, ultrasounds can’t detect birth defects that show up only later in life – and nobody knows yet what additional birth defects Zika may cause.

So for Courtney, unlike Ashley and Brittany, a Zika test would be actionable. She belongs ahead of Ashley and Brittany in line. At the very least, a Courtney who had Zika symptoms should be prioritized ahead of an Ashley or a Brittany who had Zika symptoms, and an asymptomatic Courtney should be prioritized ahead of an asymptomatic Ashley or Brittany. We would go further; we’d prioritize an asymptomatic Courtney ahead of even a symptomatic Ashley or Brittany – because Courtney has a decision she intends to make depending on her Zika test result.

Because CDC doesn’t want to get into the abortion thicket, its testing algorithm leads an asymptomatic Courtney to postpone her abortion decision. She may end up having a microcephalic baby she would have aborted if only CDC had recommended that she get the test in time.

4.  Danielle

Danielle is determined to have an abortion if she has a positive Zika test. A negative test would persuade her not to abort, unless a later ultrasound revealed a problem.

But Danielle differs from Courtney in a key way: If Danielle can’t get the Zika test, she will abort her fetus now rather than wait to see if anything alarming shows up later on an ultrasound.

If Danielle never had Zika symptoms, the CDC algorithm says she shouldn’t get the test. For Danielle, that means she will get an abortion instead – an abortion she wouldn’t have wanted if she had been tested and the test result was negative.

We would certainly prioritize Danielle ahead of Ashley and Brittany for Zika testing, regardless of whether she had symptoms. We might well put her ahead of Courtney as well, since Courtney is more willing than Danielle to wait for ultrasounds before deciding about a possible abortion.

CDC has considerable experience with the ethical dilemmas of prioritizing scarce resources. Back when concern about H5N1 bird flu was at its height, we participated in one of a series of CDC-sponsored public meetings to ponder the right priorities for allocating scarce vaccine during a hypothetical H5N1 pandemic.

The problem of allocating access to Zika testing is not hypothetical. But to date CDC doesn’t seem to have pondered the problem very deeply. Or perhaps it has, and believes it simply cannot afford to give any advice that is hooked to women’s views on abortion.

All the above assumes that Ashley, Brittany, Courtney, and Danielle will follow CDC’s testing algorithm. We don’t know how mandatory or close-to-mandatory the algorithm actually is. Suppose a woman who may have had Zika infection while pregnant, but never had any Zika symptoms, asks her doctor to order the test anyway, even though CDC recommends testing only for pregnant travelers who showed some symptoms. Suppose her doctor agrees. Will the handful of labs authorized to do the Zika test be willing to do it on a woman who was never symptomatic? Or will they require the doctor to certify that she had symptoms?

We haven’t been able to find the answer to this question. Maybe the issue hasn’t arisen yet – but it surely will if the number of potentially affected pregnant women exceeds the testing capacity of the labs.

Or maybe asymptomatic women (or their doctors) will simply lie in order to get their tests.

In an ideal world – our ideal world, anyway – CDC would assert, publicly, that women who are considering abortion based on the results of a Zika test should go to the front of the testing line. But we understand how politically untenable it would be for CDC to say that. Perhaps CDC could consider saying simply that women should go to the front of the line if they articulate any decision they face that will depend on the results of the test. Then CDC wouldn’t be prioritizing only women considering abortion … but rather all women for whom the Zika test is actionable.

We have gone into such detail on the abortion issue for three reasons.

First, facing the possibility of a severely brain-damaged baby is heart-wrenching for any parent. Affected women for whom abortion is not an option deserve our sympathy and our support. But they don’t need a Zika test nearly as much as affected women for whom abortion is an option. CDC’s testing algorithm distorts the rational prioritization of limited Zika testing capacity.

And it does so for reasons that are basically about risk communication. Because CDC doesn’t want to mention abortion for understandable political reasons, it has no choice but to “mis-recommend” who should get Zika tests. The tragic result is that Courtney may give birth to a brain-damaged baby she would have aborted if she had had a positive test, while Danielle may abort a healthy fetus she would have carried to term if she had had a negative test.

(Again, we realize that none of these tests is perfect, whether blood/serum tests for Zika or ultrasounds for fetal malformation.)

Second, we are focusing on this risk communication deficiency because on the whole we think CDC is doing an excellent job of Zika risk communication – warning pregnant women considering trips to Zika-affected places, empathizing with pregnant women back from trips to Zika-affected places, cautiously and tentatively reassuring everyone else, advising on commonsense precautions, and insisting that everything about Zika is uncertain and subject to change.

Our third reason is that the abortion problem is representative of an important class of health risk communication deficiencies: deficiencies driven by taboos of various sorts, but hiding behind the façade of “evidence-based” (even “tentative evidence-based”) science. In the case of abortion, the taboo results from an understandable aversion to pushing career-threatening political hot buttons.

Another taboo is the reluctance of health officials to mention that an emerging public health crisis might – just might – justify reconsidering mosquito control methods that have been abandoned for environmental reasons, such as the powerful pesticide DDT. That probably makes little sense in the continental U.S., given that we have pretty good mosquito control already, that we don’t expect Zika to be widespread here, and that U.S. public opinion is highly skeptical about even much safer pesticides. But it might make sense in Latin America and elsewhere. We have no expertise and no opinion on that question.

The last taboo we will mention is the reluctance of officials to consider whether some women who want to have a baby but live where Zika exposure is high might be encouraged to try to contract Zika intentionally well before they start trying to get pregnant.

This possibility, too, is unlikely to make sense in the continental U.S., where domestic transmission is tentatively expected to be rare. But as long as a vaccine doesn’t exist, it might make sense in countries where Zika transmission is widespread and abortion is not an option – more sense than telling women without good access to birth control not to get pregnant. We realize there are several preconditions: a readily accessible, affordable, and reliable test; good evidence that Zika only rarely has serious health effects (like Guillain-Barré syndrome) in adults; etc. Again, we don’t have the expertise to assess whether this is an idea worth pursuing.

But our risk communication expertise tells us that there is a taboo against intentional infection in the minds of public health officials, a taboo nurtured in part by their long battle with the anti-vaccination movement. Try suggesting “Zika parties” to anyone in public health and see what sort of reaction you get. That tells us that even if the technical objections can be overcome, the public health profession is likely to resist even considering the possibility of intentionally infecting women with Zika before they start trying to have a child.

Copyright © 2016 by Peter M. Sandman and Jody Lanard

Contact information page:    Peter M. Sandman