Remembering DA Henderson in Stories and Tributes

The world lost a great man today.  We have posted a summary of DA Henderson’s incredible life and achievements here, but that is only a glimpse into the story of his extraordinary life.  We wanted to use this blog post to invite others who knew him, worked with him, or met him along the way to share their stories, tributes, fond memories of DA as one way of honoring him and sharing what people found to be so special about him.  I will start. 

DA’s professional life is almost beyond description.  From the time he was a young doctor in public health, he was drawn to big problems and never stepped away from a challenge.  In the 1960s, he was expected to fail as newly named Director of the smallpox eradication program, but more than a decade later – with the help of more than a million people along the way – he succeeded.  Using the structures and programs built in that effort, DA became a global champion of the Expanded Program on Immunization, a childhood global immunization effort that has saved countless lives around the world.   He changed the way schools of public health approached their mission. He brought public health thinking into the highest halls of government for Presidents Bush and Clinton. He started talking about emerging infectious diseases and deliberate biological threats in ways that were important and courageous, and that galvanized a cadre around the country and the world to commit themselves to these issues.

It was his conviction and leadership that led me into working on health security and public health.  His calls to action, the clarity of his voice and reasoning, and his friendship all persuaded me to join him in this work and to help him start an organization focused on these issues 18 years ago.  As of the start of this summer, he continued to be an ongoing important presence and voice in our Center that helped shape all of our thinking.   

In the time that I was lucky enough to know him and work with him, I saw him provide his counsel to public health leaders around the world dealing with their crises of their day.  I saw him accept almost every invitation to teach that came his way.  I saw him wade into controversies without a moment’s hesitation when he believed something needed to be done or a course needed to be corrected. 

It wouldn’t be surprising if someone as accomplished as DA became too busy to deal with the next generation.  But DA was the opposite.  He sat down with any aspiring student or colleague considering a life in public health.  He was generous beyond belief with his time and his energies. 

DA had the constant support of his incredible wife Nana and his kids who he adored. They were all on a tremendous journey along with him.      

We will miss DA terribly.  We hope his principles and experience and his teaching will live on in some small ways in all of us, and we know his work and his thinking will influence the rising generation of public health leaders in the US and around the world

If you have stories to share, tributes to offer, specific memories to pass on, we’d like to collect them below in the Comment section of this blog.  We will share them with DA’s family and friends, and it will help all of us to hold on to a bit more of him.  Please feel free to add to the Comment section directly.  

Pitt CCM Grand Rounds: Biosecurity, Medicine, and National Security - A Guided Tour

On August 17, Dr. Amesh Adalja delivered the University of Pittsburgh’s Department of Critical Care Medicine’s grand rounds. During his “guided tour” of biosecurity, national security and medicine, he discussed various threats to public health, including bioweapons and emerging infectious diseases; and how the UPMC Center for Health Security is working to ensure communities are resilient should an epidemic or disaster arise. To concretize the type of projects the Center undertakes and illustrate its relevance to critical care medicine, he discussed how to best plan for a large number of patients experiencing acute respiratory distress syndrome (ARDS) in the context of an avian influenza pandemic.

This grand rounds was live-tweeted by the Department of Critical Care Medicine, and we’ve compiled these Tweets to provide readers with a quick overview of Dr. Adalja’s tour of this important facet of medicine and public health. 

Update: Video of Dr. Adalja's talk is now available.  

Don't cancel the Olympics because of Zika

This opinion, by Tara Kirk Sell, was first published in the Baltimore Sun on June 6th.

With the Zika outbreak in the Americas raging and the growth of scientific support about potential birth defects from maternal infection, some in public health have called for the 2016 Summer Olympics in Rio to be postponed or moved. As a fellow public health researcher and a pregnant Olympian swimmer and silver medalist at the 2004 Olympics in Athens, I have a close-up perspective on both sides of this issue and believe this opinion does not balance the risks appropriately.

Importantly, there simply isn't enough evidence at this point to support a large-scale, intrusive public health action that will devastate so many people. While Zika can cause severe outcomes in some, the vast majority of people who are infected will not experience symptoms. Newly emerging scientific evidence has shown clear connection between Zika and birth defects, but there are simple protective actions that can be taken to reduce the risk of infection. Often, decision makers justify extreme public health interventions "out of an abundance of caution" and a desire to remove all risk from a situation. But these arguments overlook any real consideration of the costs of taking these unwarranted actions, which are often high for those people who are affected by them.

Read More:

Public Perception of GM Mosquitoes in Florida

As we approach Memorial Day weekend, summer is just around the corner, as is mosquito season. There has been a lot of discussion about what that means for public health this year as the Zika virus spreads in South America and the Caribbean and infected travelers return to the US. Most experts agree that we will likely see at least some local mosquito-borne transmission of this virus in the States this summer because we’ve seen similar outbreaks of dengue and chikungunya in years past.

Yet despite early warning of Zika arrival and our recent experiences with mosquito-borne outbreaks, little additional investment has been made here to support mosquito control, and Congress is currently balking at providing emergency funding to support Zika preparedness and response. Actually, most mosquito control districts in the US have faced drastic budget cuts over time or have been de-funded completely within the past few decades. This had allowed mosquitoes to proliferate, relatively unchecked in temperate areas of the country. For instance, the Aedes aegypti and albopictus species of mosquitoes, which transmit Zika, dengue, chikungunya and Yellow Fever, have expanded their range geographically to cover much more of the US than was previously thought.

Now, with the specter of Zika approaching, and no vaccine or treatment likely to come for many months or years, mosquito control is our best and only available option to address this problem right away. Yet, mosquito control isn’t easy. Even in places like Florida and Hawaii, where investment is relatively robust, there are other barriers to reducing Aedes mosquito populations and preventing disease transmission. Eliminating breeding is difficult because the mosquitoes can breed in very small amounts of water and in hidden locations. In addition, mosquitoes are beginning to become resistant to some insecticides and larvicides, rendering these control measures less effective than ever before. In response to these difficulties, there are a number of approaches being considered and tested around the world including new insecticides, public awareness campaigns, and introduction of sterile (genetically modified) mosquitoes to outcompete and thus reduce mosquito populations.  

One genetically modified Aedes aegypti mosquito, created by Oxitec, is being considered by the FDA for a field trial in the Florida Keys. However, this effort has been delayed, primarily due to public resistance to releasing the mosquito. We were interested in learning more about how the residents of the Key West neighborhood think about this issue.

In order to find out more, our group fielded a survey to the affected neighborhood in Florida last summer (before Zika had raised its ugly head). The goal of our study was to get a better understanding about local knowledge, attitudes, and beliefs regarding GM mosquitoes, and to gain insight into more effective approaches to community engagement surrounding mosquito control and disease reduction efforts. Our results provide a pre-Zika baseline of community attitudes toward GM mosquitoes, that is, to the best of our knowledge, unique in the rapidly growing scientific literature on the Zika virus.  

What we found was that among residents who responded, there was indeed significant opposition to GM mosquito use. Reasons for this opposition included general concern about GM mosquitoes, but also specific worries that GM mosquitoes could pass on modified genes to other mosquitoes, people, or animals; that introduction of these mosquitoes could have unforeseen and potentially harmful effects on the ecosystem; and that use of GM mosquitoes could lead to introduction of other GM products into the community. Many of the concerns expressed by residents have been countered with data and information from Oxitec and the Florida Keys Mosquito Control District (FKMCD), but residents were still not convinced. It is clear that a sustained dialogue with the community regarding the safety and efficacy of GM mosquitoes needs to occur. If and when GM mosquitos are introduced, the community needs to understand and be comfortable with the potential benefits, risks, and uncertainties.

When we examined opposition to GM mosquitoes more closely, we also found that both women and people who had never had personal experience with a mosquito-borne disease like dengue, were significantly more likely to oppose GM mosquitoes, indicating that the perceived risks of GM mosquito use in those groups outweighed the perceived risks of mosquito-transmitted diseases.

Now that Zika is becoming a major issue of concern, we think that public perception and attitudes toward GM mosquito use may be changing. So, this study is also valuable in providing baseline information from which to evaluate any changes in attitudes. With concern about health effects from Zika widely publicized in the US, risk perception has increased, and residents may be more likely to accept GM mosquito use than they were last summer. For example, a recent nation-wide survey by Purdue University indicated that a majority of surveyed Americans support the use of GM mosquitoes to control Zika in the US.

Follow-up studies to understand how community engagement efforts can be better designed and how risk perception influences community acceptance of new interventions like GM mosquitoes are in the works!

Reforming the Biological and Toxin Weapons Convention’s S&T Review Process

Editor’s Note: This guest post to the Bifurcated Needle was written by Amanda Moodie. Ms. Moodie is a Research Analyst at the National Defense University’s Center for the Study of Weapons of Mass Destruction, and was selected as an Emerging Leader in Biosecurity Fellow in 2015.  

As diplomatic conferences go, Preparatory Committee meetings for the Review Conferences of the Biological and Toxin Weapons Convention (BWC/BTWC) are generally rather dull. At quinquennial Review Conferences, States Parties review the operation of the Convention; the Eighth Review Conference, to be held in Geneva from November 7th to the 25th, 2016, will allow States Parties to take into account any relevant scientific and technological developments and assess the state of implementation of the Convention. The Preparatory Committee meeting, or PrepCom, gives delegations the opportunity to discuss the organizational aspects of the Review Conference, such as the Conference presidency, the distribution of posts of Chairs and Vice-Chairs of the subsidiary bodies among the regional groups, and the draft Rules of Procedure. This year marks a departure from the usual procedure, in that two PrepCom meetings will be held; the second meeting, scheduled for August, will “provide an opportunity for States Parties to consider comprehensively all provisions of the Convention,” while the first PrepCom, which took place 26-27 April, would work on “general exchange of views and the organizational aspects of the Review Conference.” Most of the substantive discussion that can help build consensus and explore ideas, in other words, won’t take place until later in the year. As a result, the first PrepCom was largely unexciting to all but the most die-hard multilateral negotiation wonks.

One PrepCom development, however, did catch the attention of BWC-watchers. Since 2006, the Preparatory Committee has requested the BWC’s Implementation Support Unit (ISU) to prepare, among other documents, a background information paper on “new scientific and technological [S&T] developments relevant to the Convention, to be compiled from information submitted by States Parties as well as from information provided by relevant international organizations.” This year, States Parties suggested that the S&T paper, as well as a background information document on relevant developments since the last Review Conference in other international organizations, should be dropped from the list of requests. The public response from BWC experts from the NGO community was not overwhelmingly positive:

It’s understandable that BWC experts are concerned about the absence of an S&T paper as background material for the RevCon. In order to make sure that the Convention functions appropriately and continues to serve its purpose of banning the development and production of biological weapons, representatives of States Parties need to stay informed about potential scientific developments that might make it easier for anyone to acquire such weapons, or even alter our understanding of what such weapons might be. Not every State Party has the capacity to carry out such reviews itself, and the ISU’s background paper ensured that all delegations were on the same page with respect to S&T developments prior to the RevCon – at least in theory.

The stated reason for the elimination of the S&T paper was the burden it was placing on the ISU. Early in the PrepCom this year, States Parties had upped the burden on the organization by requesting it to prepare two new background information documents, in addition to the eight papers it’s prepared for RevCons in the past. Some of the requested papers are compilations based on information submitted by States Parties or on previous RevCons’ Final Documents, but others require the ISU to carry out original research. Moreover, even the compilations require time and effort from the ISU, which is severely understaffed and will also have other work to do in preparation for the Review Conference. The S&T papers produced at the last two RevCons were compiled from information submitted by States Parties and international organizations. However, several States Parties not only provided details to the ISU on relevant scientific developments, but also prepared their own working papers which repeated the same information. Additionally, many States Parties did not receive or read the ISU’s paper before the RevCon and therefore did not hear about key scientific and technological developments in advance, which made it difficult for them to take those developments into account when reviewing the Convention.

So the ISU, which already has far too much work, was supposed to complete a paper that duplicated effort already being put forth by many States Parties and that other delegations likely wouldn’t read in time to put it to use. For these reasons, the S&T paper “was not widely regarded as a useful tool” [1] and was dropped. This is not ultimately a bad thing. Nor does it necessarily mean that the BWC will fail to take S&T developments into account during the treaty review process. In fact, there is significant support among States Parties to reform the S&T review process and figure out a better way to provide input to the Review Conferences on significant developments. Doing S&T review in a diplomatic treaty context is very difficult. The biological sciences are evolving at an incredibly rapid pace, and it will be tough for the Convention to keep up, even if reviews are carried out more frequently than every five years. Plus, it’s hard to identify which topics are actually relevant for the Convention. Diplomats do not always have sufficient scientific background to understand certain scientific advances, much less to grasp their potential implications and identify what questions need to be asked about their impact on the BWC.

Yet despite – or because of – these challenges, most delegations seem to understand the importance of the S&T review issue, and their working papers and comments in the exchange of views portion at the PrepCom suggest that they are prepared to reform it and make it more effective. The elimination of the ISU’s paper may be a sign that this has already begun: States Parties have already started to take a critical look at the S&T review process and eliminate redundancies or extraneous steps, with a view toward making it more efficient.



1 - Richard Guthrie, “[27 April 2016] The Preparatory Committee concludes its first session,” BioWeapons Prevention Project, PrepCom Report 13 (1 May 2016).

Please Refrain…

You never meant to cause us any sorrow.



You never meant to cause us any pain.

You only wanted one time to raise awareness.

But when you think on speculation,

Pause, and please refrain.

Please refrain, please refrain…

Be First.  Be Right.  Be Credible.  It is advice so central to crisis communication that it graces the cover of the CDC Crisis & Emergency Risk Communication (CERC) manual.  These are the tried-and-true basics of emergency and crisis communication.  I have lost track of how many after action reports have lauded those who heeded that advice, and pilloried those who forgot.

And then Prince died.

In the days following Prince’s death, speculation ran wild that he may have died from influenza or some complication thereof—prompted by reports from Prince’s spokespeople that he was recently hospitalized for the flu.  Some of these were written by public health and medical professionals, experts in their respective fields.  These pieces were, in turn, referenced by dozens of news articles and fed into the broader discourse surrounding the artist’s untimely demise.  While Prince having the flu and passing away in short succession may have seemed, superficially, like the perfect opportunity to raise awareness of flu fatalities (and I certainly appreciate this desire), I am left questioning the impact on public opinion of public health now that his death may have been linked to prescription painkillers.

In all fairness, all of the articles that I read readily acknowledged that the cause of Prince’s death was unknown.  But when recognized experts volunteer their opinion, regardless of whether or not they acknowledge the uncertainty, it lends validity to the speculation.  My major concern is that this was an unforced error.  During the response to an actual public health incident, health authorities are responsible for communicating what is known as well as what unknown about a given scenario, and they may be forced to speculate in order to take appropriate actions.  This was not a public health incident.  This was a celebrity death that was leveraged into an opportunity to discuss public health.  None of this speculation was necessary.  I fear that by trying to raise awareness about the severity of influenza, the experts—on whom we rely for clear, accurate knowledge during emergencies—may have damaged their credibility in the eyes of the public.  I fear that this speculation may be viewed by the public as yet another case of public health simply overreacting.

Public health struggles under the best of circumstances to maintain the public’s attention and trust.  Under the worst of circumstances, the burden of too little information and the demand to act and speak quickly can quickly derail a response.

On occasion, a well-meaning but misinformed public demands the impossible of us.

But there’s no study disproving a link between vaccines and autism.

Sometimes we do get it wrong, and recovering from that can be an immense challenge.

Yeah, remember when you guys said any hospital could handle an Ebola case?

Sometimes even when we are technically or factually correct, public perception may still disagree.

Remember in 2009 when you guys said that H1N1 was going to be a pandemic?

And sometimes, the public only reads the headlines, not appreciating the context or nuances of a given issue.

Remember when you guys said there would be a million cases of Ebola?

Now, I am just imagining—and fearing—the next conversation.

Flu isn’t that bad.  Remember when you guys said Prince died from the flu?



Zika Virus and Maternal and Child Health: Not an Either / Or

On April 14th, The New York Times posed an important question concerning Zika – “Should they [federal health officials] advise American women to delay pregnancy in areas where the virus is circulating?” We bring this up because we asked the same question in March and on further reflection, have not reached the same conclusion as the New York Times.

To recap, last month, the Centers for Disease Control and Prevention (CDC) recognized Zika virus infection as a cause of microcephaly and other developmental complications in-utero. Though there are still many unknowns, this is the first time in history where an arbovirus appears to be causally linked to severe congenital anomalies and developmental disorders. Clearly, as this epidemic unfolds, women of child-bearing age who are pregnant, may become pregnant or would like to become pregnant and who live in countries where Zika is actively circulating bear the brunt of the risk. In Latin America and the Caribbean several governments have advised women to completely avoid conceiving for varying time periods. With the continued spread of the virus, and an increasing number of imported and sexually transmitted cases, the question now is: should the US be doing the same for women in areas which are at highest risk for Zika importation?

As a Zika vaccine is not expected to be developed in the near future, and US mosquito abatement programs will likely struggle to control Aedes aegypti populations to the point where expecting mothers can be 100% sure that they will not be bitten by an infected mosquito, avoiding pregnancy is the lone guarantee that you will not have a child with Zika-related birth defects. However, as of yet, there are no federal advisories recommending avoiding pregnancy specifically. The reason for this lack of guidance is presented in the Times as a dilemma in which health officials either controversially infringe on women’s rights to reproduce or allow these terrible birth defects to occur when more could have been done. Presenting the information in this way poses a false dichotomy.

If science says that waiting to conceive is in the best interest of the mother and infant, then the CDC and other relevant public health officials should make that (non-binding) recommendation and allow women to make decisions accordingly. We should be providing complete information and possible options so that women can make the best-informed decision with their partner and healthcare provider. Doing so empowers women to make the best decision possible for themselves and their families.

We think it would be most helpful if federal health officials provided clear information, including risks and reasoning, for all affected demographics. What follows are some notional guidance for different risk groups in the United States:   

Women who want to or who are trying to become pregnant

In places where we see active transmission, it can be hard to avoid mosquito bites entirely, thus there will be some risk to the fetus if a woman becomes pregnant and is then infected. The only real way to completely avoid this risk is not to become pregnant during an outbreak or when you or your partner has been infected. Women and their partners should be advised to weigh these risks, with their doctor, when deciding whether to conceive during a time and in a place where disease exists. Public health professionals should provide their best current estimates of the risks of getting infected and the risk of the fetus being affected if the mother has the virus to inform these decisions. Additionally, they should provide information regarding the risks of using insecticides containing DEET and how those risks compare to those from Zika.

Pregnant Women

Women who are pregnant in an area with active Zika transmission should be provided with information about preventive measures, including:  

  • Limiting time outdoors
  • Keeping their homes free of mosquitoes
  • Eliminating breeding sites
  • Using bug repellant (correctly and effectively)-
  • Wearing protective and/or treated clothing
  • Using a condom the correct way every time
  • Avoiding sexual contact that might increase the risk of getting Zika infection.

For women who become infected, the importance of close coordination and communication with their doctors in order to monitor the health of the fetus should be emphasized. Early recognition and close monitoring will provide women with the best information and of the most choices about their pregnancy.

Parents of young children and babies

There is some question as to whether and to what extent Zika infection can impact newborns, infants and toddlers. Until we know more, there should be advice about how to protect babies and children from being exposed, including advice about breast feeding, insect repellent, protective clothing, and limiting time outdoors.

All women and men

All US citizens should understand all of the measures they can take to avoid getting the virus. This includes limiting time outdoors, keeping their homes free of the mosquitoes, eliminating breeding sites, using bug repellent (correctly and effectively), and wearing protective and/or treated clothing, using a condom the correct way every time, and avoiding risky sexual behaviors.

As we learn more about Zika and its connection to fetal birth defects, the guidance issued by CDC and other public health authorities will continue to be refined. Conveying uncertainties about the risks, and the need for constant reassessment of the situation in the US should also be highlighted in all communication materials. Until we know more about what the risks are and about specific measures that will limit those risks, the best thing for public health officials to do is present all of the relevant information and allow people to make their decisions accordingly. 

Our Approach to Financing Epidemic Response is Broken

Earlier this week, the AP reported that the Obama administration has agreed to re-purpose roughly $589 million of the $5.5 billion that was originally appropriated to combat the Ebola virus epidemic for the response to Zika. The administration had proposed a Zika-specific appropriation of $1.9 billion in February, but encountered resistance from Congress, who were of the opinion that “left over” funds from Ebola could be applied to this most recent infectious disease emergency.

The bulk of the reprogrammed funds had been committed to supporting the Global Health Security Agenda (GHSA), whose reason for being is to help support international capacity to detect and respond to new epidemics before they cross borders, and threaten global health. Nearly all nations are obligated via the 2005 International Health Regulations to develop these programs, but by and large don’t have the necessary resources to meet those commitments. GSHA was established, in part, to mobilize support for establishing and maintaining those surveillance and response systems. We hope those programs will receive funding commensurate with their importance, as has been suggested by the White House and members of Congress.   

The referenced $589 million also appears to take funds out of domestic preparedness programs, as the New York Times noted:

In addition to funds moved from the Ebola budget, an additional $79 million would come from several other accounts, including money previously allotted to the national strategic stockpile of vaccines and other emergency supplies for epidemics, said Sylvia Mathews Burwell, the secretary of the Department of Health and Human Services.

So in effect, what we’ve done is take from prevention and preparedness to fund Zika response.

Now, I recognize that resource allocation decisions are inherently political. The two month-long back and forth between Congress and the White House represents a fundamental reordering of perceived threats and priorities, such that the present threat of Zika, particularly to expectant mothers in Puerto Rico and the Gulf Coast, now trumps the threat posed by the Ebola virus (put aside, for a moment, the fact that that disease has flared back up). Make no mistake - Zika represents a clear danger, and HHS and others are poised to respond. But to do the job right, funds over and above their routine operating budgets are needed. 

We have to face up to an uncomfortable reality: the way we finance responses to severe infectious diseases like Ebola and Zika is fundamentally flawed. This problem isn’t unique to the US government either. Governments around the world as well as international organizations have struggled to respond promptly in the face of new infectious disease threats. SARS, H1N1 influenza, MERS, Ebola, and now Zika have all emerged, and all caught us flat footed. In the global health arena, the WHO has recognized the importance of dedicated funding for epidemic response, and has included financing in their post-Ebola reform measures. If enacted, such a contingency fund would enable a more nimble organizational response to outbreaks and disasters.

In the federal budget, such rainy-day funds are a rarity, due in part to the practice of budgetary raiding and a desire on the part of appropriators to maintain control over the purse strings. Rare, but not non-existent. FEMA’s Disaster Relief Fund is one example of “no year” money. In general, this mechanism allows for FEMA to provide funding for emergencies without having to wait for an event-specific appropriation, and is replenished periodically by the Congress. No such mechanism exists for epidemic response. In my view, it may be time to consider establishing such a fund within the HHS budget, so that the business of epidemic response isn’t contingent on the waging and deciding of political battles going forward.  

A “Bird’s Eye View” of the Zika Action Plan Summit

This past Friday, on April 1, 2016, the CDC hosted a Zika Action Plan Summit at its headquarters in Atlanta, Georgia. With representation from tribal, local, and state officials among other stakeholders in public health, speakers and panelists worked to equip officials with the tools to address the Zika outbreak, update the public on the latest Zika virus information, and create an opportunity for collaboration and discussion.

As the day progressed some clear themes arose. Speakers emphasized the importance of sustainable mosquito control programs, requiring greater collaboration between diverse groups at the local and state level who do not normally interact. Also, the need for significant federal emergency response funding was brought up numerous times. Participants and speakers alike highlighted the importance funding for research and ensuring access to the maternal health resources.

The event, with the hashtag #ZikaSummit, became a trending Twitter topic in the US on Friday as over 300 attendees participated in Atlanta, and 2,500 viewers tuned in remotely. For a unique perspective on the summit, we’ve compiled a series of tweets by participants and observers. 

Outstanding Questions: Zika’s Impact on Maternal and Child Health

The emerging Zika virus poses some unique challenges to patients, doctors, and public health practitioners that aren’t generally a focal point of emergency response efforts. The link to congenital birth defects – including, but not limited to, microcephaly – and Guillain-Barre Syndrome has generated a great deal of concern. As of March 7th, 2016 the CDC has identified 37 countries, mostly in Latin America and the Caribbean, which have active Zika virus transmission. The numbers of reported cases continues to climb as the arbovirus spreads to new locations.

Concerned about the implications for expectant mothers and their unborn children, the World Health Organization (WHO) declared the Zika virus and its yet-to-be-proven association with severe birth defects a Public Health Emergency of International Concern (PHEIC) on February 1st. As a result, basic research, public education, and public health surveillance of the virus has increased dramatically.  Government agencies and organizations all over the world have released guidelines for expectant mothers, travelers, laboratory workers, and clinicians. In the US, the CDC has advised that expectant mothers not travel to effected countries, and that men who may have been exposed to the virus use appropriate protection to avoid sexual transmission. For women living in effected nations, there is an unavoidable risk for infection which cannot be minimized by travel recommendations. To lower the risk for Zika-related fetal development complications, local governments have gone so far as to advise delaying pregnancy. Here are some examples:

  • Brazil’s Ministry of Health (MOH) advised women in the northeastern region of the country, where the Zika virus is most prevalent, to delay pregnancy.
  • Columbia, with the second highest incidence of Zika virus infection, has advised waiting eight months to get pregnant.
  • El Salvador’s MOH suggested the biggest delay on conception, advising deferred pregnancy for two years, until 2018.
  • Jamaica’s MOH has recommended that women delay their pregnancies for the upcoming six to twelve months.
  • Ecuador has recommended delayed pregnancy, but has not specified a timeline.

The unprecedented nature of these recommendations, and their temporal variability (ranging from 6-24 months), indicates that there’s still a significant amount we do not yet understand about the impact of Zika virus infection on mothers and their unborn children.

On February 29th, the Institute of Medicine released their Workshop brief outlining some of the potential research priorities for Zika going forward, including priorities related to understanding more about Zika and pregnancy. As part of the workshop, Dr. Sonja Rasmussen, an expert on pregnancy and birth defects related to infectious diseases, and a member of the Zika response team at CDC, provided a list of outstanding questions related to Zika and pregnancy, including:

  • How often does transmission of Zika virus from mother to fetus occur (what percentage of cases of infected pregnant mothers)?
  • How often does fetal infection result in congenital defects?
  • What other defects are related to congenital Zika infection?
  • What is the best way to diagnose Zika related problems in utero?

Researchers are beginning to work on finding answers to those important questions, but in the meantime, we also need to determine what protective actions women can take now.

The answer to this question will likely differ depending on the population and geographic location. In South and Central America and the Caribbean, where Zika is expected to spread rapidly, experts hope that herd immunity, which can be protective for more vulnerable populations, will develop quickly. In these areas with widespread disease, it is also the hope that women who are infected before pregnancy will develop immunity that will be protective in later pregnancies.

Given these epidemiologic assumptions for areas with widespread disease, public health recommendations for women to delay pregnancy for some period of time may make sense biologically. However, it is important that we continue to gather data about the incidence and prevalence of disease in countries where Zika is widespread to have an idea of how long women should delay pregnancy. In addition, it will be essential to understand more about immunity, whether initial infection really does confer immunity against future infection and if so, how long that immunity lasts.

That being said, recommendations to delay pregnancy for extended periods of time must be considered in the context of other important factors. Many Latin American nations do not have sufficient sexual education or affordable birth control options to adequately support the new demand that Zika has caused. This problem is compounded by the ongoing occurrence of sexual assault and deep cultural ties to Catholicism, which traditionally prohibits the use of birth control. Without readily available and affordable contraceptives, more women are expected to turn to unsafe and illegal abortions. New campaigns for extended access to medically attended abortions in Latin American nations have quickly arisen as more cases of microcephaly appear. Additional investment in public health education, family planning resources, and pre-natal care will be absolutely necessary.

In the US, Zika will likely not be as widespread as it is in the Caribbean, Central and South America. Sporadic local outbreaks are likely to occur, particularly in the southern US, where temperature is favorable and Aedes aegypti mosquitoes are plentiful, but outbreaks will probably not reach the point where herd immunity is achieved. In addition, most women in the US will not be exposed before they are pregnant and thus won’t have the same immunologic protection as women in endemic areas.

So, in the US, carefully crafted and targeted recommendations about pregnancy will be necessary. In the event that limited transmission of Zika does occurs in the US, it is conceivable that women of child bearing age in effected regions may be advised to avoid pregnancy until transmission is interrupted. Alternatively, CDC could opt to leave the decision up to the mother, her partner, and their healthcare provider while continuing to provide guidance and information. In addition, continued refinement of guidance regarding sexual transmission is crucial. Giving couples some idea of how long after infection that sexual transmission can occur will be necessary in order to improve compliance with recommended protective measures.

For the time being, public health messaging and reinvigorated mosquito control efforts are the best tools to prevent Zika infection. Public health officials will need to be careful and thoughtful about these recommendations, and mindful of second order impacts when telling women to delay pregnancy. But, with the information we have now, it seems that these recommendations are not unwarranted or overly cautious.