Hearing Notes: U.S. Public Health Response to the Zika Virus - Continuing Challenges

On May 23, the U.S. House Committee on Energy and Commerce held a hearing to explore continuing challenges in the U.S. public health response to the Zika virus. Drs. Luciana Borio (Acting Chief Scientist, FDA), Rick A. Bright (Director, BARDA, HHS), Anthony Fauci (Director, NIAID), Timothy Persons (Chief Scientist, GAO), and Lyle Peterson (Director, Division of Vector-Borne Diseases, NCEZID, CDC) testified.

Common themes that emerged were the uncertainty of long-term impacts of Zika infection; the importance of steady, predictable funding for public health response, including mosquito control and diagnostic and vaccine development; and the need to conduct effective risk communication to at-risk populations.

Some highlights:

Zika epidemiology

  • Every state besides Alaska has reported a Zika case
  • 84 countries have evidence of vector-borne Zika cases

We still don’t know …

  • Actual number of infections
  • Enough about the long-term health impacts of Zika infection in men and children who are born to infected mothers
  • No good model for how virus will spread this year

Public health needs

  • A case definition and understanding of how the virus spreads
  • Development and use of diagnostic tools and new vaccines
  • Mosquito control 
  • Effective communication on all levels

Witnesses

Dr. Persons

  • Stressed need to figure out biological mechanisms and risk factors, and short-and  long-term outcomes
  • Identified two key epidemiological research challenges: insufficiency of data and lack of computer models to predict spread, and a lack of time and funding to conduct research 
  • Identified a key diagnostic manufacturer challenge: lack of samples and FDA communication
    • He noted that HHS has led the way in progress but many challenges still remain
    • He said officials must determine which tests are most effective

Dr. Petersen

  • Noted that it will be important to follow the development of microcephalic babies to understand long-term effects

Dr. Borio

  • Said that FDA’s central role in response to public health emergencies is to support the development and availability of diagnostic tests, vaccines, and therapeutics 
  • Added that FDA also helps to ensure a safe blood supply (preventing 400 infected donations to date), advance strategies for vector control, and protect the nation from fraudulent products
  • Noted that vaccine candidates progressing at rapidly expedited pace

Dr. Fauci

  • Said that NIAID is conducting research to develop countermeasures, including rapid, specific, low cost diagnostic tools
  • molecular, serological (detect immune response of someone already infected)
  • Referenced a study in Brazil on 10,000 pregnant women  
  • Reported that NIAID is currently investigating five candidate Zika vaccines, including (from Dr. Fauci’s written testimony):
    • A DNA vaccine developed by the NIAID Vaccine Research Center – phase 2a/2b trial began in March, 2017
    • A live-attenuated Zika vaccine – will enter Phase 1 trials in late 2017
    • A Zika purified inactivated vaccine (ZPIV), codeveloped by NIAID, BARDA and WRAIR – phase 1 trials began in November, 2016
    • A mRNA vaccine - will enter Phase 1 trials in late 2017
    • A Zika vaccine developed on the rVSV platform – in preclinical development

Dr. Bright

  • Reported that BARDA is currently supporting the development of four candidate Zika vaccines (from Dr. Bright’s written testimony):
    • Moderna’s mRNA-based Zika vaccine
    • Sanofi Pasteur - an extension of the BARDA/NIH/WRAIR collaboration described above
    • Takeda Pharmaceuticals
    • Instituto Butantan

How does this vaccine response compare to other infectious diseases?

  • Dr. Fauci: Zika is the fastest vaccine development we’ve ever had 
    • Three months between time we uncovered sequence to putting it in an animal

 Should we have an emergency fund for issues like this?

  • Dr. Fauci: Yes, because money is being moved from other areas like Ebola in order to work on other urgent issues like Zika
    • “This whole thing is a marathon. We have to have consistent support to be prepared for consecutive years.”  
  • Best possible scenario for vaccine: efficacy signal by mid-2018 for FDA evaluation
    • “While we have begun clinical testing of several Zika vaccine candidates, a safe, effective, and fully licensed Zika vaccine likely will not be available for several years."

Why does CDC think pace for emerging infectious diseases is accelerating?

  • Dr. Petersen: Growth of world population and mega cities, increases in travel and trade that bring viruses to every corner or earth very quickly, climate change 
  • He added that we need to increase efforts toward innovation and discovery: surveillance, mosquito control (sustained effort to rebuild infrastructure), and develop a more national and sustained approach toward vector-control

What are the roles contraceptives and preventive care measures play in combating Zika?

  • Dr. Petersen: Half of the pregnancies in the United States are unplanned, two-thirds in Puerto Rico are unplanned. Our job is to provide women with most accurate info possible so they can make their individual decisions alongside physicians
  • Dr. Fauci: lifetime care of microcephalic baby that survives costs millions of dollars

Why is strong public health infrastructure key to avoiding epidemics we see play out in other parts of the world?

  • Dr. Fauci: You can’t prevent an outbreak of a new infection. The trick is to prevent it from becoming an epidemic or pandemic
  • We have systems in place and the best public health agency in the world to track and control all threatening outbreaks  

How do we make predictive modeling to forecast future cases given that 80 percent of those infected do not have symptoms?

  • Dr. Persons: We have to take current models on sexually transmitted infections and vector-borne diseases. They’ve never been conjoined until now, so we have to come up with a new model that uses both. Consistent research is the only way to do this
  • Dr. Bright: BARDA’s scope does not currently include vector control. However, if enough data is collected to prove vector control significantly reduces infection, then there would a significant role of federal government in implementing vector control measures
  • Dr. Fauci: Work is being done to try to develop a universal flaviviruses vaccine using a common part of all flaviviruses  

$300 million has already been spent to develop vaccine. The Army is not guaranteeing a fair price. What if the vaccine is priced out of reach of many? 

  • Dr. Fauci: It’s important for it to be available to as many people as possible, but I am not sure we have the measures in place to make that happen  

More information on the hearing and witnesses is available at energycommerce.house.gov.

Zika: Where We Stand Now

The month of October has finally arrived, bringing to a close what has been one of the hottest summers on record on the East Coast. As Halloween and Thanksgiving draw nearer, so too does cooler fall weather, bringing with it a decline in U.S. mosquito populations. These mosquitoes, particularly those of the Aedes aegypti species, have caused widespread concern throughout the U.S. and abroad, as Zika virus infections have emerged in numerous countries. The continental United States saw its first locally transmitted Zika case in Florida in late July, and additional locally-acquired cases have been occurring since then.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), has been at the forefront of the U.S. fight against this disease. Last month, I had the pleasure of attending a colloquium at Georgetown University’s O’Neill Institute for National and Global Health Law led by Dr. Fauci, which also featured other experts in policy and infectious diseases including Dr. Stephen Morrison from the Center for Strategic and International Studies, and Dr. Daniel Lucey from the O’Neill Institute. While a wide variety of topics were addressed, there were two themes that continually emerged during their discussion.

1. Funding. Public health practitioners cannot effectively fight a disease that has been declared a public health emergency of international concern by the World Health Organization with an empty bank account. While awaiting funding from Congress, NIAID had to shift money earmarked for other deadly diseases such as malaria and Ebola, and the National Institutes of Health had to pull money from other areas to fund Zika activities and research, including vaccines, treatment and vector control.

On September 28, nearly eight months after President Obama’s initial request for $1.9 billion dollars in emergency supplemental appropriations to fight Zika, Congress finally passed a funding bill. While the funding bill, at $1.1 billion dollars, is 800 million dollars short of President Obama’s initial funding target, it is a move in the right direction. Now, it is critical that these funds are distributed promptly to aid in vector control, to invest in research to better understand the effects of the virus on fetuses and children, and to aid in diagnostic technologies and vaccine research.

The idea of a public health contingency fund was brought up multiple times by the panelists, and could potentially alleviate the need to grapple for funding as an epidemic is unfolding. This would greatly enhance preparedness for infectious disease threats, allowing medical countermeasure research to commence quicker and provide resources for public health departments who are in the throes of responding to an emergency.

2. Preparedness. Zika virus is not the first emerging infectious disease to challenge our national and global health security, nor will it be the last. Rapid urbanization, high-speed global travel, climate change and deforestation are just four of the many factors that are driving the emergence or reemergence of severe infectious diseases. Given this reality, we should not be surprised when they occur, and have robust plans and programs in place to mitigate their worst effects. This more proactive response prioritizes disease surveillance, rapid microbiological characterization, medical countermeasure development, and support to the local health sector. As Dr. Fauci stressed, infectious diseases know no borders, and epidemics outside of the U.S. should be just as concerning as ones within our own borders.

As cooler temperatures approach, it is likely that the number of Zika virus cases will decline. It is important, however, that the lessons learned from the Zika virus outbreak are applied to future infectious disease outbreaks, and we’re able to shift to a more proactive response when the next disease inevitably emerges.

Status Report: Zika Virus in the United States

As of early October, there have been 105 locally-acquired cases and 3,712 travel-associated cases in the United States, and thirteen cases of Guillain-Barre Syndrome (GBS). In the U.S. territories, there have been 24,118 locally acquired cases, and 83 travel-associated cases reported, with an unknown number transmitted through sexual contact. Additionally, there have been 39 cases of GBS in U.S. territories. Florida is the only state thus far to have reported locally acquired cases, and along with New York, also makes up the greatest percentage of travel-associated cases.  Puerto Rico, unfortunately, accounts for nearly all of both travel-associated and locally acquired cases in the U.S. territories, and is easily bearing the greatest burden from the Zika outbreak.

The National Institute for Allergy and Infectious Diseases NIAID is currently developing multiple vaccine candidates for Zika prevention. The candidates include a DNA-based vaccine, a live-attenuated vaccine, an investigational vaccine using genetically engineered vesicular stomatitis virus, and a whole-particle inactivated vaccine. In late September, the candidate DNA vaccine entered phase 1 clinical trials, which will determine its safety in human subjects. DNA vaccines are a relatively new immunization technology where a sequence that encodes an antigen of interest is introduced and expressed, hopefully leading to an immune response. The early progress of this and other Zika vaccine candidates is encouraging, however it will likely be years before a vaccine is available to the public.

Prevention has largely included efforts to control the mosquitoes that vector Zika, including aerial spraying of insecticides and getting rid of standing water. Individuals are also encouraged to protect themselves from mosquito bites by using insect repellent and wearing long-sleeve shirts. Since Zika is now known to spread through sexual contact, safe sex practices such as condom use are also being promoted.

Finally, in a recent publication in JAMA, Dr. Tom Frieden, the director of the CDC, provides a more in-depth update on the Zika outbreak, which he calls an “unprecedented emergency” due to its ability to cause birth defects via a mosquito bite.

The future of Zika virus is uncertain. While impending colder temperatures will almost certainly decrease transmission in most of the continental US, it remains a possibility that Zika will persist in over-wintering Aedes mosquitoes. As a result, continued research in medical countermeasure development should remain a priority. The U.S. public health and healthcare sectors should also continue to prepare to support the children and families who have been, and will continue to be, impacted by this virus. 

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: http://www.baltimoresun.com/news/opinion/oped/bs-ed-olympics-zika-20160605-story.html

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!

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.