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.