Emerging Infectious Diseases: Actions Needed to Address the Challenges of Responding to Zika Virus Disease Outbreaks
Highlights
What GAO Found
Since Zika virus disease was a newly emerging disease threat in the United States, and relatively little was known about the Zika virus prior to the 2016 U.S. outbreak, the Centers for Disease Control and Prevention (CDC), and the states were not fully equipped with needed information and resources at the beginning of the outbreak. This presented several challenges for Zika virus disease surveillance and research efforts, such as challenges related to establishing a national definition for reporting cases. Knowledge about Zika virus epidemiology has increased in the past year, including information about Zika virus disease incidence and distribution of cases, and its associated adverse health outcomes. Most of the 5,197 Zika virus disease cases reported by April 5, 2017 in the United States were associated with travel from affected areas outside the continental United States. Only two states had disease cases of local, mosquito-borne transmission—216 were in Florida and 6 in Texas. While much has been learned about the epidemiology of the Zika virus, many unknowns remain, including the actual number of infections and the full spectrum of outcomes.
The 16 Zika virus diagnostic tests authorized during the outbreak varied in their performance and operational characteristics. For example, they varied in their ability to detect the virus and provide accurate results. In developing the diagnostic tests, manufacturers faced challenges in several areas, including access to clinical samples and other authorized diagnostic tests for comparison purposes. Users of the tests also encountered challenges, including determining the most accurate test to use, and obtaining equipment needed to conduct the tests. Some manufacturers raised concerns about the difficulty in developing diagnostic tests that met the Food and Drug Administration's (FDA) requirements for Emergency Use Authorization and some users expressed concerns about selecting tests amongst those authorized. GAO also determined that CDC and FDA did not follow some of their guidance in communicating with users of diagnostic tests, including providing clear information that would have enabled users to more easily compare performance across different tests.
Mosquito control programs in the United States are implemented at state and local levels and are critical to mitigating the risks associated with the Zika virus. Control methods include applying pesticides, reducing available water sources for breeding, and using personal protection. Each method has its strengths and limitations. For example, some control methods are more effective at reducing mosquito populations while others help prevent individuals from mosquito bites. Similarly, each method has some limitations, for example, there is varied public opposition to the use of certain pesticides. CDC supports state and local mosquito control activities primarily by providing guidance on mosquito control methods and funding to support certain mosquito control efforts. Challenges federal agencies faced in supporting these activities include sustaining staff expertise in mosquito control during periods when there are no outbreaks, funding constraints, and effectively communicating information about the geographical distribution of mosquitoes that transmit the Zika virus.
Why GAO Did This Study
Zika virus disease can cause adverse pregnancy and neurological outcomes. Given this ongoing threat, GAO was asked to evaluate progress made and challenges faced by federal agencies in responding to the Zika virus outbreak in the United States.
GAO examined (1) information on what is known and not known about the epidemiology of the Zika virus, and any challenges with conducting surveillance and epidemiological studies, (2) characteristics of different diagnostic tests authorized during the outbreak, challenges test manufacturers and users faced, and the extent to which FDA and CDC followed their own communication guidance, and (3) the strengths and limitations of available mosquito control methods, and challenges federal agencies face supporting these efforts.
GAO reviewed literature and agency documentation, and interviewed federal and state officials about the Zika virus and the U.S. response. GAO also convened an expert meeting with the assistance of the National Academy of Sciences to discuss various issues surrounding the response to the Zika virus.
Recommendations
GAO is making five recommendations to FDA and CDC, including that CDC establish a transparent process for providing test manufacturers access to diagnostic tests and FDA and CDC provide information to help ensure that users of diagnostic tests can compare performance. Agencies agreed with four recommendations but raised some concerns with the fifth. GAO has addressed these concerns in the report.
Recommendations for Executive Action
| Agency Affected | Recommendation | Status |
|---|---|---|
| Department of Health and Human Services | The Secretary of Health and Human Services should direct the Commissioner of the Food and Drug Administration to consolidate information from individual diagnostic test labels and make this information available in a form that enables users to more readily compare information across tests. |
In August 2020, officials from the Food and Drug Administration told us they have completed consolidation of information for Zika virus diagnostic tests that have emergency use authorization. FDA posted this consolidated information in two files on their website.
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| Department of Health and Human Services | The Secretary of Health and Human Services should direct the Commissioner of the Food and Drug Administration to require manufacturers to list the identity of comparator assays on their diagnostic test labels. |
In August 2017, officials from the Department of Health and Human Services told us that the Food and Drug Administration planned to recommend to sponsors of Zika virus diagnostic tests that they provide a description of the comparator assay. As of February, 2024, FDA officials provided documentation demonstrating that for the 14 current ZIka diagnostic test emergency use authorizations, all now contain comparator assay information, which can consist of the name of the comparator assay, its relevant performance characteristics, or a reference to a publication outlining the comparator method. This meets the intent of the recommendation.
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| Department of Health and Human Services | The Secretary of Health and Human Services should direct the Director of Centers for Disease Control and Prevention to establish a transparent process to provide CDC diagnostic tests, upon request, to manufacturers that are in the final stages of diagnostic test authorization. |
In August 2017, officials from the Department of Health and Human Services told us that the Centers for Disease Control and Prevention (CDC) Technology Transfer Office is working to establish a transparent process that ensures CDC diagnostic tests can be provided to manufacturers. In April 2018, CDC finalized a Memorandum of Understanding that formalizes the process to assist in the rapid scale up of diagnostic testing through partnerships with the reference laboratory community.
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| Department of Health and Human Services | The Secretary of Health and Human Services should direct the Director of Centers for Disease Control and Prevention to include information on CDC-developed tests distributed to or shared with public health laboratories on CDC's website, including laboratory developed tests. |
In August 2017, officials from the Department of Health and Human Services told us the Centers for Disease Control and Prevention (CDC) provides information on CDC-developed diagnostic tests on the Food and Drug Administration's (FDA) website. We confirmed that CDC has updated its website to feature a direct link to FDA information on CDC-developed tests. In July 2018, CDC officials told us that CDC has identified internal subject matter experts and is establishing a joint working group with American Public Health Laboratories to create standardization of laboratory practices and enhance communication with state and local partners. In April, 2019, CDC officials told us they had established the Working Group and provided a copy of their signed charter. The mission of this Working Group is to create a standardized approach to the deployment of assays to laboratories external to CDC. This working group will facilitate coordination and help identify critical aspects of assay design and implementation needing improvement.
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| Department of Health and Human Services | The Secretary of Health and Human Services should direct the Director of Centers for Disease Control and Prevention to provide details such as collection records, dates, and data limitations on posted and disseminated mosquito distribution maps to better inform mosquito control experts and the general public. |
In June 2016, the Centers for Disease Control and Prevention (CDC) published a report on the distribution of the mosquitos that can transmit Zika virus and other viruses in the United States. This report included new county collection records, collection dates, and summary maps for each species of mosquitos. In August 2017, officials from the Department of Health and Human Services told us the CDC is planning to update the mosquito distribution information on their website by the end of 2017, and it will include the underlying model predictions and country collection records. In September 2017, CDC updated their website maps with additional information, including a reference to their model prediction article and additional details which can help inform users of the maps.
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