Thursday, June 30, 2005
I will discuss steps the Centers for Disease Control and Prevention (CDC) is taking as a member of this Task Force and with many other partners both domestically and globally. The strength and flexibility of CDC and other components of the public health system are vital assets as the U.S. sharpens its readiness for an influenza pandemic. Although we have made significant progress, more work is needed, particularly in the areas of surveillance capacity and response, and in the development of potential vaccines. Increased public awareness and understanding about infection control, community containment and travel, and other actions also are important in preparation for an influenza pandemic.
In discussing pandemic influenza, I want to emphasize that the issues of pandemic influenza and inter-pandemic influenza (so-called “annual influenza”) are inextricably linked. The same laboratories, the same health care providers, the same surveillance systems, and the same health department plans and personnel will guide both responses. Making sure that these people and organizations can address inter-pandemic influenza is our best overall hope for making sure the U.S. is prepared for an influenza pandemic.
Pandemics in Perspective
There are several important points about influenza and pandemic influenza.
The Current Avian H5N1 Influenza Situation in Asia
Although the present avian influenza H5N1 strain in Asia does not yet have the capability of sustained person-to-person transmission, at least 100 persons have been infected, largely by having some form of contact with infected poultry, primarily chickens. In addition, a limited number of persons have been infected by very close contact with another infected person, but this type of transmission has not led to sustained transmission or large outbreaks. As of June 17, 2005 the World Health Organization (WHO) had confirmed 107 cases of H5N1 influenza in humans since January 28, 2004, with a case fatality rate of 51 percent. The World Organization for Animal Health (OIE) confirmed, as of June 8, 2005, that H5N1 had been found in animals from nine Asian countries in 2004 and 2005, with especially large outbreaks among animals in Vietnam and Thailand. Millions of domestic birds have been culled in attempts to stop the spread of the virus among animal populations. In addition to poultry, infections among migratory birds may have also been found since 2002.
At this point, the H5N1 strain now appears to be endemic in poultry and other birds in a number of Asian countries. This situation poses a threat to humans because H5N1 from such sources can continue to infect people and because persistence of H5N1 in these populations provides the virus with chances to mutate or reassort its genes with genes from other viral strains and create H5N1 viruses that can transmit easily among people. Recent studies also have found that domesticated ducks can appear healthy but carry and shed the H5N1 strain, allowing the virus to spread invisibly to other species. H5N1 also has been shown to naturally infect mammals, which is a particular concern because this increases the potential for H5N1 viruses to reassort with other influenza strains that already have the ability to spread among humans and other mammals. Studies have documented H5N1 infections of pigs, tigers, and leopards in Asia.
To monitor H5N1 viruses for changes indicating an elevated threat for people, we must continue to strengthen and build effective in-country surveillance, which includes enhancing the training of laboratorians, epidemiologists, veterinarians, and other professionals, and promoting the comprehensive reporting that is essential to monitor H5N1 and other strains of highly pathogenic avian influenza.
Responding to a Pandemic
In the earliest pandemic stages, isolation precautions for persons who are ill and quarantine for persons exposed probably will be needed to try and limit the spread of pandemic influenza and to obtain as much time as possible for producing supplies of a pandemic vaccine. These control measures will require interventions such as the evaluation of ill travelers. Certain steps have been taken or will be taken to facilitate such efforts. On April 1, 2005, the President amended Executive Order 13295, adding influenza caused by novel or reemergent influenza viruses that are causing, or have the potential to cause, a pandemic to the list of quarantinable diseases. CDC will implement travel notices to minimize the potential for infection to rapidly spread. Recently, CDC expanded the number and capacity of its quarantine stations at major ports of entry into the U.S. As with any quarantine, such activities need to be undertaken judiciously to minimize adverse effects on civil liberties.
Vaccination is the best overall, long-term strategy to reduce disease from inter-pandemic influenza outbreaks and pandemics. Antiviral medications, which can be used to prevent influenza and in some instances to treat influenza, provide another line of defense. These types of measures, together with those such as isolation of ill persons and quarantine of healthy exposed persons, help form a comprehensive preparedness approach both to address inter-pandemic influenza and to lay the foundation for responding to pandemic influenza.
The outbreaks of avian influenza in Asia have highlighted several gaps in global disease surveillance that the U.S. must help address to improve our ability to prepare for an influenza pandemic. These limitations include (1) a lack of infrastructure in many countries for in-country surveillance networks; (2) the need for better training of laboratory, epidemiologic, and veterinary staff; and, (3) the resolution of longstanding obstacles to rapid and open sharing of surveillance information, specimens, and viruses among agriculture and human health authorities in affected countries and the international community.
In the past year, CDC and DHHS have made significant progress toward enhancing surveillance in Southeast Asia. However, this initiative needs to continue at both national and international levels if we are to sustain our progress, expand geographic coverage, and develop an adequate capacity to conduct effective surveillance. These efforts at building international as well as domestic surveillance are essential for detecting new influenza virus variants earlier and making informed vaccine decisions for inter-pandemic influenza. With the ever-present threat of the emergence of a new pandemic strain, we need to know what is happening in commercial poultry farms and the family backyard flocks of Southeast Asia, as well as elsewhere throughout the world.
Recently, Congress passed and the President signed an FY 2005 Emergency Supplemental Appropriations Act for Defense, the Global War on Terror, and Tsunami Relief, which included $25 million in international assistance funds to prevent and control the spread of avian influenza in Asia. These funds will support disease surveillance among humans, laboratories, and training on avian influenza laboratory and field techniques in Asia. They are being provided both to the region of Southeast Asia and to six specific nations where human and/or animal disease is greatest. Funding will support the planning and preparedness needed to enable each country to carry out a rapid response in a more organized manner. National long-term planning is also necessary for these countries; therefore they must also strategically apply to non-governmental organizations for additional funds to complete their preparedness efforts. Funds are also being provided for three countries, Cambodia, Laos, and Vietnam, to conduct active case detection of human disease, and additionally to Burma, China, and Indonesia for detection of animal disease. With respect to Burma, any avian flu assistance activities would be channeled through international non-governmental organizations or be conducted by international health organizations and not through the Burmese government. We will be happy to brief Congress on the specific activities that will involve Burma. Improved laboratories, including addressing biosafety for animal and human specimens will be the initial focus. Better in-country communications will be developed to assist these populations to taking steps to prevent infection and disease. Direct assistance to Vietnam will provide technical help for the safe development of an H5N1 vaccine. Finally, rapid response teams for Vietnam, Cambodia, and Laos will be organized and trained to respond to a crisis by identifying disease and instituting quarantine, isolation, and any other control measures that are necessary. These teams will be supplied with materials to be stockpiled in Southeast Asia, so that they will be equipped with proper personal protective equipment when they conduct case investigations.
On the domestic side, during the past year, CDC has considerably improved surveillance in this country by working with the Council for State and Territorial Epidemiologists (CSTE) to make pediatric deaths associated with laboratory confirmed influenza nationally notifiable, and by implementing hospital-based surveillance for influenza in children at selected sites. CDC will continue to work with CSTE to make all laboratory confirmed influenza hospitalizations notifiable. Since 2003, we have issued interim guidelines to states and hospitals for enhanced surveillance to identify potential H5N1 infections among travelers from affected countries, and these enhancements continue. CDC also has been holding special laboratory training courses to teach state laboratory staff how to use molecular techniques to detect avian influenza. CDC has trained professionals from all 48 states that desired training.
In addition, we are working to: (1) ensure that states have sufficient epidemiologic and laboratory capacity both to identify novel viruses throughout the year and to sustain surveillance during a pandemic; (2) improve reporting systems so that information needed to make public health decisions is available quickly; (3) enhance systems for identifying and reporting severe cases of influenza; (4) develop population-based surveillance among adults hospitalized with influenza; and, (5) enhance monitoring of resistance to current antiviral drugs, to guide policy for use of scarce antiviral drugs.
Managing the Vaccine Supply
In the U.S., public demand for influenza vaccine varies on a yearly basis, but having a steadily increasing demand would provide companies with a reliable, growing market that would be an incentive to increase production. In FY 2006, DHHS and CDC have provided $40 million in new funds for purchasing influenza vaccine for the pediatric stockpile to protect against annual outbreaks of influenza, and $30 million for contracts to expand the production of bulk single-strain influenza vaccine for use if needed during annual influenza seasons or possibly in a pandemic situation. In addition, the President is requesting $120 million in FY 2006, an increase of $21 million, to encourage greater production capacity that will enhance the U.S.-based vaccine manufacturing surge capacity to help prepare for a pandemic and further guard against annual shortages.
DHHS also appreciates the inclusion of $58 million in the FY 2005 Emergency Supplemental to procure additional influenza countermeasures for the CDC Strategic National Stockpile (SNS) in FY 2005. At present, the H5N1 viruses isolated from people in Asia during the past two years appear resistant to one class of antiviral drugs but sensitive to oseltamivir (Tamiflu). Accordingly, the SNS has stockpiled enough oseltamivir (Tamiflu) capsules to treat approximately 2.26 million adults and oseltamivir (Tamiflu) suspension to treat nearly 110,000 children. With the increased funding, CDC plans to purchase an additional 2 million regimens of oseltamivir. In addition, SNS funds have been used to purchase approximately 2 million bulk doses of unfinished, unfilled H5N1 vaccine. This vaccine has not yet been formulated into vials, nor is the vaccine licensed. Clinical testing to determine dosage and schedule for this vaccine began in April 2005 with funding from the National Institutes of Health. Additionally, DHHS also is supporting the development and testing of potential dose-sparing strategies that potentially could allow a given quantity of vaccine stock for use in more people.
One of the main efforts by CDC is to expand the nation’s use of influenza vaccine during inter-pandemic influenza seasons. This increase will help assure that the U.S. is better prepared for a pandemic. Influenza vaccine demand drives influenza vaccine supply. Therefore, if we can increase annual vaccination efforts, we will increase annual production efforts, which help strengthen our capacity for vaccine production during a pandemic. Discussions are under way to review the studies that would be needed to consider broadening recommendations for influenza vaccination. CDC also is developing strategies to increase influenza vaccine demand and access by persons who are currently recommended to receive vaccine each year. For example, according to a 2003 Institute of Medicine report, there are approximately 8.2 million uninsured adults 18-64 years with high-risk conditions warranting vaccination against influenza. If such persons receive influenza vaccine, it will help to increase annual demand for vaccine, because one of the best predictors of being vaccinated is having been vaccinated in a previous season. This increase in annual demand will lead to increased production capacity, and thereby increase vaccine supply both annually and during a pandemic.
Additionally, for planning purposes, CDC has identified influenza vaccine supply scenarios that may occur in future influenza seasons. These scenarios range from worst-case to best-case situations and are an important part of CDC planning efforts. We are preparing recommendations, plans, and communication messages for each of these possible situations.
Thank you for the opportunity to share this information with you. I am happy to answer any questions.
Last Revised: June 30, 2005