Thursday, November 17, 2005
The Department of Health and Human Services (HHS) Secretary Mike Leavitt has made influenza pandemic planning and preparedness a top priority. The Centers for Disease Control and Prevention (CDC) and other agencies within HHS are working together formally through the Influenza Preparedness Task Force that Secretary Leavitt has chartered to prepare the United States for this potential threat to the health of our nation. We are also working with other federal, state local and international organizations to ensure close collaboration.
As you are aware, the potential for a human influenza pandemic is a current public health concern with an immense potential impact. Inter-pandemic (seasonal) influenza causes an average of 36,000 deaths each year in the United States, mostly among the elderly and nearly 200,000 hospitalizations. In contrast, scientists cannot predict the severity and impact of an influenza pandemic, whether from the H5N1 virus currently circulating in Asia and Europe, or the emergence of another influenza virus of pandemic potential. However, modeling studies suggest that, in the absence of any control measures, a “medium-level” pandemic in which 15 percent to 35 percent of the U.S. population develops influenza could result in 89,000 to 207,000 deaths, between 314,000 and 734,000 hospitalizations, 18 to 42 million outpatient visits, and another 20 to 47 million sick people. The associated economic impact in our country alone could range between $71.3 and $166.5 billion. A more severe pandemic, as happened in 1918, could have a much greater impact.
There are several important points to note about an influenza pandemic:
The Current Status of H5N1 Virus In Asia
Almost all cases of H5N1 human infection appear to have resulted from some form of direct or close contact with infected poultry, primarily chickens. In addition, a few persons may have been infected through very close contact with another infected person, but this type of transmission has not led to sustained transmission. For an influenza virus to cause a pandemic, it must: (1) be a virus to which there is little or no pre-existing immunity in the human population; (2) be able to cause illness in humans; and, (3) have the ability for sustained transmission from person to person. So far, the H5N1 virus circulating in Asia meets the first two criteria but has not yet shown the capability for sustained transmission from person to person.
The avian influenza A (H5N1) epizootic (or animal) outbreak in Asia that is now beginning to spread into Europe is not expected to diminish significantly in the short term. It is likely that H5N1 infection among birds has become endemic in Asia and that human infections resulting from direct contact with infected poultry will continue to occur. So far, scientists have found no evidence for genetic reassortment has been found. Reassortment can occur when the genetic code for high virulence in an H5N1 strain combines with the genetic code of another influenza virus strain which results in easy transmission. However, the animal outbreak continues to pose an important public health threat, because there is little preexisting natural immunity to H5N1 infection in the human population.
HHS Role In International Preparedness
The Secretary’s and my trip reaffirmed the value of several actions undertaken by HHS and its agencies over the last few years. It is vital to monitor H5N1 viruses for changes that indicate an elevated threat for humans, and we are continuing to strengthen and build effective in-country surveillance, which includes enhancing the training of laboratorians, epidemiologists, veterinarians, and other professionals, as well as promoting the comprehensive reporting that is essential for monitoring H5N1 and other strains of highly pathogenic avian influenza. In collaboration with international partners, HHS is also pursuing a strategy of active, aggressive international detection; investigation capacity; international containment; and laboratory detection support. In the past year, working with the WHO and other international partners, HHS and its agencies has 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 conduct effective surveillance. These efforts to build international and domestic surveillance are essential for detecting new influenza virus variants earlier and for making informed vaccine decisions about inter-pandemic influenza. With the ever-present threat of a newly emerging strain that could spark a human pandemic, we need to know what is happening in commercial poultry farms and the family backyard flocks found in Southeast Asia, as well as migrating birds and animal populations elsewhere throughout the world.
Earlier this year, Congress passed and the President signed the Fiscal Year 2005 Emergency Supplemental Appropriations Act for Defense, the Global War on Terror, and Tsunami Relief. This legislation includes $25 million in international assistance funds for HHS, the U.S. Department of Agriculture (USDA) and the United States Agency for International Development (USAID) to prevent and control the spread of avian influenza in Asia. With these funds, HHS and its agencies are working to assist in developing regional capacity in Southeast Asia for epidemiology and laboratory management of pandemic influenza. Strategies include developing and implementing an avian influenza curriculum for epidemiologists and laboratorians, training for public health leaders to develop a national network of public health field staff, and training for local allied health personnel to detect and report human cases of influenza. HHS staff are being assigned to Vietnam, Cambodia, and Laos to facilitate improvements in the detection of influenza cases and to provide technical assistance in investigating cases as well as in developing national preparedness plans by the Ministries of Health, with the assistance of WHO and other partners.
We are also working with the USAID, WHO Secretariat, its Regional Offices and Ministries of Health in these countries to increase public awareness about the human health risks associated with pandemic influenza, and to advise countries concerning prevention or mitigation measures that can be used in the event a pandemic occurs.
HHS through CDC is vigorously working to increase laboratory capacity in the region and to provide laboratory support for outbreak investigations, including: testing clinical samples and influenza isolates; diagnosing the presence of avian influenza in humans by supplying necessary test reagents to the region and globally; and, developing vaccine seed stock to produce and test pandemic vaccine candidates. The HHS National Institutes of Health (NIH) and Office of Public Health Emergency Preparedness are also providing technical assistance to the Government of Vietnam as it proceeds with the development of a human H5N1 vaccine, including support for clinical trials CDC is one of four WHO Global Influenza Collaborating Centers. In this capacity, CDC conducts routine worldwide monitoring of influenza viruses and provides ongoing support for the global WHO surveillance network, laboratory testing, training, and other actions. HHS also supports the WHO Headquarters in Geneva and the WHO Regional Offices in Manila and New Delhi for pandemic planning, expansion of global influenza surveillance, shipment of specimens, training, and enhancing communications with agricultural authorities. Several of the top flu specialists on the WHO staff are HHS personnel on loan, another demonstration of our strong commitment to international collaboration in the fight against the threat of a pandemic influenza.
In addition to our partnership with USAID under the Tsunami supplemental appropriation, HHS also partners with other U.S. Government departments in its international collaboration such as with the Department of Defense Naval Medical Research Unit Two (NAMRU2) in Indonesia and Naval Medical Research Unit Three in Cairo (NAMRU3). These collaborations support training, the expansion of influenza surveillance networks to countries where none exists, the enhancement of the quality of surveillance in other countries to enhance outbreak detection, seroprevalence studies in populations at risk for avian influenza such as poultry workers, and enhanced outbreak response.
Wild Birds, Poultry, and Other Animals: Implications For Agriculture
The current poultry outbreaks of highly pathogenic avian influenza A (H5N1), which began in Southeast Asia in mid-2003, are the largest and most severe on record. Many countries have been affected simultaneously, and the loss of millions of birds has resulted in serious economic disruptions. The causative agent, the H5N1 virus, has proven to be especially tenacious. Despite the death or destruction of an estimated 150 million birds, the virus is now considered endemic in many parts of Southeast Asia, and control of the disease in poultry is expected to take years.
In the United States, USDA and the Department of the Interior coordinate most work on avian influenza viruses among birds and other animals. CDC collaborates with USDA and the Department of the Interior in critical partnerships for domestic preparedness for a possible avian influenza outbreak in the United States. CDC relies on USDA for domestic and wild bird, backyard bird, live bird market and poultry products surveillance as a way to detect threats to human health early on. Early detection will allow the US Government to have the most up-to-date and reliable information which will help to save human lives. CDC and USDA are also working together now to develop a plan for the prompt notification and coordinated interagency response to detection of strains of avian influenza that have human health implications. As one response to these outbreaks, CDC issued an order on February 4, 2004 for an immediate ban on the import of all birds from most Southeast Asian countries. This order complemented a similar action taken by USDA.
CDC also works extensively with the US Department of the Interior and its relevant agencies. For example, the National Wildlife Health Center, U.S. Geologic Survey (USGS), in conjunction with CDC, has created a wildlife health bulletin that provides bird-handling guidelines for the general public, hunters, and field biologists. A monitoring program for influenza among wild birds in Alaska began in 2005 and is coordinated by the University of Alaska with collaboration from the USGS’s Fish and Wildlife Service, the Alaska Department of Health and Social Services, and CDC.
CDC also has created interim guidance for protection of persons with possible exposure to avian influenza during outbreaks among poultry, and guidance for persons involved in activities to control and eradicate outbreaks of avian influenza among poultry in the United States. Activities that could result in exposure to avian influenza-infected poultry include euthanasia, carcass disposal, and cleaning and disinfection of premises affected by avian influenza. The interim guidance, developed in cooperation with USDA should be considered complementary to avian population disease control and eradication strategies as determined by state governments, industry, and USDA.
CDC is also working closely with the Food and Drug Administration (FDA) and the agencies of the USDA to address potential human health issues related to the food supply, specifically the public’s concern about consuming poultry and egg products. FDA, USDA, and CDC are coordinating their efforts and working with the food industry to ensure that the public receives accurate messages about avian influenza and the safety of the food supply. There is no evidence that any human cases of avian influenza have been acquired by eating properly cooked poultry products. Influenza A viruses, such as H5N2, H7N2, and H5N1, are destroyed by adequate heat, as are other foodborne pathogens. The U.S. government has notified consumers to follow safe food preparation and handling practices and to cook all poultry and poultry products (including eggs) thoroughly before eating. Raw poultry can be associated with many infections, including salmonella, and always should be handled hygienically. Utensils, surfaces, and hands that come in contact with raw or partially cooked poultry should be cleaned carefully with water and soap immediately. WHO has developed specific food safety guidance for the current situation in Asia.
Additionally researchers at CDC have conducted studies on the incidence of adamantane resistance among influenza A viruses isolated worldwide from 1994 to 2005. Adamantanes are antiviral drugs that have been used to treat influenza A virus infections for many years. However, their use is rising worldwide, and viral resistance to the drugs has been reported among influenza A viruses (H5N1) strains isolated from poultry and humans in Asia. This data raises questions about the appropriate use of antiviral drugs, especially adamantines, and draws attention to the importance of tracing emergence and spread of drug resistant influenza A viruses. It is important to note that, although at present the H5N1 viruses isolated from people in Asia during the past two years appear to be resistant to adamantanes, they remain sensitive to neuraminidase inhibitors such as oseltamivir (Tamiflu®).
Development and Manufacture of Vaccine
Another important factor is that public demand for influenza vaccine in the United States varies annually. Having a steadily increasing demand would provide companies with a reliable, growing market that would be an incentive to increase their vaccine production capacity. In FY 2006, CDC will direct $40 million through the Vaccines for Children (VFC) program to purchase influenza vaccine for the national pediatric stockpile as additional protection against annual outbreaks of influenza. These funds to purchase vaccine can be used if needed during annual influenza seasons or possibly in a pandemic situation. HHS has also signed a $100 million contract with sanofi pasteur to develop cell culture vaccines. The President also 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.
Funds from the Strategic National Stockpile (SNS) have purchased approximately two million bulk doses of unfinished, unfilled H5N1 vaccine. This vaccine has not yet been formulated into vials, nor is the vaccine licensed by FDA. Clinical testing to determine dosage and schedule for this vaccine began in April 2005 with funding from NIH. Initial testing shows that, in its current form, a much higher volume of vaccine, up to 12 times as much as originally predicted, will be needed to produce the desired immune response in people. HHS therefore is supporting the development and testing of potential dose-sparing strategies that could allow a given quantity of vaccine stock to be used in more people. These strategies include developing adjuvants, substances added to a vaccine to aid its action, and the possibility of using intradermal rather than intramuscular injections. Such studies are currently underway, funded through the NIH. Additionally, HHS recently announced the award of a $62.5 million contract to the Chiron Corporation for the development of an H5N1 vaccine.
One of the main efforts by HHS in pandemic preparedness is to expand the nation’s use of influenza vaccine during inter-pandemic influenza seasons. This increase will help assure that the United States is better prepared for a pandemic. Influenza vaccine demand drives influenza vaccine supply. As we increase annual production efforts, this should strengthen our capacity for vaccine production during a pandemic. We are also developing strategies to increase influenza vaccine demand and access by persons who are currently recommended to receive vaccine each year.
HHS Pandemic Influenza Plan
In addition to outlining the federal response in terms of vaccines, surveillance, and planning, the HHS Pandemic Influenza plan makes clear the role of individual Americans in the event of an influenza pandemic. The importance of such ordinary but simple steps as frequent hand washing, containing coughs and sneezes, keeping sick children (and adults) home until they are fully recovered are widely seen as practical and useful for helping control the spread of infection. The plan also describes options for social-distancing actions, such as “snow days” and alterations in school schedules and planned large public gatherings. While such measures are, ordinarily, unlikely to fully contain an emerging outbreak, they may help slow the spread within communities.
State and Local Preparedness and Planning
CDC is 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.
Collaboration with the Council for State and Territorial Epidemiologists (CSTE) has considerably improved domestic surveillance through making 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, interim guidelines have been issued to states and hospitals for enhanced surveillance to identify potential H5N1 infections among travelers from affected countries, and these enhancements continue. Special laboratory training courses to teach state laboratory staff how to use molecular techniques to detect avian influenza have been held. In the past year, CDC trained professionals from all 48 states that desired training.
CDC has developed, with input from state and local health departments, and healthcare partners, guidance that provides healthcare facilities with recommendations for developing plans to respond to an influenza pandemic and guidance on the use of appropriate infection control measures to prevent transmission during patient care. Development of and participation in tabletop exercises over the past two years have identified gaps and provided recommendations for healthcare facilities to improve their readiness to respond and their integration in the overall planning and response efforts of their local and state health departments. The healthcare system has made great strides in preparation for a possible pandemic, but additional planning still needs to occur.
Enhancement of Quarantine Stations
Informing the Public
The outbreaks of avian influenza in Asia and Europe have highlighted several gaps in global disease surveillance that the United States must address in conjunction with partnering nations. These limitations include: 1) insufficient 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. The International Partnership the President established is also looking at how best to solve these challenges.
During an influenza pandemic, the presence of influenza vaccine manufacturing facilities in the United States will be critically important. The pandemic influenza vaccines produced in other countries are unlikely to be available to the U.S. market, because those governments have the power to prohibit export of the vaccines until their domestic needs are met. The U.S. vaccine supply is particularly fragile. Only one of four influenza vaccine manufacturers selling vaccine in the U.S. market makes its vaccine entirely in this country. It is necessary to ensure an enhanced and stable domestic influenza vaccine market to assure both supply and demand. Although the present avian influenza H5N1 strain in Southeast Asia does not yet have the capability of sustained person-to-person transmission, we are concerned that it could develop this capacity. CDC is closely monitoring the situation in collaboration with WHO, the affected countries, and other partners. We are using its extensive network with other federal agencies, provider groups, non-profit organizations, vaccine and antiviral manufacturers and distributors, and state and local health departments to enhance pandemic influenza planning. Additionally, the national response to the annual domestic influenza seasons provides a core foundation for how the nation will face and address pandemic influenza.
Thank you for the opportunity to share this information with you. I am happy to answer any questions.
Last Revised: June 6, 2006