National Vaccine Program Office

Table of Contents

• Influenza: Familiar, but Not Friendly
• Pandemics: How They Start, How They Spread, and Their Potential Impact
  • How Does a Pandemic Start?
  • How Does a Pandemic Spread?
  • The Phases of Pandemics
  • The Impact of a Pandemic: How Serious Might It Be?
• Pandemics and Pandemic Scares in the 20th Century
  • Historical Overview
  • 1918: Spanish Flu
  • 1957: Asian Flu
  • 1968: Hong Kong Flu
  • 1976: Swine Flu
  • 1977: Russian Flu
  • 1997: Avian Flu
• Ongoing Influenza Defense Tactics
  • Ongoing Surveillance
  • Vaccine Development
  • Anti-Viral Drugs
• Preparing for the Next Pandemic
  • FluAid 2.0
  • Links to Other Influenza Sites
• State and Local Pandemic Planning Guide
• The Public Health Training Network (PHTN)

Influenza: Familiar, but Not Friendly

The influenza (flu) epidemics that happen nearly every year are important events. Influenza is a respiratory illness that makes hundreds of thousands of people sick each year. The illness can cause severe health problems for the elderly and younger people with diseases, such as diabetes, heart or lung disease, and illness that can weaken the immune system. Typical primary influenza illness lasts about a week and is characterized by abrupt onset of fever, muscle aches, sore throat, and nonproductive cough. In some persons, severe malaise and cough can persist for several days or weeks.

Influenza infection not only causes primary illness but also can lead to severe secondary medical complications, including influenza viral pneumonia, secondary bacterial pneumonia, worsening of underlying medical conditions, such as congestive heart failure, asthma, or diabetes, or other complications such as ear infections (i.e., otitis media) in children.

Elderly persons (i.e., those 65 years and over) and persons with certain underlying medical conditions, such as chronic heart or lung disease, are at increased risk for developing complications from influenza infection. These complications increase the risk for hospitalization or death.

One of the most important features about influenza viruses is that their structure changes slightly but frequently over time (a process known as “drift”), and that this process results in the appearance of different strains that circulate each year. The composition of the flu vaccine is changed each year to help protect people from the strains of influenza virus that are expected to be the most common ones circulating during the coming flu season.

The ability of the vaccine to protect against influenza during a particular season depends on several factors, but particularly 1) the match between influenza strains in the vaccine and strains circulating in the community, and 2) the ability of each person's immune system to mount a protective response as a result of the vaccination. Although the vaccine may not prevent everyone who takes it from getting sick, it does reduce the risk of severe illness, hospitalization, and death. That's why it is so important for anyone who wants to reduce his or her risk of getting severely ill from influenza to receive the vaccine each year.

By contrast to the more gradual process of drift, in some years, the influenza virus changes dramatically and unexpectedly through a process known as “shift.” Shift results in the appearance of a new influenza virus to which few (if any) people are immune. If this new virus spreads easily from person to person, it could quickly travel around the world and cause increased levels of serious illness and death, affecting millions of people. This is called an influenza pandemic.

Fortunately, pandemics don't occur very often. There has not been an influenza pandemic since 1968. In 1997, however, a flu virus, that had previously infected only birds, caused an outbreak of illness in humans. This virus, known as the “avian flu,” resulted in 18 illnesses and six deaths in Hong Kong but did not easily spread from person to person. Still, it provided a frightening reminder that the next pandemic could occur at any time. Governments around the world took notice. The U.S. government worked with State and local governments, and private-sector partners, to develop strategies and programs that would prepare our country for a pandemic.

Influenza Pandemics: How They Start, How They Spread, and Their Potential Impact

How Does an Influenza Pandemic Start?

There are three main types of influenza viruses: A, B, and C. Influenza C causes only mild disease and has not been associated with widespread outbreaks. Influenza types A and B, however, cause epidemics nearly every year. Influenza A viruses are divided into subtypes, based on differences in two surface proteins: hemagglutinin (H) and neuraminidase (N). Influenza B viruses are not divided into subtypes. During an influenza flu season, usually one or more influenza A subtype and B viruses circulate at the same time.

A pandemic is possible when an influenza A virus makes a dramatic change (i.e., "shift") and acquires a new H or H+N. This shift results in a new or "novel" virus to which the general population has no immunity. The appearance of a novel virus is the first step toward a pandemic. However, the novel influenza A virus also must spread easily from person to person (and cause serious disease) for a pandemic to occur. Influenza B viruses do not undergo shift and do not cause influenza pandemics.

The reservoir for Type A influenza viruses is wild birds, but influenza A viruses also infect animals such as pigs and horses, as well as people. The last two pandemic viruses were combinations of bird and human influenza viruses. Many persons believe that these new viruses emerged when an intermediate host, such as a pig, was infected by both human and bird influenza A viruses at the same time. A new virus was created. Events in Hong Kong in 1997, however, showed that this is not the only way that humans can become infected with a novel virus. Sometimes, an avian influenza virus can "jump the species barrier" and move directly from chickens to humans and cause disease.

Since, by definition, a novel virus is a virus that has never previously infected humans, or hasn't infected humans for a long time, it's likely that almost no one will have immunity, or antibody to protect them against the novel virus. Therefore, anyone exposed to the virus--young or old, healthy or weak--could become infected and get sick. If the novel virus is related to a virus that circulated long ago, older people might have some level of immunity. It is possible that the novel virus may be especially dangerous to some age groups that are not usually at risk of severe illness or death from annual influenza (such as healthy young adults). Such widespread vulnerability makes a pandemic possible and allows it to have potentially devastating impact.

How Does a Pandemic Spread?

Although all pandemics begin with the appearance of a novel virus, most novel viruses do not spread and cause pandemics. It's more common for a novel virus to be detected and cause illness in a few people, but not go on to infect large numbers of people.

For a novel virus to cause a pandemic, a sequence of events must occur over time. A planning tool, developed by pandemic planners, of how those events might unfold can be found at the following web site: www.who.int/emc-documents/influenza/whoccscsredc991c.html. However, the phases will not occur simultaneously around the world.

The Phases of a Pandemic

To help prepare and respond to a pandemic, WHO has developed a series of "phases" that can be used by planners.

• Phase 0, Preparedness Level 0
  ( Inter-Pandemic Period )
   
  Every year, there are three or four strains of influenza viruses moving around the world and causing illness. In a normal year (the pre-pandemic period), all of these viruses will be previously identified strains and will be similar to other strains recently circulating. A vaccine, that covers the strains most likely to circulate during the influenza season, is developed each year. Vaccine is usually administered between October and December each year in the U.S.
   
• Phase 0, Preparedness Level 1
  (Initial Report of a New Strain in Humans)
   
  Occasionally there are reports of isolation of a novel virus from humans without clear evidence of spread from person to person or of outbreak activity. Each report of a novel virus is investigated and, depending on what is learned, we may or may not advance to the next stage of the model.
   
• Phase 0, Preparedness Level 2
  (Novel Virus Alert - Human Infection Confirmed)
   
  A Novel Virus Alert occurs when two or more human infections (with a novel virus) have been confirmed. The ability of the virus to spread from human to human and cause serious disease, however, is still questionable. Human infections with novel viruses have often been seen in Asia first, but a novel virus can be found anywhere. For example, the 1976 novel virus, known as swine flu, originated in Fort Dix, New Jersey.
   
• Phase 0, Preparedness Level 3
  (Human Transmission Confirmed)
   
  This Preparedness Level will exist when human transmission of the new virus sub-type has been confirmed through clear evidence of person-to-person spread in the general population, such as secondary cases resulting from contact with an index case, with at least one outbreak lasting over a minimum two week period in one country. Identification of the new virus sub-type in several countries, with no explanation other than contact among infected people, may also be used as evidence for significant human transmission.
   
• Phase 1
  (Confirmation of Onset of Pandemic)
   
  To progress from a Novel Virus Alert to Pandemic Imminent, a novel virus must be able to spread efficiently from one person to another. In this phase, the virus is causing several outbreaks in at least one country; it has spread to other countries and disease patterns indicate that severe morbidity and mortality (sickness and death) are likely in at least one segment of the population. The 1997 avian flu virus never efficiently spread from one person to another, so Pandemic Imminent was never declared.
   
• Phase 2
  (Regional and Multi-Regional Epidemics)
   
  The Pandemic phase occurs when the novel virus is causing outbreaks and epidemics in multiple countries around the world. If a community has not prepared itself well before this phase, it may be suddenly facing some very serious public health, social, and economic problems. Fortunately, it is extremely rare for a novel virus to progress to the Pandemic phase. It hasn't happened since the Hong Kong flu of 1968.
   
• Phase 3
  (End of First Pandemic Wave)
   
  Influenza activity in initially affected countries/regions has stopped while outbreaks of the new viruses are continuing elsewhere. During this "downtime," it is important to maintain enthusiasm for the pandemic response by continuing vaccination campaigns and other response efforts. This may be the time when we have a chance to "catch up" to the virus.
   
• Phase 4
  (Second or Later Waves of the Pandemic)
   
  Based on past experiences, at least a second wave of outbreaks caused by the novel virus would be expected to occur within 3-9 months of the initial epidemic in a particular country or region.
   
• Phase 5
  (End of the Pandemic - Back to Phase 0)
   
  The pandemic is declared "over" when the infection rate of influenza returns to pre-pandemic levels, and no more large-scale "waves" of illness are expected. Based on history, it could take two years for this to happen. Once it happens, the cycle begins again.

While there is no way to identify exactly when each of the phases will occur, it is estimated that an average pandemic could progress from a Novel Virus Alert to a Pandemic in a matter of months. This time frame could be much longer if the disease is not readily contagious, or it could be shorter if the virus spreads quickly.

The phases described above have been developed to help pandemic planners figure out what to do in conjunction with the changing epidemiology of a novel virus. It's important to understand that actual spread of the virus may or may not be described by these phases. For example, we may not be aware of a novel virus until after it has caused widespread disease. For this reason, pandemic plans must include the flexibility to respond to the specifics of each pandemic virus.

The Impact of a Pandemic: How Serious Might It Be?

There's no simple answer to the question of how serious a pandemic might be. It all depends on how virulent (severe) the virus is, how rapidly it can spread from population to population, and the effectiveness of pandemic prevention and response efforts. The 1918 Spanish flu is an example of a worst-case scenario because the strain was highly contagious and quite deadly. This pandemic killed more Americans than all the wars of the 20th century. Since our world today is vastly more populated, and people travel the globe with ease, the spread of a next pandemic could be more rapid than that of previous pandemics.

The impact of a pandemic isn't measured only by how many people will die. If millions of people get sick at the same time, major social consequences will occur. If many doctors and nurses become ill, it will be difficult to care for the sick. If the majority of a local police force is infected, the safety of the community might be at risk. If air traffic controllers are all sick at once, air travel could grind to a halt, interrupting not only business and personal travel, but also the transport of life-saving vaccines or anti-viral drugs. Therefore, a vital part of pandemic planning is the development of strategies and tactics to address all these potential problems.

Pandemics and Pandemic Scares in the 20th Century

Historical Overview

History suggests that influenza pandemics have probably happened during at least the last four centuries. During the 20th century, three pandemics and several "pandemic scares" occurred. These are described in more detail below.

1918: Spanish Flu

The Spanish Influenza pandemic is the catastrophe against which all modern pandemics are measured. It is estimated that approximately 20 to 40 percent of the worldwide population became ill and that over 20 million people died. Between September 1918 and April 1919, approximately 500,000 deaths from the flu occurred in the U.S. alone. Many people died from this very quickly. Some people who felt well in the morning became sick by noon, and were dead by nightfall. Those who did not succumb to the disease within the first few days often died of complications from the flu (such as pneumonia) caused by bacteria.

One of the most unusual aspects of the Spanish flu was its ability to kill young adults. The reasons for this remain uncertain. With the Spanish flu, mortality rates were high among healthy adults as well as the usual high-risk groups. The attack rate and mortality was highest among adults 20 to 50 years old. The severity of that virus has not been seen again.

1957: Asian Flu

In February 1957, the Asian influenza pandemic was first identified in the Far East. Immunity to this strain was rare in people less than 65 years of age, and a pandemic was predicted. In preparation, vaccine production began in late May 1957, and health officials increased surveillance for flu outbreaks.

Unlike the virus that caused the 1918 pandemic, the 1957 pandemic virus was quickly identified, due to advances in scientific technology. Vaccine was available in limited supply by August 1957. The virus came to the U.S. quietly, with a series of small outbreaks over the summer of 1957. When U.S. children went back to school in the fall, they spread the disease in classrooms and brought it home to their families. Infection rates were highest among school children, young adults, and pregnant women in October 1957. Most influenza-and pneumonia-related deaths occurred between September 1957 and March 1958. The elderly had the highest rates of death.

By December 1957, the worst seemed to be over. However, during January and February 1958, there was another wave of illness among the elderly. This is an example of the potential "second wave" of infections that can develop during a pandemic. The disease infects one group of people first, infections appear to decrease and then infections increase in a different part of the population. Although the Asian flu pandemic was not as devastating as the Spanish flu, about 69,800 people in the U.S. died.

1968: Hong Kong Flu

In early 1968, the Hong Kong influenza pandemic was first detected in Hong Kong. The first cases in the U.S. were detected as early as September of that year, but illness did not become widespread in the U.S. until December. Deaths from this virus peaked in December 1968 and January 1969. Those over the age of 65 were most likely to die. The same virus returned in 1970 and 1972. The number of deaths between September 1968 and March 1969 for this pandemic was 33,800, making it the mildest pandemic in the 20th century.

There could be several reasons why fewer people in the U.S. died due to this virus. First, the Hong Kong flu virus was similar in some ways to the Asian flu virus that circulated between 1957 and 1968. Earlier infections by the Asian flu virus might have provided some immunity against the Hong Kong flu virus that may have helped to reduce the severity of illness during the Hong Kong pandemic. Second, instead of peaking in September or October, like pandemic influenza had in the previous two pandemics, this pandemic did not gain momentum until near the school holidays in December. Since children were at home and did not infect one another at school, the rate of influenza illness among schoolchildren and their families declined. Third, improved medical care and antibiotics that are more effective for secondary bacterial infections were available for those who became ill.

1976: Swine Flu Scare

When a novel virus was first identified at Fort Dix, it was labeled the "killer flu." Experts were extremely concerned because the virus was thought to be related to the Spanish flu virus of 1918. The concern that a major pandemic could sweep across the world led to a mass vaccination campaign in the United States. In fact, the virus--later named "swine flu"--never moved outside the Fort Dix area. Research on the virus later showed that if it had spread, it would probably have been much less deadly than the Spanish flu.

1977: Russian Flu Scare

In May 1977, influenza A/H1N1 viruses isolated in northern China, spread rapidly, and caused epidemic disease in children and young adults (< 23 years) worldwide. The 1977 virus was similar to other A/H1N1 viruses that had circulated prior to 1957. (In 1957, the A/H1N1 virus was replaced by the new A/H2N2 viruses). Because of the timing of the appearance of these viruses, persons born before 1957 were likely to have been exposed to A/H1N1 viruses and to have developed immunity against A/H1N1 viruses. Therefore, when the A/H1N1 reappeared in 1977, many people over the age of 23 had some protection against the virus and it was primarily younger people who became ill from A/H1N1 infections. By January 1978, the virus had spread around the world, including the United States. Because illness occurred primarily in children, this event was not considered a true pandemic. Vaccine containing this virus was not produced in time for the 1977-78 season, but the virus was included in the 1978-79 vaccine.

1997: Avian Flu Scare

The most recent pandemic "scares" occurred in 1997 and 1999. In 1997, at least a few hundred people became infected with the avian A/H5N1 flu virus in Hong Kong and 18 people were hospitalized. Six of the hospitalized persons died. This virus was different because it moved directly from chickens to people, rather than having been altered by infecting pigs as an intermediate host. In addition, many of the most severe illnesses occurred in young adults similar to illnesses caused by the 1918 Spanish flu virus. To prevent the spread of this virus, all chickens (approximately 1.5 million) in Hong Kong were slaughtered. The avian flu did not easily spread from one person to another, and after the poultry slaughter, no new human infections were found.

In 1999, another novel avian flu virus – A/H9N2 – was found that caused illnesses in two children in Hong Kong. Although both of these viruses have not gone on to start pandemics, their continued presence in birds, their ability to infect humans, and the ability of influenza viruses to change and become more transmissible among people is an ongoing concern.

Ongoing Influenza Defense Tactics

Fighting the flu in the U.S. is a yearly battle that requires the combined resources of the Department of Health and Human Services, the World Health Organization (WHO), vaccine and drug companies, State and local health authorities, and the medical community.

Early detection of changes in influenza viruses and rapid development of effective vaccines are the keys to defending against influenza each year and responding to the possibility of a pandemic. The cycle of surveillance and vaccine formulation is a never-ending process.

Ongoing Surveillance

The first line of defense against influenza is a worldwide surveillance system coordinated by WHO. This system makes it possible for changes in circulating influenza viruses and the emergence of novel influenza A viruses to be detected as soon as possible.

The task of identifying circulating strains of influenza--whether known or novel--is done by a worldwide network of 110 National Influenza Centers and many other WHO laboratories in 83 countries. WHO Collaborating Reference Centers for Influenza in London, Atlanta, Melbourne, and Tokyo coordinate the system and intensively analyze samples of virus isolated and collected by approximately 180 laboratories.

Each year, some influenza virus isolates from laboratories in the U.S. and overseas are sent to the Centers for Disease Control and Prevention (CDC) in Atlanta. Tests are done to determine the antigenic and molecular make-up of the viruses. CDC examines the viruses to determine which are the most important emerging influenza viruses, and their ability to cause outbreaks, and then provides this information at yearly meetings held by the Food and Drug Administration (FDA) and by WHO so it can be used to formulate vaccine for the next influenza season.

During January through March, WHO, The Food and Drug Administration (FDA), and CDC undertake the process of deciding which strains will be selected for vaccine production in the U.S.

In addition, the CDC actively monitors U.S. disease activity and deaths related to influenza between October and May of each year. This information is provided each week in influenza surveillance summaries.

B. Vaccine Development

The best method of preventing and reducing the severity of the flu is the timely development, distribution, and administration of influenza vaccine. The influenza vaccine used each year is an inactivated trivalent vaccine. This means that the flu vaccine contains three inactivated (or "killed") flu viruses that protect against three different strains of influenza virus (one influenza B and two influenza A strains). Because the current licensed vaccines are inactivated vaccines, flu vaccine cannot cause the flu – a common misperception. The effectiveness of the trivalent vaccine depends upon the "match" between strains of influenza that are circulating and the viruses in the vaccine. Although there is no guarantee that the strains picked for the vaccine will be the strains that go around during the following flu season, the match between vaccine strains and circulating strains is good about 90 percent of the time.

The vaccine strain selection process requires surveillance information collected year-round. In late January of each year, the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) reviews worldwide surveillance data. The Committee usually makes an initial recommendation about at least one of the three strains to be included in the vaccine. By mid-February, the WHO completes its review and makes recommendations for the Northern Hemisphere vaccine. The WHO repeats this process in September for Southern Hemisphere vaccine recommendations. In March, VRBPAC meets to finalize the recommendations for the U.S. influenza vaccine.

While the vaccine strain selection process is going on, the four influenza vaccine manufacturers licensed in the U.S. begin preparations for vaccine production. Because flu vaccine viruses are grown inside eggs, manufacturers must buy enough eggs to manufacture 80 million or more doses of vaccine. The FDA prepares the specific viral material for the manufacturers to use, in order to begin vaccine production. During the manufacturing process, the live viral ingredient is killed so that the vaccine will not cause people to become sick with the flu. As the manufacturers produce vaccine, FDA reviews safety data. The last steps of vaccine preparation include production and bottling of vaccine, distribution to vaccine providers, and administration to patients. All this must be done in time for vaccination campaigns to begin by late September.

Working closely with State and local health authorities, partners in the private sector, CDC, FDA, and vaccine manufacturers have built a successful program for vaccine delivery each year. CDC and its Advisory Committee on Immunization Practices (ACIP) issue recommendations each year for the prevention and control of influenza. ACIP strongly recommends influenza vaccine for any person, 6 months of age or older, who is at increased risk for complications of influenza. Groups at increased risk include persons 65 years of age and older; residents of nursing homes and other chronic-care facilities; adults and children with chronic lung, heart, metabolic, kidney, or immune system disorders; and women who will be in the 2nd or 3rd trimester of pregnancy during the influenza season. Influenza vaccine also should be given to people who have close contact with high-risk persons, such as health care providers, family members of such persons, and others such as medical volunteers. The reason for vaccinating the close contacts is to prevent transmission of flu viruses to people who are at high risk for developing serious complications from flu. Influenza vaccine should also be administered to any person who wishes to reduce the likelihood of becoming ill with influenza.

C. Antiviral Drugs

In addition to vaccines, antiviral drugs are available for both the prevention and treatment of influenza. Currently, there are two classes of drugs--adamantines and neuraminidase inhibitors. The amantadines (amantadine and rimantadine), are approved for the treatment and prophylaxis of influenza A only. The neuraminidase inhibitors (zanamivir and oseltamivir) have activity against both influenza A and B, but are currently approved by FDA only for treatment.

To prevent the flu, antiviral drugs must be taken consistently before infection occurs. When used to reduce the impact of the flu for someone who is already infected, antiviral drugs must be taken within two days after flu symptoms start. It is important to know that antiviral drugs can have some potentially serious side effects.

In non-pandemic situations, antiviral drugs have been useful in helping to control outbreaks in settings such as nursing homes, where many people could become sick with flu and develop serious complications. In addition, antivirals can be useful in preventing influenza in certain individuals who have a weakened immune system and therefore, would not respond to the vaccine, or those who have a known allergic reaction to the vaccine. There are important differences among the influenza antiviral drugs, including age approved indications, side effects, and costs. A knowledgeable health care professional should be consulted when they are used.

During a pandemic, antiviral drugs are likely to play an important, but limited role. Guidelines are being developed to address how antiviral drugs should be used during a pandemic.

Preparing for the Next Pandemic

In the event of a pandemic, good surveillance, timely vaccine development and production, and the ability to administer vaccine to large numbers of people in a short amount of time will be very important.

The vaccination program during a pandemic will probably be different from current annual flu shot programs in several respects

• More people will want and need to be vaccinated, so we will need a larger supply of vaccine.
  
  
• The warning period before a pandemic is likely to be short. Because the current vaccine manufacturing process takes a minimum of 6 months, it is likely that there will not be enough vaccine at the beginning of a pandemic to vaccinate everyone who wants it.
  
  
• It may be necessary for an individual to receive two doses of vaccine to be fully protected against the virus.

In addition, communication and emergency response systems will have to be in place to assist in managing a pandemic.

Since 1993, Federal, State and local health officials have been working on several different preparedness efforts to reduce pandemic influenza-related deaths, sickness, and social disruption. One of the efforts is to develop a national plan that will cover many important aspects of responding to the next pandemic, including 1) enhancing surveillance and early detection of a novel virus, and 2) improving the public health infrastructure so pandemic-related programs can be effectively administered.

Another important effort has been to assist State and local public health and emergency response officials in preparing pandemic plans specific to their jurisdiction, the national Working Group on Influenza Pandemic Preparedness and Emergency Response has developed A Planning Guide for State and Local Officials (Draft 2.1) in collaboration with the Council of State and Territorial Epidemiologists (CSTE). Major planning and response elements included in this Guide are intended to convey important items to consider in the planning process, with each jurisdiction assuming responsibility for deciding how each item is implemented. It is also recognized that a number of actions taken by State and local agencies will be contingent upon the development of national policies and procedures, many of which are presently under development.

FluAid 2.0, software and manual to aid State and local-level public health officials plan, prepare, and practice for the next influenza pandemic, is also available (in a beta test version) for those who are interested in modeling the impact a pandemic might have on their community. The software is designed to provide a range of estimates of impact in terms of deaths, hospitalizations, and outpatient visits due to pandemic influenza. The software does NOT provide any description of how the pandemic will spread, i.e., when a specific community will be affected. For more information on FluAid 2.0 or to obtain a copy, contact Martin Meltzer, Ph.D., Centers for Disease Control and Prevention, NCID/OD/OS, Mailstop D-59, 1600 Clifton Road, Atlanta, GA 30333, E-mail: qzm4@cdc.gov.

Work is underway to develop a pandemic influenza gateway site that will be maintained by the National Vaccine Program Office. During inter-pandemic periods, the site will contain only basic information. In the event that a pandemic appears imminent, all of the links from this site and other special features of the site will be activated.

Links To Other Influenza Sites

1. The National Immunization Program (NIP), CDC
(http://www.cdc.gov/nip)
The NIP is a part of the Centers for Disease Control and Prevention, located in Atlanta, Georgia. As a disease-prevention program, NIP provides leadership for the planning, coordination, and conduct of immunization activities nationwide.

2. Influenza Branch, National Center for Infectious Diseases, CDC
(http://www.cdc.gov/ncidod/diseases/flu/fluvirus.htm)
The Influenza Branch provides leadership for the prevention and control of influenza in the U.S. and worldwide. Major activities include coordinating surveillance and conducting research. The Influenza Prevention and Control home page (http://www.cdc.gov/ncidod/diseases/flu/fluvirus.htm) contains information on influenza vaccine, antiviral agents, and surveillance.

The Influenza Branch operates one of the four World Health Organization (WHO) Collaborative Centers for Reference and Research on Influenza and is the main reference laboratory for characterizing influenza viruses in the U.S. and North America. It also:

• Characterizes influenza viruses circulating in the U.S. and worldwide, using molecular and serological techniques to detect new strains and the emergence of viruses with pandemic potential.
  
• Coordinates U.S. influenza surveillance and publishes a weekly influenza surveillance update (http://www.cdc.gov/ncidod/diseases/flu/weekly.htm) from October through May.

3. Center for Biologics Evaluation and Research (CBER), FDA
(http://www.fda.gov/cber/index.htm)
The mission of CBER is to protect and enhance the public health through regulation of biological products including blood, vaccines, therapeutics and related drugs and devices according to statutory authority. The regulation of these products is founded on science and law to ensure their purity, potency, safety, efficacy, and availability. CBER plays a critical role in the manufacture and licensing of influenza vaccine.

4. National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID),
(http://www.niaid.nih.gov/)
The National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, conducts and supports research aimed at finding better ways to treat and prevent influenza infections. This site includes NIAID fact sheets, brochures and news releases on influenza, as well as links to influenza information maintained by other federal agencies.

5. Animal and Plant Health Inspection Service, Veterinary Services, U.S. Department of Agriculture
(http://www.aphis.usda.gov/)
The U.S. Department of Agriculture, Animal and Plant Health Inspection Service (APHIS), Veterinary Services (VS) protects the health, quality, and marketability of our nation's livestock and poultry resources. Within VS, the Emergency Programs staff (http://www.aphis.usda.gov/oa/emergency.html) coordinates efforts to prepare for and respond to outbreaks of exotic animal diseases including highly pathogenic avian influenza. Surveillance for influenza A viruses in avian species in the U.S. are reported each year by the USDA, APHIS, VS, National Veterinary Services Laboratories in the Proceedings of the U.S. Animal Health Association Annual Meeting (http://www.usaha.org/reports/poult97.html).

6. The USDA Agricultural Research Service (ARS)
(http://www.ars.usda.gov/)
The ARS conducts research to develop and transfer solutions to agricultural problems of high national priority and provides information access and dissemination. The ARS' Southeast Poultry Research Laboratory (http://seprlars.usda.gov/) publishes information on avian influenza research and contacts for further information.

7. The Department of Defense Global Emerging Infections Surveillance and Response System
(http://www.geis.ha.osd.mil/main2.html).
(DoD-GEIS) was created in response to Presidential Decision Directive NSTC-7. In the directive, former President Clinton recognized the threat posed by emerging infectious diseases to the health of our global community and to our national security. Responsibilities and actions to improve our Nation's ability to identify and respond to the threat are assigned to many organizations and agencies, including the DoD.

8. The World Health Organization
(http://www.who.org)
The World Health Organization's Influenza Programme
(http://www.who.org) (http://who.int/emc/diseases/flu/) was created in 1946 as an international centre to collect and distribute information, coordinate laboratory work on influenza and train laboratory workers. After 50 years, WHO's global surveillance of influenza now maintains 110 National Influenza Centres in 83 countries and four WHO Collaborating Centres for Virus Reference and Research in Atlanta, USA; London, UK; Melbourne, Australia; and Tokyo, Japan.

HHS Home | Questions? | Contact HHS | Accessibility | Privacy Policy | FOIA | Disclaimers

The White House | USA.gov | Helping America's Youth

U.S. Department of Health & Human Services · 200 Independence Avenue, S.W. · Washington, D.C. 20201