Influenza pandemic

An influenza pandemic is a large scale epidemicof the influenzavirus, such as the 1918Spanish flu. The World Health Organization(WHO) warns that there is a substantial risk of an influenza pandemicwithin the next few years. One of the strongest candidates is the A(H5N1) subtype of avian influenza.

Nature of a pandemic

In a bad pandemic, some communities cut themselves off totally while others have half their population die. People try every remedy they can think of. [1]There are not enough doctors, hospital rooms, or medical supplies for the living and dead bodies pile up faster than they can be dealt with. There is great social disruption and efforts to deal with the pandemic always leave a great deal to be desired due to selfishness, lack of trust, illegal behavior, and ignorance. For example in the 1918 pandemic "This horrific disconnect between reassurances and reality destroyed the credibility of those in authority. People felt they had no one to turn to, no one to rely on, no one to trust." [2]

A letter from a physician at one U.S. Army camp in the 1918 pandemic said:

It is only a matter of a few hours then until death comes [...]. It is horrible. One can stand it to see one, two or twenty men die, but to see these poor devils dropping like flies [...]. We have been averaging about 100 deaths per day [...]. Pneumonia means in about all cases death [...]. We have lost an outrageous number of Nurses and Drs. It takes special trains to carry away the dead. For several days there were no coffins and the bodies piled up something fierce [...]. [3]

Comes in waves

Flu pandemics typically come in waves. The 1889?1890 and the 1918-1919 flu pandemics each came in three or four waves with the initial waves being less deadly than following waves. [4]But within a wave, mortality was greater at the beginning of the wave. [5]

Variable mortality

Mortality varies widely in a pandemic. In the 1918pandemic:

In U.S. Army camps where reasonably reliable statistics were kept, case mortality often exceeded 5 percent, and in some circumstances exceeded 10 percent. In the British Army in India, case mortality for white troops was 9.6 percent, for Indian troops 21.9 percent. In isolated human populations, the virus killed at even higher rates. In the Fiji islands, it killed 14 percent of the entire population in 16 days. In Labrador and Alaska, it killed at least one-third of the entire native population. [6]

Strategies to prevent a pandemic

If avian influenza remains an animal problem with limited human-to-human transmission it is not a pandemic, though it continues to pose a risk.

To prevent the situation from progressing to a pandemic, the following short-term strategies have been put forward:

• Culling and vaccinatinglivestock
• Vaccinating poultry workers against common flu
• Limiting travel in areas where the virus is found

The rationale for vaccinating poultry workers against common flu is that it reduces the probability of common influenza virus recombining with Avian H5N1 virus in the bloodstream of poultry workers to form a pandemic strain.

Longer term strategies proposed for regions where highly pathogenic H5N1 is endemic in wild birds have included:

• changing local farmingpractices to increase farm hygiene and reduce contact between livestockand wild birds.
• altering farming practices in regions where animals live in close, often unsanitary quarters with people, and changing the practices of open-air "wet markets" where birds are slaughtered in unsanitary conditions near fruits and vegetables. Cock fightingalso has played a role in spreading the disease by bringing humans into contact with fowl, and this practice will also continue to contribute to infection if it is not curbed. A challenge to implementing these measures is widespread poverty, frequently in rural areas, coupled with a reliance upon raising fowl for purposes of subsistence farmingor income without measures to prevent propagation of the disease.
• changing local shopping practices from purchase of live fowl to purchase of slaughtered, pre-packaged fowl.
• improving veterinary vaccineavailability and cost. [7]

Strategies to slow down a pandemic

Vaccines

A vaccineprobably would not be available in the inital stages of population infection [8]. Once a potential virus is identified, it normally takes at least several months before a vaccine becomes widely available, as it must be developed, tested and authorized. The capability to produce vaccines varies widely from country to country; in fact, only 15 countries are listed as "Influenza vaccine manufacturers" according to the World Health Organization [9]. It is estimated that, in a best scenario situation, 750 million doses could be produced each year, whereas it is likely that each individual would need two doses of the vaccine in order to become inmuno-competent. Distribution to and inside countries would probably be problematic [10]. Several countries, however, have well-developed plans for producing large quantities of vaccine. For example, Canadianhealth authorities say that they are developing the capacity to produce 32 million doses within four months, enough vaccine to inoculate every person in the country. [11] In New Zealand, the government has spent $26 million on a preparedness program. They are catering for up to 1 million people affected, and 20,000 hospitalized, in a population of 4 million. The government requires 850,000 doses of Tamiflu, and Rochecannot keep up with private demand. [12]

United States

According to the US HHS (United StatesDepartment of Health & Human Services) Pandemic Influenza Plan Appendix F: Current HHS Activities last revised on November 8, 2005 and located here:

Currently, influenza vaccine for the annual, seasonal influenza program comes from four manufacturers. However, only a single manufacturer produces the annual vaccineentirely within the U.S. Thus, if a pandemic occurred and existing U.S.-based influenza vaccine manufacturing capacity was completely diverted to producing a pandemic vaccine, supply would be severely limited. Moreover, because the annual influenza manufacturing process takes place during most of the year, the time and capacity to produce vaccine against potential pandemic viruses for a stockpile, while continuing annual influenza vaccine production, is limited. Since supply will be limited, it is critical for HHS to be able to direct vaccine distribution in accordance with predefined groups (see Appendix D); HHS will ensure the building of capacity and will engage states in a discussion about the purchase and distribution of pandemic influenza vaccine.

Vaccine production capacity: The protective immune response generated by current influenza vaccines is largely based on viral hemagglutinin(HA) and neuraminidase(NA) antigensin the vaccine. As a consequence, the basis of influenza vaccine manufacturing is growing massive quantities of virus in order to have sufficient amounts of these protein antigens to stimulate immune responses. Influenza vaccines used in the United States and around world are manufactured by growing virus in fertilized hens? eggs, a commercial process that has been in place for decades. To achieve current vaccine production targets millions of 11-day old fertilized eggs must be available every day of production.

In the near term, further expansion of these systems will provide additional capacity for the U.S.-based production of both seasonal and pandemic vaccines, however, the surge capacity that will be needed for a pandemic response cannot be met by egg-based vaccine production alone, as it is impractical to develop a system that depends on hundreds of millions of 11-day old specialized eggs on a standby basis. In addition, because a pandemic could result from an avian influenzastrain that is lethal to chickens, it is impossible to ensure that eggs will be available to produce vaccine when needed.

In contrast, cell culturemanufacturing technologycan be applied to influenza vaccines as they are with most viral vaccines (e.g., poliovaccine, measles-mumps-rubellavaccine, chickenpoxvaccine). In this system, viruses are grown in closed systems such as bioreactorscontaining large numbers of cells in growth media rather than eggs. The surge capacity afforded by cell-based technology is insensitive to seasons and can be adjusted to vaccine demand, as capacity can be increased or decreased by the number of bioreactors or the volume used within a bioreactor. In addition to supporting basic research on cell-based influenza vaccine development, HHS is currently supporting a number of vaccine manufacturers in the advanced development of cell-based influenza vaccines with the goal of developing U.S.-licensed cell-based influenza vaccines produced in the United States.

Dose-sparing technologies. Current U.S.-licensed vaccines stimulate an immuneresponse based on the quantity of HA (hemagglutinin) antigenincluded in the dose. Methods to stimulate a strong immune response using less HA antigen are being studied in H5N1and H9N2vaccine trials. These include changing the mode of delivery from intramuscular to intradermal and the addition of immune-enhancing adjuvant to the vaccine formulation. Additionally, HHS is soliciting contract proposals from manufacturersof vaccines, adjuvants, and medical devicesfor the development and licensure of influenza vaccines that will provide dose-sparing alternative strategies.

Anti-viral drugs

Several new anti-viral drugshave been developed in recent years. A number of governments are working to stockpile anti-viral drugs but the work is complicated by the constant mutation of the virus, some strains of which have already shown resistance to Tamiflu.

Other

(The World Health Organizationpublished a compendium of non-pharmaceutical interventionsin November 2005. The following list is not identical to the WHO recommendations.)

• • Social distance. By travelling less, working from home or closing schools there is less opportunity for the virus to spread.
  • Respiratory etiquette. Placing one's hand in front of the mouth when coughing or sneezing can somewhat limit the dispersal of droplets. However It has been suggested recently that covering one's mouth and nose with one's hand is not very effective in stopping the spread of germs as these germs are retained in the hand, and are then deposited on doorknobs, on to others through handshakes, etc. Current thinking suggests coughing or sneezing into the crook of one's arm would be preferable to limit germ spread.
  • Masks. No mask can provide a perfect barrier but products that meet or exceed the NIOSHN95 standard recommended by the World Health Organizationare thought to provide good protection. WHOrecommends that health-care workers wear N95 masks and that patients wear surgical masks (which may prevent respiratory secretions from becoming airborne) [13]. Any mask may be useful to remind the wearer not to touch his face. This can reduce infection due to contact with contaminated surfaces, especially in crowded public places where coughing or sneezing people have no way of washing their hands. The mask itself can become contaminated and must be handled as medical waste when removed.
  • Hygiene. Frequent handwashing, especially when there has been contact with other people or with potentially contaminated surfaces can be very helpful. Alcohol-based hand sanitizers also kill both bacteria and viruses.[14]

Strategies for individuals in a pandemic

Source: http://pandemicflu.gov/plan/tab3.html

Social Disruption May Be Widespread

• Plan for the possibility that usual services may be disrupted. These could include services provided by hospitals and other health care facilities, banks, stores, restaurants, government offices, and post offices.
• Prepare backup plans in case public gatherings, such as volunteer meetings and worship services, are canceled.
• Consider how to care for people with special needs in case the services they rely on are not available.

Being Able to Work May Be Difficult or Impossible

• Find out if you can work from home.
• Ask your employer about how business will continue during a pandemic. (A Business Pandemic Influenza Planning Checklist is available at www.pandemicflu.gov/plan/businesschecklist.html.)
• Plan for the possible reduction or loss of income if you are unable to work or your place of employment is closed.
• Check with your employer or union about leave policies.

Schools May Be Closed for an Extended Period of Time

• Help schools plan for pandemic influenza. Talk to the school nurse or the health center. Talk to your teachers, administrators, and parent-teacher organizations.
• Plan home learning activities and exercises. Have materials, such as books, on hand. Also plan recreational activities that your children can do at home.
• Consider childcare needs.

Transportation Services May Be Disrupted

• Think about how you can rely less on public transportation during a pandemic. For example, store food and other essential supplies so you can make fewer trips to the store.
• Prepare backup plans for taking care of loved ones who are far away.
• Consider other ways to get to work, or, if you can, work at home.

People Will Need Advice and Help at Work and Home

• Think about what information the people in your workplace will need if you are a manager. This may include information about insurance, leave policies, working from home, possible loss of income, and when not to come to work if sick. (A Business Pandemic Influenza Planning Checklist is available at www.pandemicflu.gov/plan/businesschecklist.html.)
• Meet with your colleagues and make lists of things that you will need to know and what actions can be taken.
• Find volunteers who want to help people in need, such as elderly neighbors, single parents of small children, or people without the resources to get the medical help they will need.
• Identify other information resources in your community, such as mental health hotlines, public health hotlines, or electronic bulletin boards.
• Find support systems?people who are thinking about the same issues you are thinking about. Share ideas.

Be Prepared

Stock a supply of water and food. During a pandemic you may not be able to get to a store. Even if you can get to a store, it may be out of supplies. Public waterworks services may also be interrupted. Stocking supplies can be useful in other types of emergencies, such as power outages and disasters. Store foods that:

• are nonperishable (will keep for a long time) and don?t require refrigeration
• are easy to prepare in case you are unable to cook
• require little or no water, so you can conserve water for drinking

Stay Healthy

Will the seasonal flu shot protect me against pandemic influenza?

• No, it won't protect you against pandemic influenza. But flu shots can help you to stay healthy.
• Get a flu shot to help protect yourself from seasonal flu.
• Get a pneumonia shot to prevent secondary infection if you are over the age of 65 or have a chronic illness such as diabetes or asthma. For specific guidelines, talk to your health care provider or call the Centers for Disease Control and Prevention (CDC) Hotline at 1-800-232-4636.
• Make sure that your family's immunizations are up-to-date.

Take common-sense steps to limit the spread of germs. Make good hygiene a habit.

• Wash hands frequently with soap and water.
• Cover your mouth and nose with a tissue when you cough or sneeze.
• Put used tissues in a waste basket.
• Cough or sneeze into your upper sleeve if you don?t have a tissue.
• Clean your hands after coughing or sneezing. Use soap and water or an alcohol-based hand cleaner.
• Stay at home if you are sick.

It is always a good idea to practice good health habits.

• Eat a balanced diet. Be sure to eat a variety of foods, including plenty of vegetables, fruits, and whole grain products. Also include low-fat dairy products, lean meats, poultry, fish, and beans. Drink lots of water and go easy on salt, sugar, alcohol, and saturated fat.
• Exercise on a regular basis and get plenty of rest.

Get Informed

Knowing the facts is the best preparation. Identify sources you can count on for reliable information. If a pandemic occurs, having accurate and reliable information will be critical.

• Reliable, accurate, and timely information is available at www.pandemicflu.gov.
• Another source for information on pandemic influenza is the Centers for Disease Control and Prevention (CDC) Hotline at: 1-800-CDC-INFO (1-800-232-4636). This line is available in English and Spanish, 24 hours a day, 7 days a week. TTY: 1-888-232-6348. Questions can be e-mailed to inquiry@cdc.gov.
• Look for information on your local and state government Web sites. Links are available to each state department of public health at www.cdc.gov/other.html#states.
• Listen to local and national radio, watch news reports on television, and read your newspaper and other sources of printed and Web-based information.
• Talk to your local health care providers and public health officials.

As you begin your individual or family planning, you may want to review your state's planning efforts and those of your local public health and emergency preparedness officials. Many of the state plans and other planning information can be found at pandemicflu.gov/plan/tab2.html.

Phases of an influenza pandemic

The World Health Organizationannounces the current phase of the pandemic alert here.

See "Assessing the pandemic threat" at [15]. WHO published a first edition of the Global Influenza Preparedness Plan in 1999, and updated it in April 2005. See [16]and [17]which define the responsibilities of WHO and national authorities in case of an influenza pandemic. This is the first time a pandemic has been anticipated and is being prepared for.

The aims of such plans are, broadly speaking, the following:

• Before a pandemic, attempt to prevent it and prepare for it in case prevention fails.
• If a pandemic does occur, to slow its spread and allow societies to function as normally as possible.

The World Health Organization (WHO) has developed a global influenza preparedness plan, which defines the stages of a pandemic, outlines WHO's role and makes recommendations for national measures before and during a pandemic.

Investigations of small clusters of cases are currently ongoing in southeast Asia, particularly Vietnam, to rule out limited human-to-human spread (which would signify Phase 4). The phases are defined as:

Interpandemic period

Phase 1: Low risk No new influenza virus subtypes dangerous to humans detected in humans or animals.

Phase 2: New virus A new circulating animal influenza virus subtype poses a substantial risk of human disease but no new influenza virus subtypes have been detected in humans.

Pandemic alert period

Phase 3: Self limiting Human infection(s) with a new subtype, but no human-to-human spread, or at most rare instances of spread to a close contact. Even without human intervention it would be self limiting among humans.

Phase 4: Person to person: Small cluster(s) with limited human-to-human transmission but spread is highly localized, suggesting that the virus is not well adapted to humans. An epidemic is possible but has not yet happened.

Phase 5: Epidemic: Larger cluster(s) but human-to-human spread still localized, suggesting that the virus is becoming increasingly well adapted to humans, but may not yet be fully transmissible (substantial pandemic risk).

Pandemic period

Phase 6: Pandemic: increased and sustained transmission in general population.

Notes

The distinction between phase 1 and phase 2 is based on the risk of human infection or disease resulting from circulating strains in animals. The distinction is based on various factors and their relative importance according to current scientific knowledge. Factors may include pathogenicity in animals and humans, occurrence in domesticated animals and livestock or only in wildlife, whether the virus is enzootic or epizootic, geographically localized or widespread, and/or other scientific parameters.

The distinction between phase 3, phase 4 and phase 5 is based on an assessment of the risk of a pandemic. Various factors and their relative importance according to current scientific knowledge may be considered. Factors may include rate of transmission, geographical location and spread, severity of illness, presence of genes from human strains (if derived from an animal strain), and/or other scientific parameters.

The pandemic stage 6 may be marked by two or more waves. For example, the initial wave of the Spanish Influenza pandemic in the spring of 1918 was so mild in its effects that it received the dismissive nickname of the "three day flu." But when the second wave hit North America a few months later in the summer of 1918, it was lethal. Apparently in the interim the novel H1N1 pandemic strain had added the gene or genes that made the final wave a killer. Perhaps the effects of the lethal second wave would have been even more devastating if the innocuous first wave had not already passed through the population, leaving in its wake at least some immune response to the surface antigens presented by the H1N1 in both waves.

CIDRAP provides a thoroughgoing overview, Pandemic Influenza,which has its roots in materials from the U.S. HHS National Vaccine Program Office. CIDRAP's overview originally set forth a model listing five numbered stages for the pandemic itself, preceded by four additional pre-pandemic stages, each numbered as zero, that overlapped the WHO's first five stages of a pandemic. CIDRAP's overview has since adopted the WHO's 6-stage model.

Preparations for a potential influenza pandemic

"[T]he United Statesis collaborating closely with eight international organizations, including the World Health Organization(WHO), the Food and Agriculture Organization of the United Nations(FAO), the World Organization for Animal Health(OIE), and 88 foreign governments to address the situation through planning, greater monitoring, and full transparency in reporting and investigating avian influenzaoccurrences. The United States and these international partners have led global efforts to encourage countries to heighten surveillance for outbreaks in poultry and significant numbers of deaths in migratory birds and to rapidly introduce containment measures. The U.S. Agency for International Development(USAID) and the U.S. Department of State, the U.S. Department of Health and Human Services(HHS), and Agriculture(USDA) are coordinating future international response measures on behalf of the White House with departments and agencies across the federal government." [18]

Together steps are being taken to "minimize the risk of further spread in animal populations", "reduce the risk of human infections", and "further support pandemic planning and preparedness". [19]

Ongoing detailed mutually coordinated onsite surveillance and analysis of human and animal H5N1avian flu outbreaks are being conducted and reported by the USGSNational Wildlife Health Center, the Centers for Disease Control and Prevention, the World Health Organization, the European Commission, the National Influenza Centers, and others. [20]

United Nations

In September 2005, David Nabarro, a lead UN health official warned that a bird flu outbreak could happen anytime and had the potential to kill 5-150 million people. [21]

United States

"[E]fforts by the federal government to prepare for pandemic influenza at the national level include a $100 million DHHS initiative in 2003to build U.S. vaccineproduction. Several agencies within Department of Health and Human Services(DHHS) ? including the Office of the Secretary, the Food and Drug Administration(FDA), CDC, and the National Institute of Allergy and Infectious Diseases(NIAID) ? are in the process of working with vaccine manufacturers to facilitate production of pilot vaccine lots for both H5N1and H9N2 strains as well as contracting for the manufacturing of 2 million doses of an H5N1 vaccine. This H5N1 vaccine production will provide a critical pilot test of the pandemic vaccine system; it will also be used for clinical trials to evaluate dose and immunogenicity and can provide initial vaccine for early use in the event of an emerging pandemic." [22]

On August 26, 2004, Secretary of Health and Human Services, Tommy Thompsonreleased a draft Pandemic Influenza Response and Preparedness Plan [23], which outlined a coordinated national strategy to prepare for and respond to an influenza pandemic. Public comments were accepted for 60 days.

In a speech before the United Nations General Assembly on September 14, 2004, President George W. Bush announced the creation of the International Partnership on Avian and Pandemic Influenza. The Partnership brings together nations and international organizations to improve global readiness by:

• elevating the issue on national agendas;
• coordinating efforts among donor and affected nations;
• mobilizing and leveraging resources;
• increasing transparency in disease reporting and surveillance; and
• building capacity to identify, contain and respond to a pandemic influenza.

On October 5, 2005, Democratic Senators Harry Reid, Evan Bayh, Dick Durbin, Ted Kennedy, Barack Obama, and Tom Harkinintroduced the Pandemic Preparedness and Response Actas a proposal to deal with a possible outbreak. ([24])

On October 27, 2005, the Department of Health and Human Serviced awarded a $62.5 million contract to Chiron Corporation to manufacture an avian influenza vaccine designed to protect against the H5N1 influenza virus strain. This followed a previous awarded $100 million contract to sanofi pasteur, the vaccines business of the sanofi-aventis Group, for avian flu vaccine.

On November 1, 2005 President Bush unveiled the National Strategy To Safeguard Against The Danger of Pandemic Influenza [25]. He also submited a request to Congress for $7.1 billion to begin implementing the plan. The request includes $251 million to detect and contain outbreaks before they spread around the world; $2.8 billion to accelerate development of cell-culture technology; $800 million for development of new treatments and vaccines; $1.519 billion for the Departments of Health and Human Services (HHS) and Defense to purchase influenza vaccines; $1.029 billion to stockpile antiviral medications; and $644 million to ensure that all levels of government are prepared to respond to a pandemic outbreak.

In October 2005, President Bushurged bird flu vaccine manufacturers to increase their production. [26].

Preparedness plans

• United States Draft 2004Final 2005
• European Commission

Further reading

• Nature Magazine: Avian flu special: The flu pandemic: were we ready?Fictional account of flu epidemic from Nature magazine
• Worldwide Disasters - Pandemics
• Pandemic Influenza Risk Communication: The Teachable Moment, by Sandman and Lanard
• Latest Bird Flu and global pandemic advice
• Information about the next pandemic
• World Health Organisation pandemic alert page
• Pandemic Plan blog- Practical commentary explaining why you should prepare for a possible influenza pandemic; plus, creative insights about how to prepare (and what others are doing).

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Influenza+pandemic Wikipedia article Influenza pandemic.