Corporate and Foundation Relations

Q&A ON AVIAN FLU

A wide range of questions were generated by the audience of the Harvard School of Public Health’s Web seminar "Bird Flu: Public Health and Pandemics." These questions, and their answers, appear below, grouped into seven broad areas for easier reading. View the recording.

Why avian flu is coming into prominence now?
Avian flu transmission questions
Controlling a global epidemic
What individuals should do to prepare
What businesses and local governments should do to prepare
What healthcare organizations should do to prepare
Additional resources

Why avian flu is coming into prominence now?

Q: The threat of pandemic flu is not new, and even H5N1 concern dates back to 1997. What caused the intense public focus to happen now?
A: The threat of pandemic flu did not receive as much attention as it deserves until H5N1 emerged. While the first 1997 H5N1 avian flu outbreak was relatively limited and quickly controlled, the current outbreak has been ongoing since 2003 and is concerning because it causes such severe illness and has spread so rapidly in a relatively short period of time.

Q: Has the H5 strain of flu ever circulated in annual influenza?
A: No. The major epidemic strains in humans have been H1, 2 or 3. H5 has been seen in birds in the past. The worry is that it if it learned how to jump efficiently among humans it could cause a new pandemic.

Q: What does research tell us to help explain why H5N1 is so virulent and why it is currently unable to transmit easily from human to human?
A: We don't know precisely what determines virulence or how to predict how virulent a virus will be. Avian flu is currently unable to efficiently transmit between humans. However, this could change if the virus were able to join its genetic components with those of a human flu strain. This "reassortment" process could happen in people or in the cells of pigs, which are able to be infected by both avian and human flu strains. Additionally, the virus is currently believed to be most efficient in infecting human cells in the lower respiratory tract and intestines. A spontaneous mutation in its H protein could allow it to attach to cells in the upper respiratory tract where it could be more easily spread through coughs, sneezes and nasal mucous.

Q: Might a genetic analysis of the virus be possible and would it help determine the risk of it evolving to become infectious to humans?
A: Genetic analysis is constantly being done. In the most recent clusters in Indonesia the virus was genetically analyzed to see if it was different from previous strains of H5N1, or if had mutated in a way that would make it more transmissible from person to person. World Health Organization authorities were actually reassured by the fact that the genetic makeup of the virus had not changed in comparison to previous strains of the virus.

Q: Just as the virus must mutate to become easily transmissible between humans, could it mutate to become less virulent?
A: All of the pandemic strains in history have been less virulent than the current H5N1 virus, which leads us to believe that as a virus undergoes the necessary genetic changes to be passed easily from person to person, it must lose some of its virulence. The 1918 pandemic strain had a mortality of 2-5% globally, so we expect that if H5N1 became a pandemic strain, the mortality associated with the virus would be less than the current 50% mortality. However, there's no way to predict what the mortality rate would be.

Avian flu transmission questions

Q: How long does the avian flu virus live on surfaces?
A: H5N1 can live on surfaces for up to 48 hours. In general, the greatest dangers for infection by a flu virus are (a) being within three feet of someone who has been exposed and is spreading infection via droplets generated when coughing or sneezing, or (b) by exposure to droplets from coughing or sneezing that land on hard, non-porous surfaces.

Q: Is there a particular age group that is more susceptible to H5N1?
A: The hardest hit age group with H5N1 is age 6-30. Of the three pandemics of the 20 th century, only the 1918 pandemic was similar, disproportionately killing the young and healthy. The 1957 and 1968 strains mostly affected the elderly and infant populations the way seasonal influenza does.

Q: Why is the infection only predicted to affect 30% of the population if it grows to pandemic proportions?
A: Some people won't be exposed. Others may have a sub-clinical infection, meaning they are infected but they aren't showing any significant symptoms. It's hard to know exactly what will enable some people to become infected but show no signs of illness while others infected develop full-blown disease.

Q: Does the possibility of pandemic flu warrant the current media scare tactics, such as the television movie "Fatal Contact: Bird Flu in America"?
A: We know that a pandemic is likely to occur because on average, there have been three per century in recorded history. The last one occurred in 1968, so we are due for another one. Pandemic flu strains range from relatively mild (1968), to very severe (1918). Even in a mild 1968-type pandemic, there would probably be three times as many deaths from influenza as we currently have (the Centers for Disease Control estimates 36,000 annual deaths from flu). That would likely cause concern, if not some minor disruptions in society. A major pandemic on the order of 1918 would cause very significant disruptions in society, even for people who did not get sick, due to interruptions in supply chains and interruptions in business, schools and public functions. Therefore, it is worthwhile to pay attention to the possibility of a pandemic and to plan for it. However, using scare tactics to get people's attention is not useful.

In regards to the current strain of avian flu, the scientific community is split on how concerned we should be. One camp says that it's only a matter of time before the virus mutates and becomes easily transmissible from human-to-human. The other says that if it hasn't happened yet this may be because the virus cannot tolerate mutations required to become easily transmissible among humans. (There have been 128 deaths from 225 reported human cases worldwide, and reports of the H5N1 virus in birds or animals in 53 countries, as of June 6, 2006. See the World Health Organization for the latest statistics.) But we don't know, so we have to be prepared.

Q: How much warning will we have that the virus has mutated to efficiently transmit human to human? How much time is likely to lapse between when this mutation occurs and public health officials realize that it has occurred?
A: The hope is that we will pick up one of the early cases, but the longer it takes to identify rapid human to human transmission, the harder it will be for us to act. The three pandemics in the 20 th century occurred before the international travel era and they still passed around the globe in a matter of months. It could only be a matter of weeks between the time the virus begins to transmit between humans and its arrival on our shores. But there might be a bit more time than we think. Encouragingly, for most of the major pandemic waves, there seems to be an earlier, milder wave that precedes it. If we are vigilant, we could get a six-month warning of an upcoming pandemic.

Controlling a global epidemic

Q: It has been speculated that the pandemic would likely be greatly assisted by air transportation. What are the recommendations for air transportation? Would a "no fly" period be effective in stopping the pandemic? In the worse case scenario, would the US and other nations have to completely close down their borders?
A: It's difficult to prevent people who are in close contact for a long period of time from being exposed to aerosol droplets. Airlines can screen for people who appear to have a fever or cough, but people can transmit the virus for up to 2 days before they have symptoms. Airplane seats can be wiped down to get surface-attached virus, but the virus can stick in crevices and in fabrics. The recirculating air is something of a problem, but most of the air is filtered through a HEPA filter on major airliners.

Closing our borders is not realistic. It has a limited effect on public health, and can have a devastating effect on disaster response and the economy. Eighty percent of medications are manufactured, in part, overseas or have an overseas ingredient. Closing the border would limit access to these drugs and other medical supplies and greatly inhibit our ability to respond to a pandemic.

Q: If an outbreak of pandemic flu appeared in China, for example, what course of action would be open to Americans visiting there?
A: It's unclear. It is possible that Americans traveling abroad in such a circumstance would be allowed to come back to the United States only with a mandatory waiting period in some neutral or quarantined location to make sure they weren't infected. Or health authorities in China or any other affected nation could impose quarantine and prohibit travel away from an affected area. American citizens always have representation through the embassy or consulate in the country in which they're traveling, and can request services from that consulate. Almost always, they would receive their initial health care from the local health care institutions. There are international medical evacuation programs and services that are generally very expensive and again, may or may not be able to actually get you a person out if there were a state-imposed travel restriction.

Q: It was reported that the UN has noted a drop in cases in China and Vietnam. Is there any reason to think this means something?
A: When that report came out, people speculated that the countries' control measures, such as culling large bird populations and educating some of their populations, had been effective. These reports were followed by a new increase in the number of cases in Indonesia. So while the decrease in China and Vietnam may mean that public health interventions have been effective, it likely does not mean that the virus is burning itself out and is going away any time soon.

What individuals should do to prepare

Q: What can we do to prepare our families?
A: Try to get the current seasonal flu shot. People should also get the pneumococcal vaccination, particularly older people. It helps prevent bacterial pneumonia, which caused a large percentage of the 1918 deaths. Stock up on provisions like bottled water, canned goods and chronic medications so if a pandemic occurs you can stay at home if necessary to limit exposure to others. Washing hands frequently will be extremely important to prevent spread of the disease.

Q: What do you currently recommend regarding antivirals? What about stockpiling penicillin?
A: The best antiviral that we know of so far is oseltamivir, which is marketed under the name Tamiflu. It can be administered in pill form and it seems to be the most effective. There is some recent data that says that amantadine and ramantadine, two of the oldest antivirals, may actually be useful. They would be best in a sense because we have the most of them stockpiled already, and they are the lowest cost. We have less of the inhaled neuraminidase inhibitor Relenza (zanamivir). It's also harder to administer because it is inhaled rather than taken by mouth.

However, the recommendation for private individuals and corporations is not to stockpile antivirals or antibiotics. Antivirals could buy some time in a pandemic, but they won't work if they are overused. Resistance may develop prematurely.
Additionally, the secondary infection that contributed to mortality in past pandemics is pneumococcal, strep pneumonia. Many strains of strep pneumonia are resistant to penicillin, so penicillin as an antibiotic probably may not be helpful.

Q: Are there masks or other devices to limit exposure?
A: The Institute of Medicine recently concluded that there's not enough scientific evidence to recommend mask use by the public in a pandemic. It's not been proven that they protect the wearer or that they cut down on disease transmission rates if the person wearing the mask is infected. By the same token, they have not been proven to be ineffective, so if people want to use masks, it's probably ok. Paper surgical masks are preferable to N-95 respirators, which can give a false sense of security. N-95 masks that are not properly fit-tested can leave unprotected gaps between the mask and your face. This impairs the mask's effectiveness. They also make the wearer work harder to breathe, which can be dangerous to people with chronic lung diseases like asthma and emphysema who have not been appropriately trained. Also, the masks break down after a period of time. When the wearer breathes through them for a number of hours with moisture, their filtering effectiveness is lost. Wearers may think they are protected when they are not.

Q: We have a small backyard flock of chickens that live in the same barn as our barn swallows. We also have a small pond that attracts migrating ducks and herons. At what point should we be concerned about our chickens?
A: In general, people who have chickens should keep them indoors and covered when there is H5N1 in the area. Birds migrating overhead can excrete the virus in their feces and infect other birds. But before there is confirmed H5N1 in North America there's not really anything you can do for prevention. Bird vaccines are being used commercially for large flocks, but right now they're not being offered to anyone with home poultry.

Cooked poultry poses no health risk at all. When handling raw poultry that's been commercially prepared, washing hands should be sufficient to protect against infection, but we don't know for sure. Handling freshly killed birds, especially their feathers or their skin, could pose a risk.

What businesses and local governments should do to prepare

Q: Can you recommend a response plan outline?
A: The U.S. federal government plan is good. See www.pandemicflu.gov for checklists for individuals and businesses.

Q: How would one know if they're infected, or how would an employer best screen for employees that may be infectious? What is the incubation period? Is it symptomatic or asymptomatic? Don't most flu infections have a large number of cases that are never clinically identified or diagnosed? If so, how can any containment protocol be effective?
A: There's no effective method of screening because of the unique characteristics of the virus. People can transmit the virus before they exhibit any symptoms. Businesses should encourage maintenance of personal health. That includes staying at home if you think you're sick or think you have been exposed. At-risk persons should be encouraged to stay at home for 5-10 days.

Q: How can we protect water supplies in reservoirs? Food supplies?
A: H5N1 is not a waterborne illness; therefore the water supplies should not be at substantial risk. See the WHO Web site for information on food safety issues around avian influenza.

Q: Is there a risk that overreaction will dilute ongoing planning efforts over the long term?
A: There's a risk that too much hype about any one threat that doesn't immediately come to pass decreases the credibility of efforts for preparedness. If people get very excited about a pandemic and it doesn't come for the next few years — which is actually very probable — it's possible that future efforts to prepare for infectious disease pandemics will be viewed with a jaundiced eye. And so it's more important to prepare for the long term, as opposed to preparing for what's most in the news right now, so that the public keeps it's faith in the preparedness effort and planners aren't constantly shifting from one current media-hyped potential disaster to the next.

Q: How do we manage panic and irrational behavior if a pandemic does occur?
A: Fear is certainly understandable in the setting of a pandemic. Generally speaking, education is the best weapon — letting people know what the real threats are and what they can do to protect themselves and minimize their exposure. Good, consistent risk communications where messages do not conflict with one another and are easily understood by the public are probably our best weapons.

What healthcare organizations should do to prepare

Q: Should hospitals stockpile antivirals for their health care workers?
A: Hospitals and public health authorities should have some supply of antiviral medications on hand in order to be able to respond quickly to early cases of suspected pandemic strains of influenza. This will allow them to treat frontline health workers in hopes that those most needed to treat others can limit their likelihood of developing the flu. Individual hospitals and local and state public health officials should work together to make sure that whatever stockpiles of medicines exist are used most effectively for the community since this really will be a community-wide illness or threat.

Q: What are your views on the potential effectiveness of priming vaccine strategies in helping to reduce the risk or severity of a pandemic?
A: If the question is vaccinating humans against H5N1 before an H5N1 strain turns into a pandemic just so that our collective immune systems have seen the H5 and the N1 antigens ahead of time, there really is no data to suggest how that might change a person's immune response to a subsequent strain of H5N1 that became a pandemic strain. In other words, just having immunity to H5N1 may or may not be helpful in terms of mitigating the mortality of a particular H5N1 pandemic strain. We just don't know.

Q: Is the vaccine made from reverse genetics in clinical trial yet? What are your views on the use of vaccines made from reverse genetics?
A: The current vaccine that is being stockpiled at the federal level is being made the standard way, using fertilized chicken eggs in which the virus has been incubated. There are trials underway to attempt to rapidly create vaccines by genetically engineering a vaccine, but those have not yet been reported. So while that is a promising technology, it is not clear how soon we could put it into use for the development of a vaccine.

Q: Are "negative pressure" waiting rooms in hospitals worthwhile?
These rooms are often used to quarantine patients with contagious, airborne diseases. They are maintained at a lower pressure than their surroundings, causing air to flow in from the outside when a door or window is opened. Air is exhausted directly outside or through a HEPA filter. HEPA stands for high efficiency particulate air. These filters are designed to remove 99.97% of airborne particles that are 0.3 micrometers or larger, including dust, pollen, mold and bacteria.
A: It is unclear how much this would be helpful in the event of a pandemic flu. The problem is that in a negative pressure waiting room, people are still likely to be within three feet of each other, sneezing and touching surfaces. People can still transmit the virus even when the air is removed rapidly from the waiting room and filtered and exhausted. It would probably cut down somewhat on transmission rates, but given that we know that droplets are a component to influenza infection, people being closer than three feet from each other means that transmission is still possible.

Q: Are HEPA filters effective against airborne recirculation of H5N1?
A: HEPA filters do filter circulating virus; however, it is not thought that the primary mode of transmission of the influenza virus is by airborne transmission. The primary mode is thought to be through droplet transmission within three feet of the source, or by droplets that land on hard, non-porous surfaces; therefore, HEPA filters may decrease transmission rates somewhat, but do not affect the majority of influenza transmission.

Sources

"Bird Flu: Public Health and Pandemics" Web seminar with Dean Barry Bloom and Dr. Paul Biddinger (View the recording); additional interview with Dr. Biddinger.

"Flu Catchers." By Thea Singer. Harvard Public Health Review. Winter 2006.

"Why Bird Flu Doesn't Spread Between Humans." By Richard Ingham. News in Science. March 23, 2006.

Additional resources

World Health Organization updates on avian flu cases.

Health and Human Services pandemic flu resources, including checklists for individuals and businesses.

Centers for Disease Control and Prevention avian flu resources.

New Zealand government pandemic flu site. Contains detailed individual and business planning resources.

The Flu Wiki, a collaborative site with a variety of avian flu articles and links.