Flu Season

William L. Atkinson and William W. Thompson, Ph.D. of the Centers for Disease Control and Prevention (CDC) were online Thursday, Nov. 3, at 3 p.m. ET to answer your questions about flu season and to discuss the statistics of flu deaths and the effectiveness of vaccines.

Atkinson, medical epidemiologist at the National Immunization Program of the Centers for the CDC, has been responsible for the development and implementation of immunization education and training materials for vaccine providers since 1995.

Thompson is epidemiologist with the Immunization Safety Office of the CDC. In 1998, he was hired by the CDC Influenza Branch to develop innovative statistical models for assessing influenza-associated morbidity and mortality. In 2000, Thompson took a position as an epidemiology in the Immunization Safety Office. His recent research has focused on studies examining associations between childhood vaccines and subsequent neuropsychological outcomes.

NOTE: Steven Woloshin and Lisa Schwartz, physician-researchers in the VA Outcomes Group, were online Tuesday, Oct. 25, at 11:30 a.m. ET to discuss statistics of flu deaths and the effectiveness of vaccines based on their research and their article that ran in The Washington Post on Tuesday, Oct. 25.

Read More:

A Shot of Fear (Post, Oct. 25) | Discussion Transcript (Oct. 25)

From The Post: Flu Basics

A transcript follows.

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Washington, D.C.: Why is the flu shot system plagued with distribution problems every year? It's hard enough to convince people to get immunized; making it extremely difficult to find a flu shot definitely has a negative impact. We will have a newborn during flu season, so I am urging all family and friends to get the shot this year. But they will give up if it's too hard. As a pregnant woman, I spent hours finding a thimerosal-free shot and none were available before the October 24th high-risk cutoff. How can we improve the system and make it easier for people to get the vaccine each year?

William L. Atkinson: Production of influenza vaccine is extremely complicated. It involves multiple manufacturers, the Food and Drug Administration, CDC, the World Health Organization, and millions of chickens (to provide the millions of eggs needed to grow the virus). The vaccine basically is produced from scratch each year. It would be difficult to streamline production given current technology. There will always be uncertainties and problems that were not anticipated. Our goal is to provide enough safe and effective vaccine for everyone who wants a dose and most years that happens. We will continue to work with all parties to find ways to make the system work better. Consumers should try to be patient, and remember that influenza season doesn't usually start in the U.S. until December, so it is not necessary to always get your vaccine in October. You can still be effectively vaccinated in November, December, or even later.

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Washington, D.C.: Today, American University's law school was scheduled to provide flu shots to students, but had to cancel the afternoon session because the shipment of vaccine had not come in. An article in today's Post seems to indicate that this is the norm in the area this Fall. Is there enough vaccine this year? If so, what is the cause of these delays in delivery?

washingtonpost.com: Flu Plan Counts on Public Cooperation (Post, Nov. 3)

Unknowns Pose A Challenge for Preparedness Plan (Post, Nov. 3)

William L. Atkinson: We expect there to be as much influenza vaccine this year as has ever been available in previous years - something like 80 million doses. No one can guarantee when all the vaccine will arrive. We would prefer it all to be available in October, but the reality is that 100% distribution often does not happen until November or December. Organizations that plan influenza vaccine clinics should be aware of this and plan accordingly - wait until mid November to have those big clinics when vaccine is more likely to be available.

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Reston, Va.: Why don't more employers offer flu-shot clinics on site? It would reduce absenteeism and take away a hassle for employees, even if it were voluntary and paid for by employees.

William L. Atkinson: We agree that getting annual influenza vaccination should be as easy and convenient as possible. Many employers do provide this as a service to their employees. Perhaps you should discuss this with the employee health department of your company.

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Pittsburgh, Pa.: It appears there is national shortage of vaccine at this time. The word had been that plenty of vaccine would be available in November, but November is here and more than reassurance is required. What is the status of Chiron's vaccine and will more than the meager percentage that has been shipped be available. We are postponing plans for vaccine for old frail residents in nursing homes and the homebound in our community. It is time for the CDC to acknowledge the uncertainty and provide direction that will enable us to plan. And if flu shots were not going to be available until Nov and Dec. the CDC should have engaged in a public relations campaign to inform the public.

William L. Atkinson: We do not believe there will be a shortage of influenza vaccine this year. CDC continually acknowledges the uncertainty of the influenza vaccine supply at any given point in time. We expect plenty of vaccine to be available this year, but it may be the end of November before it is all distributed. Lots of Chiron vaccine are being approved by FDA and shipped now.

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Seattle, Wash.: Given that flu victims in the pandemic of 1918 treated by Homeopathic physicians had up to a 90 percent less chance of dying than those treated by allopaths, why is there no mention of this in the grand scheme to manage the next pandemic?

William L. Atkinson: I have seen no evidence of this claim.

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New York, N.Y.: If a person gets a flu shot, are they more susceptible to other ailments?

William L. Atkinson: No, influenza vaccine does not increase susceptibility to any other infection or condition.

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Anonymous: In a letter to the editor printed in the Wall Street Journal earlier this week (I hope it's ok to mention the competition) a physician wrote that it promotes unreasonable fear to keep comparing the prospect of a bird flu epidemic to the 1918 flu pandemic (100 million dead,etc.). He said that treatment of flu in 1918 basically consisted of bed rest. There were no antibiotics to fight bacterial pneumonias, which he said is the primary cause of death in flu cases, and even IVs to replace lost fluids weren't commonly used. His point was that even if you actually contract bird flu, which at this point seems to have been found only among a handful of humans that live with chickens, modern medical care will make death a very unlikely outcome. Obviously, I'd like to believe this guy. Is he right?

William L. Atkinson: To date about half of people who have been confirmed as having H5 (avian) influenza have died. This fatality rate is probably an over-estimate since we don't know how many infections have occurred that have not been reported. It is true that we have many more tools available for medical treatment of severe influenza or its complications. We can only guess what the impact of a 1918-like influenza virus might be today.

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Oklahoma City, Okla.: Thank you for taking our questions.

Everyone is getting lathered up over a virus deadly only to birds and Asian farmers who live in filth with their sick birds and pigs.

A word please on which strains of flu of the human to human variety are most likely to make us sick this flu season, and are they in the current vaccine?

William L. Atkinson: The three strains of influenza virus most likely to affect the US this year are called H3N2, H1N1, and B. Representative viruses from these three strains have been selected for this year's vaccine. Most years the strains selected for the vaccine match those that circulate in the population. It is very early in the influenza season and we do not know yet what the dominant virus will be in the US. You can monitor this as the season progresses on CDC's influenza website at www.cdc.gov/flu

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Central Virginia: Gentlemen,

The massive increase in public health and longevity over the last few centuries has been associated not with increased medical care but with improved nutrition. A well-nourished body tends have a more robust immune system, and so is more effective in resisting disease.

I believe that the people who have died of bird flu so far have been near the poverty line -- small farmers and so on, in Asia, who probably did not have the physical reserves of a well-fed Westerner.

This being the case, do you think that our currently hyper-"healthy" population would be able to resist an onslaught of flu more effectively than individuals in the Third World?

I know that we have a substantial population of high-risk individuals -- the fragile elderly, people who are HIV+, transplantees, and so on. But what about the general populace?

Thank you.

William L. Atkinson: It is likely that well-nourished healthy people might be better able to tolerate an infection with influenza virus. We cannot anticipate how the next pandemic influenza virus will affect the general population. Pandemics in the past have ranged from very severe (1918, 1957) to mild (1968). The severity will depend on the virus. Being healthy is good, but will not absolutely assure a reduction in morbidity or mortality. Most of the deaths from influenza typically occur in the older segment of the population (65 years and older), particularly those with concurrent underlying illnesses.

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Rockville, Md.: I read with some dismay the triage plan for limited pandemic flu vaccine. Over-65 as a priority group, really? Without trying to seem cynical, or ageist (I'm not that much younger), is this AARP at work?

William W. Thompson, Ph.D.: You need not believe that AARP is at work. More than 90% of the influenza-associated deaths that occur in the US annually occur among persons aged 65 years and older. There are also a substantial number of hospitalizations that occur in this age group.

William L. Atkinson: I agree that prevention of death is an important goal in any influenza season, or in the event of a pandemic. To do this we will have to target our vaccine to those most likely to die, people 65 years and older.

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Arlington, Va.: So are there flu vaccine shortages or not? The government keeps saying there are not, but all indications are that vaccine supply is severely curtailed at the moment. Clinics are being cancelled at the last minute. Why is there not enough vaccine?

William L. Atkinson: We believe there will be plenty of vaccine, but that it will arrive a little later than we would like. Clinics that have been cancelled were probably planned for too early a date, given that we have had delays during several of the past seasons. We expect about 80 million doses to have been distributed by the end of November, most of which has already been shipped.

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Newtown, Conn.: As a former employee of Public Health, I am deeply concerned of having enough qualified personnel to handle a flu pandemic. So many excellent employees have left this field and I have found a lack of dedication with younger employees.

Your comments would be deeply appreciated.

William L. Atkinson: The size of the public health workforce has declined in recent years, but not necessarily because of lack of dedication to the work. All plans for a response to pandemic influenza, or any other public health emergency must be based on available resources. Because the core public health workforce is smaller, planners need to think about supplementing them from other sources, such as volunteers.

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Washington, D.C.: How long do flu viruses live on surfaces (doorknobs, clothing,...)? What household products will kill a flu virus?

William L. Atkinson: Influenza viruses may survive up to 2 hours on inanimate surfaces. One of the most important things a person can do to reduce their chance of influenza and other illnesses is to WASH THEIR HANDS frequently. Household cleaning products can inactivate the virus, but you can't sterilize your entire environment. WASH YOUR HANDS!

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Baarn The Netherlands: How do you organize the priorities in the USA? In the Netherlands one discusses to issue a priority list for accepting/rejecting people who are infected by the virus in case of a large scale pandemia. I disagree with with such principles and am of the opinion like in France and Scandinavia to set up priorities in the non flu infected sector first to make a maximum of personnel free to take care of the infected people first. Moreover bed capacities and capacity in lung machinery has to be installed in unused buildings, e.g. former military buildings.

What is your approach in the USA?

William L. Atkinson: This is a very complicated question. I suggest you review the U.S. pandemic influenza plan which is now available on the Department of Health and Human Services Web site at

http://www.hhs.gov/pandemicflu/plan/

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Seattle, Wash: With regard to Homeopathic treatment for flu, a good review and my source is The NewEngland Journal of Homeopathy, Spring/Summer 1998, Vol.7 No.1 "Influenza 1918", by Julian Winston. To whom at CDC should this data be sent?

William L. Atkinson: Homeopathic treatment, by definition, contains no active ingredient. If people who received this "treatment" in 1918 were found to have improved survival, it was most likely because of bias in the selection of patients, or selective reporting, not because the treatment was effective. I will look at the article if it is available in the CDC library (which I doubt) or online somewhere.

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Deep Creek Lake, Md.: Why is it called H5N1? Where does that come from?

William L. Atkinson: The "H" stands for hemagglutinin, and the "N" stands for neuraminadase. These are two molecules on the surface of influenza virus that are important in the virus infecting its host, and a particular strain of influenza virus can be identified by what type of H and N is on its surface.

H and N molecules can be grouped based on their chemical composition. Something like 16 different types of H and 9 types of N are known to exist. Only 3 types of H and 2 types of N have ever been found on human influenza viruses. Other animals are infected with different H's and N's. H5N1 is a type of influenza virus that until 1997 was thought only to infect birds (hence "bird" or "avian" influenza). We now know that it can sometimes be transmitted from a bird to a human. Humans are most commonly infected with influenza types H3N2 and H1N1.

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New York,, N.Y.: If one had the flu during the 1957-58 epidemic, would one have any extra immunities, or perhaps more susceptibility, to the flu?

William L. Atkinson: The 1957 influenza pandemic was caused by so-called "Asian" influenza, also known as H2N2. For reasons we (or at least I) don't understand, H2N2 virus disappeared in 1968 and was replaced by type H3N2 virus. H3N2 circulates throughout the world even now.

If a person were infected with H2N2 virus it is possible that the person could have some residual immunity to other influenza viruses that have the N2 molecule on the surface. Practically this is not likely to benefit the person very much, because even infection with an H3N2 strain of virus from a prior year doesn't provide much protection from the H3N2 virus that may circulate this year.

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Front Royal, Va.: I've started taking zinc, vitamin C, and those fizzy tablets that are supposed to ward off colds and germs while flying or in classrooms or other crowds. Will these protect me from getting ill from the flu? I give these to my children too -- are there age differences in folks susceptibility to getting sick or how well these aids work to prevent flu?

William L. Atkinson: These products will not protect you from influenza. You should save your money, get a dose of influenza vaccine, and make it a habit to wash your hands frequently.

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washingtonpost.com: On Tuesday, Oct. 25, The Washington Post published an article written by Steven Woloshin, Lisa M. Schwartz and H. Gilbert Welch --- three physician-researchers in the VA Outcomes Group -- that examined flu death risk and the benefit of vaccine based on their research. The article speaks to exaggerated risk and benefit (Read the full article: A Shot of Fear ).

The first paragraph of the article reads:

"For years, the public health community has used fear as one strategy to promote the flu vaccine. A vaccination poster distributed by the U.S. Centers for Disease Control and Prevention (CDC), for example, emphasizes that '36,000 Americans die of flu-related illnesses each year,' implying that the vaccine could prevent many of these deaths." (Read more.)

How would you respond to this article, and how was the number "36,000" arrived at?

William W. Thompson, Ph.D.: The estimate of 36,000 influenza-associated deaths is based on comparisons of mortality rates during periods when influenza viruses are circulating and when influenza viruses are not circulating. It is a conservative estimate based only on respiratory and circulatory deaths. The vaccine is not 100% effective in reducing influenza-associated deaths so the vaccine would definitely not prevent all 36,000 deaths. Current estimates of vaccine effectiveness for all-cause deaths range from 27%-50%.

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McLean, Va.: I am really disgusted with the flu vaccine shortage for the second year in a row. Fortunately, I was able to get a vaccine last Friday on my third trip to a Safeway clinic, after standing in line for two hours. Last year I was not able to get a vaccine at all. Getting a vaccine used to be easy. I understand that the current problems still trace back to Chiron. How can this be so messed up? What would it take to make safe and available flu vaccines a priority?

William L. Atkinson: I'm glad you got your vaccine. It is important to remember that it is still very early in influenza season. It is not necessary to rush out and get a dose today. There is more vaccine in the pipeline, and there should be plenty for everyone by the end of November. Even December is early in the influenza season.

Making safe and effective influenza vaccine available IS a priority of CDC, FDA, and the manufacturers. Manufacturing vaccine is very complicated, and unanticipated glitches will happen. Everyone needs to just be patient, and keep in mind that getting your vaccine in November or December is fine and will still help keep you health this winter.

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re over-65 vaccination: With respect to annual flu, I completely agree that this should be a priority. But pandemic flu is a completely different situation and I worry that this kind of extrapolation, from what we do normally to what we should do during a pandemic is what will get us in trouble. Shouldn't infrastructure workers (outside of pharma...e.g., people who maintain our eletric grid, telephones, etc.) be prioritized?

William L. Atkinson: We agree that healthcare and public safety/instructure personnel should be a priority in the event of a pandemic (if you exclude "pharma" who is going to make the vaccine?)

This is one of the most difficult decisions that will need to be made in the event of another pandemic - whether to vaccinate those most likely to die or those needed to care for the sick and keep the lights on. There is no easy solution for this.

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Milwaukee, Wis.: From a public health and epidemiological standpoint, how do we compare the public policy implications between flu awareness and the 40,000 deaths that occur each year on our Nation's roads? To what extent is the salience of our fear of disease and the unknown influencing our fiscal priorities? I am certain there are no easy answers, but would appreciate your input to this concept.

William L. Atkinson: You are correct that there are no easy answers to this. I leave these issues to the policy makers to contemplate.

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Lancaster, Pa.: I don't really understand what goes into epidemeology. How do people in your field figure out hospitalization and death estimates? Do you have a lot of people in the field doing data collection? Some information on how these estimates are derived and what goes into being an epidemiologist would be helpful. Thank you for your important work!

William W. Thompson, Ph.D.: Influenza associated hospitalizations and deaths are estimated using national mortality and hospitalization data. We fit models that correlate the circulation of influenza viruses with changes in hospitalization and death rates. Currently, influenza viruses are associated with 36,000 deaths and more than 200,000 hospitalizations annually in the United States.

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Madison, Wis.: Dr. Thompson, As a graduate of the University of Wisconsin, I am sure you've experienced winter weather. My question is why is it that we get sick with flu and other diseases in the wintertime and not so much in the summertime? We are in crowds in both seasons aren't we? Also, are the flu seasons different for people in the southern hemisphere such as those in Australia?

William L. Atkinson: I'm from Kansas City and it get's pretty cold in the winter there as well.

I'm not sure anyone really understands the seasonality of influenza. In the tropics it occurs throughout the year. It is likely due in part to the fact that we are more likely to breathe recirculated air in closed spaces when it is cold outside. In temperate climates influenza season occurs (usually, but not always) when it is cool and dry. The temperate areas of the southern hemisphere (Australia, New Zealand, etc) have their cool dry (winter) season in our summer, and that is when their influenza season peaks. We watch closely what happens during the southern hemisphere winter because we often experience the same type of influenza season 6 months later.

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Anonymous: An alternative to the injectable flu vaccine is FluMist, the nasal spray. But it is restricted to people in the 6- to 49-year-old age bracket. I can understand why a live-virus vaccine might not be suitable for young children, but why shouldn't someone who is 50 or 55 or 60 have access to it, especially someone with no particular health problems?

William L. Atkinson: The Food and Drug Administration has not approved FluMist for use in people older than 49 years because the company that produces it has not provided data on the safety and effectiveness of the vaccine in older age groups. It is possible that FluMist will be approved for children as young as 2 years in the next year or so.

Doing studies of "alternative" influenza vaccines is difficult in people 50 and older, because we already recommend INACTIVATED vaccine routinely for this group. To test a new vaccine in a group included in a routine vaccination recommendation means witholding the recommended vaccine. This poses ethical issues for the trial. It is possible that in the future the age range could be raised by utilizing surrogate efficacy markers such as antibody titers after vaccination.

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William L. Atkinson: Thank you for your questions. Please visit the CDC influenza Web site for more information on influenza activity, vaccine availability, tips on staying healthy and much more.

Remember: be patient, your vaccine is coming. And wash your hands.

William Atkinson, MD

National Immunization Program, CDC

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