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Swine Flu, H1N1: Frequently Asked Questions--With Expert Answers

family-fluSwine flu FAQs—with answers straight from the experts!



pandemic-spreading-germsPANDEMIC QUESTIONS AND ANSWERS
Answers by William Schaffner, M.D., professor and chair of the Department of Preventive Medicine at Vanderbilt School of Medicine.

Q: Can you remember a time when the world prepared for a health threat to this extent?

A: A few other global events come to mind, but nothing like this.

SARS coming to the Western Hemisphere out of China and Hong Kong was much more localized geographically, as have been past cholera pandemics—none of which affected the United States.  Some would mention AIDS.  That deadly infection certainly has swept around the world, albeit at a slower pace.  Influenza is the infection that can—and periodically does—involve the entire globe.  In this regard, recall the international anxiety about bird influenza a few years ago.  Fortunately, the bird-flu virus still has not developed the genetic capacity for facile transmission among humans.  For those with long memories, there were the influenza pandemics of 1957 and 1968.  So, nothing quite like this for a long, long time.

Q: What does "pandemic" mean, anyway? Does it mean millions will die?

A: A pandemic is a global epidemic caused by a new virus that rapidly spreads to many countries around the world.  The concept that such an infection usually causes severe disease is implicit, but as the current pandemic of H1N1 infections demonstrates, all new influenza viruses do not necessarily produce widespread lethal disease. That is why some (myself included) have quibbled about the use of "pandemic" in this instance.

Q: Is H1N1 already a pandemic?

A: Because H1N1 is a new virus that has affected a very large number of countries in widely separated parts of the globe, it fulfills the [World Health Organization] definition of a pandemic.  Because severity was not part of their definition of pandemic, WHO intends to review the definition for future use.

Answers by Stephen G. Jones, M.D., board-certified geriatric-medicine specialist and associate professor of clinical medicine at the Yale School of Medicine. Dr. Jones is also a member of the Yale committee that looks into preparation and response to pandemic flu in conjunction with the Office of Emergency Preparedness.

Q: Can people with egg allergies get the H1N1 vaccine?

A: The flu vaccine is presently made by growing the virus for the vaccine in eggs.  If people have received the flu vaccine in the past without an allergic reaction, they should be just fine receiving this year's vaccine.  However, if they have had a reaction in the past, or have a known egg allergy, they should consult their physician and consider getting tested to see if they actually do have an egg allergy.  It is important to know that you cannot get the flu from the flu vaccine.

Q: Can you receive the H1N1 and seasonal flu vaccines together?

A: The CDC has yet to announce their recommendations in this regard. However, the seasonal flu vaccine will be available to all at least a month earlier than the H1N1 Vaccine. People should receive their seasonal flu vaccine as early as possible and not wait for the H1N1 vaccine, which will avoid having to receive them together.

Q: I heard that they're having trouble making enough vaccine. True?

A: The issue isn't as much about if there will be enough vaccine as it is about when it will be available. The process of making the vaccine requires several weeks of growing the virus in eggs, and preparing and testing it for safety before distribution can even begin. Production has been ramped up in an attempt to meet the need. We may have to wait at least until November to have enough for everyone.

Answers from Marci Drees, M.D., M.S., FACP, DTMH, epidemiologist with Christiana Care Health System in Wilmington, Del.

Q: Since we don't know how many H1N1 cases are out there, can we even guess at whether the percentage of deaths is higher or lower than with regular flu?

A: During a typical flu season, we do not count every single case of flu that occurs.  The CDC has a number of different systems in place to monitor influenza trends, but none of them are designed to capture all possible cases.  What we do know is that during an average flu season, approximately 200,000 people are hospitalized and 36,000 people die in the U.S.  As of 8/20/09, fewer than 8,000 people in the U.S. have been hospitalized and around 500 have died from novel H1N1 flu, despite widespread transmission of the virus in the community.

So while we can't calculate an exact percentage of the total number of flu cases that cause severe disease, public health authorities are comfortable stating that up to this point, H1N1 has not been a severe illness for most of those who have gotten it.

Q: What can you discern from the numbers as case counts rise? Anything (since they've stopped testing all the flu to see if it's H1N1)?

A: Again, although not every cases is being counted, state and local health departments and the CDC are tracking influenza by looking at hospitalizations for H1N1, certain populations (such as pregnant women), the percentage of outpatient visits for a flu-like illness and other means.  All of these indicate that over the past one to two months, the rate of new infections has decreased significantly.  Of those ill people who are being tested for flu, the circulating strain is nearly entirely H1N1 (i.e., none of the usual seasonal flu strains are still circulating).


Last updated and/or approved: September 2009.

Comments (2)add comment
Can you get the swine flu again? Answer
written by Leigh Ann , October 22, 2009

Hi, H Bjerke. Thank you for asking whether you can get the swine flu more than once and whether you should get the vaccine if you've had H1N1. These are questions many are wondering about.

The CDC answers your first question on their Web site with a long "We don't know":

"Please remember that the H1N1 virus is new and research is being conducted to better understand its characteristics. In addition, although data on H1N1 are scarce and this illness is still being studied, it is also important to know that flu viruses undergo frequent changes during an outbreak."

"In general, exposure to a particular strain of flu virus will protect you against that strain in the future. However, it will not protect you from infection by other flu virus strains.

"Please also note that it is possible for a person to be infected with the seasonal influenza (flu) virus more than one time in a season, because several strains of flu virus circulate each year."

Per your question about whether to get the swine flu shot after you've already had H1N1, the CDC warns that you can only be sure you had H1N1 if it was confirmed by a test called real-time reverse transcription-polymerase chain reaction (RT-PCR). Yet, they say, "Most people ill with a flu-like illness since this spring have not been tested with RT-PCR." Even if you got sick after being exposed to someone with H1N1, don't assume you had the same thing, they urge.

But let's say an RT-PCR test did confirm that you had H1N1. The CDC still says you might want to get vaccinated. Unless you're severely immune compromised, you'll "likely have some immunity to subsequent infection with 2009 H1N1 virus. But, vaccination of a person with some existing immunity to the 2009 H1N1 virus will not be harmful."

Basically, I don't think anyone has a definitive answer in what's turning out to be a confusing flu season.

Here's the CDC's flu questions page:

Wishing you the best of health,

Leigh Ann Otte
Managing Editor

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H1N1 Vacccination
written by H Bjerke , October 16, 2009

If you have already had the "swine" flu can you get it again? If you have had the virus should or do you need to be vaccinated?
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