"The situation continues to evolve rapidly. As of 06:00 GMT, 1 May 2009, 11 countries have officially reported 331 cases of influenza A(H1N1) infection," states the current news release from the World Health Organization.
Inzune Hwang, lead in the Technical Security Unit of the Centers for Disease Control and Prevention, was online Friday, May 1, at 12:30 p.m. ET to discuss the latest information on the swine flu, including advice on travel, symptoms, when to seek medical attention and food consumption.
Washington, D.C.: I had a meeting this morning with a colleague from Mexico who came to D.C. on Monday. My colleague is not sick, but I was wondering how long the incubation period is and how much I should worry about the potential for infection. Is it possible for her to carry the flu if she is not exhibiting symptoms?
I have a 9-month baby at home and am most worried about her.
Inzune Hwang: Our current calculations on the incubation period, based on the case information that we have, is 1-5 days. It is possible to be infected and shedding virus without symptoms. Therefore, it is appropriate to use good hygiene precautions, such as handwashing, use of hand sanitizers, and covering your mouth when you cough or sneeze
Inzune Hwang: Good afternoon, everyone. This is Inzune Hwang, MD, MPH. I am the Preparedness Medical Officer for CDC's Influenza Division.
Washington, D.C.: We hear that officials from the World Health Organization today cautioned the public against jumping to any conclusions about the virulence -- the lethality -- of the swineflu virus. Can you explain this warning?
Inzune Hwang: The first country to be affected by this new influenza virus appears to be Mexico. They have reported a number of hospitalizations and deaths. Laboratory testing has confirmed that some of the patients who died had influenza H1N1 (2009)(swine-lineage). Although we have not yet detect many cases of severe illness and death in the United States and in other countries, it is too early to draw any conclusions
Atlanta, Ga.: Good afternoon -- we read a lot about new cases of H1N1 popping up -- 50 today, 100 tomorrow... but of the number that have contracted the virus, how many have perished? What's the percentage? If we've had 100 diagnosed in the U.S. since Sunday, and only 1 has died, doesn't that mean there's a 99 percent survival rate? We never get numbers like that... can you enlighten? Our media seems to be stirring a panic pot
Inzune Hwang: Great question. Of the 141 cases that we have confirmed diagnosis of Influenza H1N1 (2009)(Swine-lineage)to date, we have only 1 reported death. Although that is slightly less than 1%, we must consider that the entire population is currently susceptible to this virus.
In the 1918 pandemic, it was estimated that the case fatality ratio was 2%. That does not mean that this current outbreak will be half has severe. It means that we must continue to gather the best information that we can to determine the case fatality ration as accurately as possible.
Montgomery Co.: I am a high school teacher in a school that serves a large immigrant population, and I am 7 months pregnant. I sense that I'm at greater risk, but I'm not sure what actions to take to keep myself and my baby safe without completely over-reacting (other than washing hands, limiting close contact, etc.). Should I be considering taking time off and staying home during this time?
Also, my sister-in-law is traveling to Mexico next week and will be returning just in time to incubate some germs and then throw me a baby shower. Part of me wants to cancel, but is that over-reacting?
Inzune Hwang: Pregnant women are at higher risk for serious illness and complications than other persons. So, it is important to take appropriate precautions. CDC has posted guidance on www.cdc.gov regarding use of personal protective equipment, and, if circumstances warrant, use of antiviral medications.
Your decision to take time off is an important and personal one. You have to consider the financial implications, as well as the fact that it will be some time before an immunization is available for this strain. We should have better understanding of the risks of this virus as time goes on.
The risk of exposure to your sister-in-law is also a tricky one. We know Mexico is more severely affected, and have issued a travel warning against unnecessary travel there. We also know that there is a 1-5 day incubation period before someone infected may show any symptoms. You may consider postponing the shower 10-14 days after she returns if you are concerned. The goal of your shower is to pour happiness and love on you and your baby, not give you more concern.
Washington, D.C.: Should I cancel plans this weekend to see friends (with babies) if I have recently been in contact with people from Mexico?
Inzune Hwang: Our current, albeit, limited data on the incubation period for this new influenza virus is 1-5 days. General recommendations about how long to watch out for symptoms is at least 2 incubation periods. Therefore, if you are concerned, a general suggestion would be to consider avoiding non-essential social contact for 10-14 days.
Richmond, Va.: Are there any statistics on the number of people who got or didn't get the flu shot this year, and would it make a difference on the severtity?
Inzune Hwang: Over 130 million doses of seasonal influenza vaccine were produced for the 2008-2009 flu season. I believe approximately 25 million were not shipped. We cannot currently measure exactly how many doses were actually given to individuals.
We are currently in the process of determining how much cross protection seasonal influenza vaccine provides from this new H1N1 virus. Our preliminary data suggests little to no significant cross protection.
Vienna, Va.: If about 30,000 people die yearly from regular flu, then isn't this swine flu thing not a problem? Or contri-wise, why don't we have location maps and panic every winter with regular flu? I'm at a loss to understand the fuss.
Inzune Hwang: At CDC our goal is to minimize the spread and severity of any influenza. So, we work hard to prevent even one death from influenza. Our challenge in the present circumstance is to determine how this new influenza H1N1 strain behaves compared to other human influenza strains that circulate. The worst pandemic that we have on record, in 1918, killed many more than 30,000 and we want to be sure that does not occur again.
Actually, we do have maps on seasonal flu activity in every state, updated weekly on www.cdc.gov/flu. Look for FluView.
Redmond, Wash.: Good morning. Is it possible for this flu virus, in it's present form, to go from humans back to birds, or swine, and thus have more than one reservoir at a time, or must it mutate to again infect animals?
Inzune Hwang: Excellent questions. The short answer is yes! This current virus is a reassortant, meaning it has swine, avian, and human genes in it. It evolves that way because some animal was infected with multiple strains at once and produced a virus with a combination of genes (reassortment). At some point, the slow mutation of genes combined with this reassortment process produces a virus that can transmit easily in humans (our current situation). It is possible that it can transmit back to its source animal reservoir, or perhaps to another.
We have CDC veterinarians working with those from FAO and OIE (the animal equivalents of WHO) investigating the animal situation in Mexico to try to find an animal source.
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