H1N1 Influenza Center

From the Publishers of the New England Journal of Medicine

The Sudden Birth of H1N1 “Swine” Flu: What Does the Future Hold? The Sudden Birth of H1N1 “Swine” Flu: What Does the Future Hold? The Sudden Birth of H1N1 “Swine” Flu: What Does the Future Hold?

The past and future flu virus …

In recent weeks, an international outbreak of illness has occurred; it is caused by a new strain of influenza virus (2009 A/H1N1) that contains a combination of swine, avian, and human influenza virus genes. In this post, Anthony L. Komaroff, MD, provides some additional background information.

Pigs, birds, and humans are each susceptible to many flu viruses. Typically, these viruses infect only one species. However, sometimes these viruses swap genes and create new viruses that can infect more than one species. Even then, new viruses that are capable of infecting two species typically are very difficult to transmit from human to human. Sometimes, however, further recombinations or mutations of genes create a virus that can spread rapidly among humans – thus creating a global pandemic. The worst global pandemic in modern times was the flu pandemic of 1918-1919. It affected about a third of the human race and killed at least 40 million people in roughly 1 year – more than have been killed by AIDS in 3 decades.

The World Health Organization and the CDC have confirmed that the new swine flu virus is transmitted between humans. Almost surely, like other flu viruses, it can be transmitted by aerosol and by skin-to-skin contact with an infected person. The new virus is resistant to amantadine and rimantadine but is sensitive to oseltamivir (Tamiflu) and zanamivir (Relenza). Based on experience with other flu viruses, treatment would be most effective if given within 2 days of symptom onset. Obviously, no vaccine is available yet for the new virus, and the CDC has expressed doubt that the current flu vaccine offers much, if any, protection. People should be considered to be contagious until at least 7 days after symptom onset; with children, that time might be as long as 10 to 14 days.

Influenza viruses are transmitted more easily in cold dry air. Even if the current outbreaks in the northern hemisphere quiet down in the next weeks and months, some experts are concerned that the virus will produce epidemics in the southern hemisphere during winter (June through August), and then return with a vengeance to the northern hemisphere in its fall and winter seasons. That’s exactly what happened in the pandemic of 1918-1919. However, that pattern doesn’t always happen: The swine flu outbreak that occurred at Fort Dix, New Jersey, in early 1976 did not return the next winter. However, in anticipation that it would, 40 million people were immunized, and about 1 in 100,000 vaccinated people developed Guillain-Barré syndrome.

If a vaccine against the current H1N1 virus is ready in the fall, government officials will face several difficult decisions, without much data to predict the future. First, they will have to decide whether to recommend widespread immunization against 2009 A/H1N1, even if no evidence of its resurgence is available – and without knowing whether a vaccine against this new swine virus would also provoke rare cases of Guillain-Barré syndrome. Second, policy makers will have to decide whether to recommend immunization against other circulating strains of human influenza virus, as well.

Anthony L. Komaroff, MD


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8 Responses »

  1. There are millions of people living in the developing world with not much hope of either antiviral therapy or immunisation available for them in the near future. WHO has supplies to treat a tiny handful of people in a given developing country as a glimmer of hope. We, in the developed world should not forget these people while stockpiling antivirals for the near future.

  2. I’m afraid of excessive panic about this still unknown issue (H1N1 pandemic). Anyway, mortality rates seems not to be high so far. Why isn’t there the same worry and midia evidence about hungry, pneumonia and diaorrhea in poor countries?

  3. I’m from Mexico City and live near the US Border. I agree with Andrea that it is not so dangerous this H1N1 virus, even though there have been about 55 death in Mexico, which represents less than 3% of the cases reported.

    Now Mexicans, we are being treated poorly by other countries. Singapoor, China, Cuba, Argentina closed their airports to Mexican Flights. This is not the solution.

    We, as a doctors needs too educate the population with the prevention skills, and to consultate and not self-medicated. Thats why pandemic got out control.

    I hope that end as soon as posible.

  4. I can`t believe that someone may say this issue about the pandemic of swine flu may be not so important cause i think is very important .If people in poor countries are having problems to survive in their daily lives imagine them with this H1N1 virus -the desease will spread around the world more rapidly due to their poor means and few medecines.This virus can become more letal(mutations) and i wouldn´t like to be among the one third of the world population that could figures on mortality numbers even if for the moment this could be just a possibility ,but among the health care people this is a very dangerous possibility and the reason why our cientists are trying to find a vaccine.There are problems in the world that belongs to all of us and to the politicians eleged by us (in democratic countries)that hesist since the beginings of times and that never changed till nowadays ,wich is sad , but this has nothing to do with such important issue as H1N1 virus in this moment. We should worry .The worries of some may be the salvation of many and this many might be a mother ,a father,a son or a relative of us …we should think about it… Health student,Corroios,Portugal

  5. OK, every day, my alarm clock-radio informs me on the morning news of the new “cases” of H1N1. Some countries do thermoscreeing at airports, others give out Tamiflu. Others muddle the issue by closing off large areas of inter-human contact. But which is the real issue: the sick or the spread of the virus? If the former then it is like Ebola, whoever gets it gets it and there’s nothing we can do as the story just ends for those cases. But Ebola we know if fatal in about all cases. H1N1 is not presented to us as viral contact by a person’s immune system with it, but rather symptomatically– felt sick, stayed home or went to the ER (God help those overwhelmed ER guys whose real skill is in putting a finger on a bleeder or pounding a chest to start the heart). A honcho ID old guy at John Hopkins tells us to go for fever, the pathognemonic sign on H1N1 (???????)
    Since when is fever a sign of virus manufacture and shedding? Without spread rate and pattern of BOTH clinical and sub-clinical, how well can we say we are dealing with the disease? Let’s say 10 people act sick, three have fever and one died: so what? What if the virus were passed among these ten people from repeated intimate contact; what if they all open and close the same door knob; what if they all eat at the same restaurant……All this is the minutia of contagion. But what if these people never met and 2,000,000 over a state the size of Texas show serologic sign of contact with the virus and all cluster in 20 different areas– NOW THE PICTURE IS DIFFERENT, isn’t it….not to speak of how many become virus factories?

    Please don’t let me know about “confirmed” cases singled out by the index of suspicion flag waved by the old ID guy…..What about the thousands who came in contact, mounted a serologic defense and soon lost infectivity. Can anyone pllleeeeaaassssee address those studies. For the serologic pattern will tell us how easily transmittable is the virus and how virulent it is; also how stable it might prove to be in terms of mutation (is it as scary as HIV when we found out it mutates two base pairs per generation?). I remind you that we were able to clinically get an epidemiological handle on HIV working only with serological screening. Please, please, please don’t tell me that there exists no easy qualitative screening test for H1N1. Please lead me to the studies if they exist. I’m too busy dealing with diabetes, atherosclerosis, inflammation and Cheney’s psychopathologic attempt to define Muslims as another contagious virus, so I had little chance to do the library searches. Thank you from a 9/11 survivor who is, therefore, not as scared by H1N1 as I am by D. Cheneyticus Ebola-like infection invading my TV.

  6. Julian Sanchez

    The H1N1 virus is a infectious disease that have a great attack rate but your lethal isn´t so high, for this there problems in the control of this disease and is very important your control, also the absence of a diagnostic method with sensibility and especificity high, and likelihood ratios acceptable make complicated your treatment.

    Julian Sanchez Castillo, MD
    Bogota, Colombia

  7. The H1N1 virus is a infectious disease that have a great attack rate but your lethal isn´t so high, for this there problems in the control of this disease and is very important your control, also the absence of a diagnostic method with sensibility and especificity high, and likelihood ratios acceptable make complicatedbelieve that someone may say this issue about the pandemic of swine flu may be not so important cause i think is very important .If people in poor countries are having problems to survive in their daily lives imagine them with this H1N1 virus -the desease will spread around the world more rapidly due to their poor means and few medecines.This virus can become more letal(mutations) and i wouldn´t like to be among the one third of the world population that could figures on mortality numbers even if for the moment this could be just a possibility ,but among the health care people this is a very dangerous possibility and the reason why our cientists are trying to find a vaccine.There are problems in the world that belongs to all of us and to the politicians eleged by us (in democratic countries)that hesist since the beginings of times and that never changed till nowadays ,wich is sad , but this has nothing to do with such important issue as H1N1 virus in this moment. We should worry .The worries of some may be the salvation of many and this many might be a mother ,a father,a son or a relative of us …we should think about it… Health student,Corroios,Portugal your treatment.

  8. I think I am a little worried about this flu shot and nasle becase people say they feel weird after words. Dose any one out there feel the same speak up!?