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Next question in swine flu - who gets vaccinated?

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  • Next question in swine flu - who gets vaccinated?

    This article brings up an important point....given the atypical nature of novel A/H1N1, should vaccine guidelines be changed, as if so - to what?
    --------------------------------------------------------------------------------------

    Fri Jun 19, 2009 2:55pm EDT

    By Maggie Fox, Health and Science Editor - Analysis

    WASHINGTON (Reuters) - Drug makers are gearing up to make vaccines against the new H1N1 virus, starting test batches and pledging free doses for poor countries.

    Governments are pledging billions for the vaccine -- the United States has set aside $1 billion, the Netherlands ordered 34 million doses and Australia has ordered 10 million doses as the World Health Organization declared a pandemic.

    Yet no one is sure yet whether even to give the vaccine to anyone and if so, who should get it.

    Usually the guidelines for influenza vaccination are clear -- give it to the oldest, the youngest and the sickest. In an average year, influenza is a factor in 250,000 to 500,000 deaths, and in developed countries, 90 percent are the elderly.

    But the new H1N1 swine flu virus is not behaving typically. It has dragged the Northern Hemisphere's flu season well into June, although influenza usually dies way down by April.

    "The fact that we are seeing ongoing transmission now indicates that we are seeing something different," Dr. Daniel Jernigan of the U.S. Centers for Disease Control and Prevention told reporters this week.

    Most cases are in people aged 5 to 24 -- usually the last group to get seriously ill from flu and the last group vaccinated during a normal flu season.

    There have been few serious H1N1 cases among the elderly, perhaps because they have some pre-existing immunity to a similar H1N1 that circulated in the past, or maybe because their immune system response is different -- flu experts do not know yet.

    To decide what to do, WHO officials will have to watch and see what this new strain does.

    REAL-TIME EXPERIMENT

    As WHO Director-General Dr. Margaret Chan said at the beginning of the pandemic last month, the world is watching it unfold in real time -- and much of humanity is taking part in a real-time experiment.

    If the virus continues to affect mostly older children and young adults, the strategy should be clear -- vaccinate those groups. And at least one study supports this idea for other reasons.

    This week a team at Britain's University of Warwick said computer models suggest that vaccinating children aged 6 months to 18 years may be the best way of using limited supplies to control the pandemic.

    Because schools can be epicenters for spreading flu infection, including the new H1N1, this might make more sense than trying more general approaches. Vaccinating schoolchildren would prevent them from spreading it to two more vulnerable groups -- the elderly and the very young.

    It may also protect those clearly more at risk from both H1N1 and seasonal flu -- people with asthma, diabetes and heart disease, suppressed immune systems and pregnant women.

    By Friday, WHO had confirmed 44,287 cases of the new flu and 180 deaths, with Laos, Oman, Papua New Guinea, South Africa all reporting their first cases.

    The United States alone has more than 21,000 cases with officials saying there are likely at least 10 times that many, and 87 deaths.

    WHO estimates vaccine makers could produce up to 4.9 billion pandemic flu shots a year at most. That would depend on how many doses people needed and whether vaccine boosters called adjuvants could be used to stretch out the doses.

    Even this best-case scenario would leave more than a billion people unvaccinated.

    Vaccine maker Sanofi-Aventis, which says it makes 40 percent of the world's supply of flu vaccine, says at full capacity its two Pennsylvania factories can make 150 million doses of seasonal influenza vaccine a year. Its French plant can make 120 million doses per year.

    This would triple for H1N1, as the seasonal vaccine is a cocktail of three different viruses.

    Other companies that make flu vaccine include Novartis AG, Baxter International Inc, GlaxoSmithKline and Solvay.

    http://www.reuters.com/article/GCA-S...55I4ZM20090619
    "The next major advancement in the health of American people will be determined by what the individual is willing to do for himself"-- John Knowles, Former President of the Rockefeller Foundation

  • #2
    Re: Next question in swine flu - who gets vaccinated?

    Vaccinating Children Could Be Effective At Helping Control Spread Of Influenza
    From RedOrbit Posted on: Wednesday, 17 June 2009, 12:10 CDT
    Targeting children may be an effective use of limited supplies of flu vaccine, according to research funded by the Wellcome Trust and the EU. The study suggests that, used to support other control measures, this could help control the spread of pandemics such as the current swine flu.

    SNIP

    Pharmaceutical companies have also stepped up production of vaccines effective against this particular strain of the virus. However, if the spread of the disease increases significantly in the autumn, as some scientists predict, it is unlikely that supplies of the new vaccine will be sufficient to vaccinate entire populations.

    In research published in the journal Epidemiology and Infection, Dr Thomas House and Professor Matt Keeling from the University of Warwick have used computer modelling to predict the spread of pandemic influenza and to look at ways of controlling it effectively, particularly where supplies of vaccine are not sufficient for universal coverage.
    The researchers showed that, as might be expected, the disease is likely to spread fastest in densely-populated conurbations, suggesting that these should be priority areas for tackling the spread. However, they showed that vaccinating entire households at random was an inefficient use of resources; instead, vaccinating key individuals offered sufficient protection to others in their household.

    Although a simplification of the complex reality of pandemic flu transmission, the researchers believe their model provides a robust argument for vaccinating children.
    "Our models suggest that the larger the household - which in most cases means the more children living at home - the more likely the infection is to spread," says Professor Keeling. "This doesn't mean that everyone in the household needs to be vaccinated, but suggests that vaccination programmes for children might help control a potential pandemic."
    The researchers argue that targeting children for vaccination would not only help protect those at greatest risk of exposure to the virus, but would also offer protection to unvaccinated adults. This so-called "herd immunity" effect would mean that significantly less vaccine would be necessary to help control the spread of the virus than if it were offered to everyone.

    "Given that children are generally at particular risk from the disease, we believe that vaccination programmes for the young can be justified," says Dr House. "Although not sufficient to prevent a pandemic in themselves, such steps may support other control measures such as social distancing, antiviral drugs or quarantine."
    The current study focuses on household transmissions. In the event of a disease outbreak, other modes of transmission are also likely, such as at work or on public transport. However, data for these modes is harder to come by. Professor Keeling and Dr House, together with colleagues at the University of Liverpool, are currently running www.contactsurvey.org, a survey on contact patterns which they hope will help to quantify the relative importance of each context.
    SNIP

    Link: http://www.redorbit.com/news/h...
    The Doctor

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    • #3
      Re: Next question in swine flu - who gets vaccinated?

      Vaccinating Children Could Be Effective At Helping Control Spread Of Influenza

      This is a very interesting proposal and one that I think has great merit. Our dear children are those that most commonly bring infectious diseases home to the family and their friends. This is a fact that any parent can attest to in spades. Once children begin associating with their peers, they acquire an amazing number of bacteria and viruses that are readily transmitted to the rest of the family, especially to parents. In my experience as both a parent and a physician it appears that most of this transmission occurs during the first 6 years of life but this observation is purely anecdotal and should not be relied upon as fact.

      Vaccinating the youngest members of our population first makes tremendous sense. Focusing the limited quantities efficacious pandemic vaccine on this relatively small portion of the human population as a whole has the potential to blunt the transmission rate of the pandemic virus more efficiently than any other proposal considered to date.

      This strategy will be effective in both the developed and less developed world meaning that it has the potential to be universally efficacious.
      The Doctor

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      • #4
        Re: Next question in swine flu - who gets vaccinated?

        Vaccinating children first is an equitable use of the limited supply of a scare resource that a well-matched vaccine will be this fall.

        By equitable, I mean it needs to be offered to ALL CHILDREN and in EVERY PART OF THE WORLD, not just in the rich countries.

        Some parents may not want their kids vaccinated, that will be their choice but all children everywhere should be given the opportunity to receive it.
        Equitable then means without regard to race, ethnicity, economic status or what country the child lives in.

        What is a child? Not an unimportant question but I think that the definition for the purpose of who to vaccinate first probably should be based upon the time of thymic involution. Why? Because it appears that the thymus gland is what conveys immune tolerance to children. Once this gland involutes or dies away, the child's immune system is pretty much constituted and assumes the adult state. In most children, this occurs around the time of puberty.

        Puberty differs by gender and race. For instance girls enter puberty before boys irrespective of race but those of African decent typically enter puberty at the youngest age, followed by Caucasians and then Asians. The age of puberty onset is broad for humans ranging from 9 years old to 16 years of age.

        So, if we just picked an age of say 15 in order to be as inclusive as possible as our cutoff point for who is and who is not a child for the purposes of vaccination and also eliminated those aged less than 6 months of age from inclusion since their immune system is not able to respond protectively to vaccination, then we would have defined an optimal age group for priority vaccination.

        Extrapolating from the data found in the CIA Fact Book for 2006, I estimate that about 14% of the world’s population would be considered “children” using the above definition. Since the human population of the earth is about 6.7 billion today that equals 938 million kids. Not very many when you think about it and well within the influenza production capacity of the world even if the antiquated chicken egg method was used.

        However, today, both Novartis and GSK have approval for producing influenza vaccine using transformed mammalian cell cultures which takes only about 13 weeks to produce, half the time of the chicken egg method and better yet the cell culture method can be scaled up infinitely. So, making enough vaccine for these children is well within the reach of current producers whom will still have plenty left over to sell to the rich in the developed nations for a fat profit.

        What’s more we probably don't need to vaccinate all billion some odd of this whole group, probably half would be enough to convey herd immunity. What's more, the very best way to vaccinate them would be by using an attenuated live virus given by nasal spray like Medimune's Flu Mist. Why? Because the kids that contract a very mild flu from this vaccine will spread it around to their family members who would get it to some extent and thereby be secondarily vaccinated and protected.

        Grattan Woodson, MD
        The Doctor

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