Avian flu != Regular Flu?
October 22, 2005 11:09 PM Subscribe
Is regular flu vaccine effective against the avian flu?
The 'avian' flu virus is a separate, distinct pathogen from the viruses we're inoculated against each fall. Actually, the flu vaccine is different from year to year - its composition is based on a prediction made by CDC. Sometimes they get the prediction wrong, as they did a couple of years ago, and vaccinated folks get the flu anyway. But I digress.
The great worry with this avian flu is that it will make the jump from making birds sick to making people sick. It has not done so as of yet. If it does, we won't have a way to treat it except by treating the symptoms - and the symptoms will be severe enough to cause respiratory failure and death in many, many people.
posted by lambchop1 at 11:54 PM on October 22, 2005
The great worry with this avian flu is that it will make the jump from making birds sick to making people sick. It has not done so as of yet. If it does, we won't have a way to treat it except by treating the symptoms - and the symptoms will be severe enough to cause respiratory failure and death in many, many people.
posted by lambchop1 at 11:54 PM on October 22, 2005
Best answer: Responses so far are correct. The flu vaccines they make each fall are actually not just a single vaccine. Each dose contains several vaccines, against possible strains of the influenza virus that are going around. The virii mutates often (each year they are totally different) and the vaccine can only target a limited number of strains. There is no general purpose "flu vaccine". The avian virus is a specific strain called H5N1, but if and when it starts moving from person to person, no vaccine we have today will stop it.
Researchers are studying an older virus that killed millions of people in 1918 called H1N1, in the hopes of coming up with a vaccine against H5N1. Currently, all we have is a drug from a company called Tamiflu which fights the symptoms once you're already infected, possibly increasing your chances of survival. Governments around the world are placing orders to stock up on the drug (the US has ordered 65 million doses, I believe) in preparation for the potential pandemic.
posted by knave at 12:17 AM on October 23, 2005
Researchers are studying an older virus that killed millions of people in 1918 called H1N1, in the hopes of coming up with a vaccine against H5N1. Currently, all we have is a drug from a company called Tamiflu which fights the symptoms once you're already infected, possibly increasing your chances of survival. Governments around the world are placing orders to stock up on the drug (the US has ordered 65 million doses, I believe) in preparation for the potential pandemic.
posted by knave at 12:17 AM on October 23, 2005
And I believe that human-to-human transmission has not yet occurred -- a good thing, but certainly not improbable in the future.
posted by davidmsc at 12:59 AM on October 23, 2005
posted by davidmsc at 12:59 AM on October 23, 2005
Because the vaccine needs to closely match the pandemic virus, large-scale commercial production will not start until the new virus has emerged and a pandemic has been declared. Current global production capacity falls far short of the demand expected during a pandemic. (WHO)
Flu shots are still important, because they lessen the chance that normal flu combines with avian flu, resulting in a more dangerous flu (combining the lethality part of avian flu with the easily spreading part of normal flu)
posted by davar at 3:45 AM on October 23, 2005
Flu shots are still important, because they lessen the chance that normal flu combines with avian flu, resulting in a more dangerous flu (combining the lethality part of avian flu with the easily spreading part of normal flu)
posted by davar at 3:45 AM on October 23, 2005
I believe that Tamiflu and other anti Influenza medications (there are several) is actually effective at preventing influenza (read: avian flu, H5N1, etc)
It costs quite a bit though, so i'm not sure how feasible it is as a long term preventative. I don't think the anual anti-flu injections are particularly effective against avian flu currently either as they are usually vaccines iirc. I could be totally wrong on that bit though.
posted by alexst at 5:43 AM on October 23, 2005
It costs quite a bit though, so i'm not sure how feasible it is as a long term preventative. I don't think the anual anti-flu injections are particularly effective against avian flu currently either as they are usually vaccines iirc. I could be totally wrong on that bit though.
posted by alexst at 5:43 AM on October 23, 2005
Tamiflu is effective against HN51 and friends. The problem is that Roche can just barely keep up a supply for a regular flu season, and has only just begun negotiations with other companies to produce the drug.
posted by jimfl at 8:49 AM on October 23, 2005
posted by jimfl at 8:49 AM on October 23, 2005
There is a vaccine for H5N1 that has been tested on small mammals, and is undergoing some limited human trials. The US centres enrolling human volunteers for the experimental vaccine are in LA, Baltimore, and Rochester, New York.
Some countries are advocating widespread vaccination with some variation of this strain as a prophylactic.
There are, however, several problems with this. The first is that if and when H5N1 mutates into a pandemic strain (either by hybridisation or through internal modification), it is unknown how much if any protection the existing H5N1 vaccines will offer. The virus's protein coat will undoubtedly be significantly modified and it may be divergent enough that antibodies created using the original H5N1 template will fail to recognise the new pathogen.
There are those that say, to hell with this, let's just vaccinate anyway and hope that some or many people get at least some moderate protection, even if this is just a reduction in the severity or length of symptoms.
However, the problem with a mass vaccination like this is that it would mean effectively spreading a version of H5N1 through the human population, creating hundreds of millions of potential hybridisation vectors, should the H5N1 vaccine itself produce undergo hybridisation within a human host. Also, manufacturing huge quantities of vaccine necessitates cultivation of H5N1 at dozens of sites and this itself presents some risk of contamination.
posted by meehawl at 9:10 AM on October 23, 2005
Some countries are advocating widespread vaccination with some variation of this strain as a prophylactic.
There are, however, several problems with this. The first is that if and when H5N1 mutates into a pandemic strain (either by hybridisation or through internal modification), it is unknown how much if any protection the existing H5N1 vaccines will offer. The virus's protein coat will undoubtedly be significantly modified and it may be divergent enough that antibodies created using the original H5N1 template will fail to recognise the new pathogen.
There are those that say, to hell with this, let's just vaccinate anyway and hope that some or many people get at least some moderate protection, even if this is just a reduction in the severity or length of symptoms.
However, the problem with a mass vaccination like this is that it would mean effectively spreading a version of H5N1 through the human population, creating hundreds of millions of potential hybridisation vectors, should the H5N1 vaccine itself produce undergo hybridisation within a human host. Also, manufacturing huge quantities of vaccine necessitates cultivation of H5N1 at dozens of sites and this itself presents some risk of contamination.
posted by meehawl at 9:10 AM on October 23, 2005
As others have said, no. Sort of.
It depends what you mean. Is will the flu vaccine help you if you're exposed to avian flu? No.
However... The regular flu vaccine could be enormously helpful in preventing or delaying an avian flu pandemic. As others have mentioned, the start of a pandemic will require that the current version of the avian flu mutate in a way that makes it easily transmissable between humans. One of the ways the virus mutates is by infectnig people who are already infected with another flu virus. The two viruses mix up their gene pools and if we're not so lucky, they come out with the deadliness of avian flu and the transmissability of the regular flu.
Therefore, we can make it less likely that the virus will mutate (in that way) in any given person by ensuring that the people who are exposed to avian flu are less likely to be infected with other flu viruses at the same time. In fact, this is one of the steps that being taken by some places. Of course it would help if poultry workers everywhere were protected.
Once the pandemic hits, presumably the virus will continue to mutate. I imagine this will make it even more difficulty to develop a vaccine since by the time the vaccine is developped, tested, and produced, there could be a new dominate strain of the virus. So you want to keep the rate of mutation down, even once it's spreading among the general population. Again, the fewer people infected with avian flu and another flu at the same time, the lower rate of mutation you can expect, so in a perfect world everyone would be vaccinated against the regular flu when the pandemic hits.
You cannot create a perfect world and make sure everyone is vaccinated. You can get vaccinated yourself, and though it won't change the outcome for you personally, it could make a difference on a wider scale (remember that network effects (and flu is a network phenomena) are highly contingent and small changes can have big effects). Therefore, while it won't save your life, prevent you from getting the avian flu, or anything else, getting the flu shot is still the sociall responsible thing to do.
(It's obviously the socially responsible thing to do even without a pandemic threat, but the consequences are obviously/by definition on a larger scale when you're dealing with a pandemic).
posted by duck at 9:50 AM on October 23, 2005
It depends what you mean. Is will the flu vaccine help you if you're exposed to avian flu? No.
However... The regular flu vaccine could be enormously helpful in preventing or delaying an avian flu pandemic. As others have mentioned, the start of a pandemic will require that the current version of the avian flu mutate in a way that makes it easily transmissable between humans. One of the ways the virus mutates is by infectnig people who are already infected with another flu virus. The two viruses mix up their gene pools and if we're not so lucky, they come out with the deadliness of avian flu and the transmissability of the regular flu.
Therefore, we can make it less likely that the virus will mutate (in that way) in any given person by ensuring that the people who are exposed to avian flu are less likely to be infected with other flu viruses at the same time. In fact, this is one of the steps that being taken by some places. Of course it would help if poultry workers everywhere were protected.
Once the pandemic hits, presumably the virus will continue to mutate. I imagine this will make it even more difficulty to develop a vaccine since by the time the vaccine is developped, tested, and produced, there could be a new dominate strain of the virus. So you want to keep the rate of mutation down, even once it's spreading among the general population. Again, the fewer people infected with avian flu and another flu at the same time, the lower rate of mutation you can expect, so in a perfect world everyone would be vaccinated against the regular flu when the pandemic hits.
You cannot create a perfect world and make sure everyone is vaccinated. You can get vaccinated yourself, and though it won't change the outcome for you personally, it could make a difference on a wider scale (remember that network effects (and flu is a network phenomena) are highly contingent and small changes can have big effects). Therefore, while it won't save your life, prevent you from getting the avian flu, or anything else, getting the flu shot is still the sociall responsible thing to do.
(It's obviously the socially responsible thing to do even without a pandemic threat, but the consequences are obviously/by definition on a larger scale when you're dealing with a pandemic).
posted by duck at 9:50 AM on October 23, 2005
Just to address a few responses so far:
- Avian flu (H5N1) and most of the "regular" flu strains are Influenza type A. This winter's flu shot will protect against at least two types of type A, but also a Hong Kong strain of Influenza type B, which I've heard is pretty nasty. If you're not immune-compromised, nor live in a household with someone who's immune-compromised, you may want to look into getting the FluMist instead of the flu shot. FluMist uses live virus squirted up your nose, and not only provides excellent protection against the "regular" flu's, but there's some evidence it may increase your chances of a good antibody recation to avian flu, H5N1, even though it wasn't specifically formulated against H5N1.
- Tamiflu is not a vaccine, it's an anti-viral drug. (The media keeps screwing this up in their reports, and it's really annoying.) It can work both as a treatment, if taken within 48 hours of a person's known exposure to the flu, and as a prophylaxis against getting the flu in the first place. But to do the second, you'd have to take a pill twice a day everyday until the pandemic is over. And people like Michael Osterholm at CIDRAP are publically stating than a pandemic coudl last for 12-18 months. That's a lot of Tamiflu. And the flu may become resistant to it anyway; one type of avian flu (the Vietnamese strain from last year) was resistant, but most of the Jakarta cases are still being helped by it, thankfully.
- There have been about 110 people known to be infected with avian flu and about 61 of them have died. It's possible that there are more people, maybe in rural areas of Vietnam or Indonesia or other areas with lack of health coverage, who had minor cases and recovered, thus making the fatality rate seem worse than it really is. But it's equally likely that a number of human cases, including fatalities, were covered up in China earlier this year (Google on "Qinghai Lake" or "S. Suis") and a lot of cases are thought to be misdiagnosed as dengue fever, just as happened in 1918.
- Most distrubingly of all, there have been cases of human-to-human (H2H) transmission. It's just that they are not sustained H2H chains. There have been a few cases of families in Indonesia (most recently, one this week) where the onset of symptoms among family members was staggered, and only one of the family members had any contact with poultry, strongly suggesting H2H within the household. In one of the cases in Jakarta a few months ago, no one in the (middle-class civil service) family had any contact with poultry, and yet the father and later his two daughters all got sick somehow. And one health care worker (nurse, I think) who was treating bird flu patients got sick. If you read carefully the words of the CDC and WHO officials, they're now saying there's no evidence of "efficient" or "sustained" H2H. But it does exist.
posted by Asparagirl at 12:59 PM on October 23, 2005
- Avian flu (H5N1) and most of the "regular" flu strains are Influenza type A. This winter's flu shot will protect against at least two types of type A, but also a Hong Kong strain of Influenza type B, which I've heard is pretty nasty. If you're not immune-compromised, nor live in a household with someone who's immune-compromised, you may want to look into getting the FluMist instead of the flu shot. FluMist uses live virus squirted up your nose, and not only provides excellent protection against the "regular" flu's, but there's some evidence it may increase your chances of a good antibody recation to avian flu, H5N1, even though it wasn't specifically formulated against H5N1.
- Tamiflu is not a vaccine, it's an anti-viral drug. (The media keeps screwing this up in their reports, and it's really annoying.) It can work both as a treatment, if taken within 48 hours of a person's known exposure to the flu, and as a prophylaxis against getting the flu in the first place. But to do the second, you'd have to take a pill twice a day everyday until the pandemic is over. And people like Michael Osterholm at CIDRAP are publically stating than a pandemic coudl last for 12-18 months. That's a lot of Tamiflu. And the flu may become resistant to it anyway; one type of avian flu (the Vietnamese strain from last year) was resistant, but most of the Jakarta cases are still being helped by it, thankfully.
- There have been about 110 people known to be infected with avian flu and about 61 of them have died. It's possible that there are more people, maybe in rural areas of Vietnam or Indonesia or other areas with lack of health coverage, who had minor cases and recovered, thus making the fatality rate seem worse than it really is. But it's equally likely that a number of human cases, including fatalities, were covered up in China earlier this year (Google on "Qinghai Lake" or "S. Suis") and a lot of cases are thought to be misdiagnosed as dengue fever, just as happened in 1918.
- Most distrubingly of all, there have been cases of human-to-human (H2H) transmission. It's just that they are not sustained H2H chains. There have been a few cases of families in Indonesia (most recently, one this week) where the onset of symptoms among family members was staggered, and only one of the family members had any contact with poultry, strongly suggesting H2H within the household. In one of the cases in Jakarta a few months ago, no one in the (middle-class civil service) family had any contact with poultry, and yet the father and later his two daughters all got sick somehow. And one health care worker (nurse, I think) who was treating bird flu patients got sick. If you read carefully the words of the CDC and WHO officials, they're now saying there's no evidence of "efficient" or "sustained" H2H. But it does exist.
posted by Asparagirl at 12:59 PM on October 23, 2005
Is regular flu vaccine effective against the avian flu?
This isn't a yes/no question; it's a sliding scale. The CDC says:
Why do I need to get vaccinated against the flu every year?
* Flu viruses change from year to year, which means two things. First, you can get the flu more than once during your lifetime. The immunity (natural protection that develops against a disease after a person has had that disease) that is built up from having the flu caused by one virus strain doesn't always provide protection when a new strain is circulating. Second, a vaccine made against flu viruses circulating last year may not protect against the newer viruses. That is why the influenza vaccine is updated to include current viruses every year.
Another reason to get flu vaccine every year is that after you get vaccinated, your immunity to the disease declines over time and may be too low to provide protection after one year.
Immunity, of course, is also not a black and white thing. It's a level of effectiveness of your immune-system response against an invading virus. If you have had certain types of flu in the recent past your immune system may well do fine against the avian flu. (Note: I am not recommending against vaccination or treatment!) In fact, a large number of people who get any flu experience few symptoms or get over it quickly. The avian flu has probably only spread as far as it has because the virus is not very effective in the human metabolism in the first place -- but once it gets in and survives, hoo boy.
To become a pandemic, a virus will have to master two key things: first, spreading within the host, and second, surviving outside the host long enough to spread. At this point the avian flu is demonstrating a lot more of the first than the second, and the limited sample, as I noted, suggests it isn't really very good at the first either.
Nevertheless, the virus is subject to easy and frequent mutation, so it's constantly trying new variations on itself against different hosts. Eventually it might find a match. That's when we need to worry.
posted by dhartung at 7:28 PM on October 23, 2005
This isn't a yes/no question; it's a sliding scale. The CDC says:
Why do I need to get vaccinated against the flu every year?
* Flu viruses change from year to year, which means two things. First, you can get the flu more than once during your lifetime. The immunity (natural protection that develops against a disease after a person has had that disease) that is built up from having the flu caused by one virus strain doesn't always provide protection when a new strain is circulating. Second, a vaccine made against flu viruses circulating last year may not protect against the newer viruses. That is why the influenza vaccine is updated to include current viruses every year.
Another reason to get flu vaccine every year is that after you get vaccinated, your immunity to the disease declines over time and may be too low to provide protection after one year.
Immunity, of course, is also not a black and white thing. It's a level of effectiveness of your immune-system response against an invading virus. If you have had certain types of flu in the recent past your immune system may well do fine against the avian flu. (Note: I am not recommending against vaccination or treatment!) In fact, a large number of people who get any flu experience few symptoms or get over it quickly. The avian flu has probably only spread as far as it has because the virus is not very effective in the human metabolism in the first place -- but once it gets in and survives, hoo boy.
To become a pandemic, a virus will have to master two key things: first, spreading within the host, and second, surviving outside the host long enough to spread. At this point the avian flu is demonstrating a lot more of the first than the second, and the limited sample, as I noted, suggests it isn't really very good at the first either.
Nevertheless, the virus is subject to easy and frequent mutation, so it's constantly trying new variations on itself against different hosts. Eventually it might find a match. That's when we need to worry.
posted by dhartung at 7:28 PM on October 23, 2005
This thread is closed to new comments.
posted by spork at 11:17 PM on October 22, 2005