I’m confused by how the media is presenting the news on the avian flu. Is that the name of this year’s strain, or is it a whole new concern? The way they show Bush asking phamaceutical companies to up production makes it sound like, perhaps, the media is equally confused. What’s the Straight Dope? - Jinx
No, avian flu is a flu virus which, at the moment, is pretty hard for people to catch. Only people working with overcrowed chickens in affected areas are at risk from catching it right now. The worry is that it will mutate and suddenly become very easy for people to catch. But it’s not the “flu” that the flu vaccine this year will protect against, although it is similar. (That is, it’s a lung infection influenza, not an achy gut nausea “flu”)
I believe that an effective vaccine is not possible unless and until it mutates into a more human-virulent form. If they make a vaccine against it in it’s current form, whatever mutation occurs may make the vaccine useless.
Vaccines currently used are of a more general kind, stuff that isn’t necessarily healthy for you and kills as much as possible that remotely resembles a flu. But there isn’t a proper and effective one yet that targets it specifically and when it gets sufficiently agile among people, it will probably have mutated beyond recognition of whatever mutation we can target now.
The major problem and concern with the Avian flu is that it is a lot more serious than most types of flu we are used to, in that currently 60% that catches it from birds dies, and if it would break out world-wide among people, death tolls of 20 million ore more are likely.
It certainly has me worried.
No, it targets the specific types of flu viruses that are expected to be prevalent in any given flu season, which is why it needs to be changed every year. See http://www.fda.gov/cber/flu/flu2005.htm for this year’s recipe.
But don’t most of the people who catch it have a great deal of exposure to birds, as in working on chicken farms where the birds are all crammed in together? Once out in the wild, a human strain should, I would think, have much less efficient vectors to spread by. Or do the epidemiologists have that in their models already? In short, is this 1918 all over again, or just the swine flu scare of the 70’s redux?
From the CDC website on Avian Flu:
In a nutshell: it’s unusual for a human to get this flu from a bird, but it has happened. When it has happened, it’s fatal 50% of the time. Recently, there have been a few cases where one person has gotten bird flu from another person, but it’s still rare. Scientists are worried that the virus will mutate, making it easier for one person to catch avian flu from another person. If it does so, the 50% mortality rate is very high for a flu.
There is no vaccine for the bird flu yet, but they’re working on it.
The influenza virus’s genome is divided up into several strands, sort of like our chromosomes. If some person out there gets simultaneously infected with the highly dangerous bird flu and a less dangerous but more infective human strain, the two strains could and would mix and match their chromosomes, potentially producing a strain with the lethality of the bird strain and the infectiveness of the human strain. Of course, it could also produce the opposite - a mild strain that’s hard to pass from person to person, but no one’s too concerned about that.
To clarify on this point, the drugs that pharmaceutical companies are being asked to make more of are NOT flu vaccines, which (hopefully) prevent you from getting the flu entirely. They’re drugs that people can take when they realize that they’re coming down with the flu that make the illness less severe.
Influenza virusdiffers from other viruses in that it’s genome contains eight discreet “packets” of RNA. These can mix-and-match with those from other virus making the structure of the virus extremely variable. Usually the strain is just a variant with a mutation in the viral protein coat. This variation is your: “This years flu”.
However, the avian virus also contains these eight packets of genes. Now it is possible to mix these genes in the bird, or the human, but it also possible for a pig to get the viruses, and cause the shuffle. Then the pig can pass that on to human/birds. Thus, the “Swine Flu”.
The 1918 flu, and this particular avian flu, is different though. It seems to have not been a human/avian recombinant, but completely avian. The avian strain is mutating without gaining genes from the human flu. These avian mutations alone are allowing the virus to infect humans. This also is increasing the virulence, as the virus is entirely foreign.
One should take the fifty percent mortality rate with some skepticism, since it is never accurately reported. The actual words in the WHO and CDC reports are that fifty percent of the cases reported have resulted in fatalities. The possibility that each and every case has been reported is slight. People don’t report mild cases of the flu to their doctor, if they have a doctor. While the number of unreported cases is probably not large, the total number of cases is only sixty or so, and each mild case would reduce the mortality rate by more than a percent. Projecting pandemic death rates of fifty percent is highly unlikely, and alarmist.
Tris
“When they’re handin’ out the heartaches, you know you got to have you some.” ~ Juice Newton ~
If I understand correctly (it’s quite unclear) a sentence in an article I just read (translated loosely : France will have by the beginning of 2006 a stockpile of 2 millions doses of vaccines against the H5N1 virus , that shouldn’t be efficient against a pandemic virus), there would be a vaccine available for the current avian flu virus, but, as you aid (and quite logically) mot against a potential mutant form of it that could cause a pandemia.
Or maybe I don’t understand correctly what the author meant.
A vaccine against H5N1 should be good for H5N1 until the vaccine expires. The ‘H’ part of H5N1 is part of the viral envelope, which is protein called the haemagglutinin, of which there are 13 major antigenic types. The ‘N’ part of H5N1 is a protein, called the neuraminidase of which there are nine major antigenic types. So as long as a vaccine is targeting this couplet of proteins (H5N1) it should be at least partially effective against any H5N1 virus.
Hmmm…That would explain why they stokpiled this vaccine, just in case it would actually prove to be effective against a mutated form of the avian flu?
Or is there something I’m still not understanding?
The vaccine will indeed be effective against avian flu. At least effective against the H5N1 avian flu which is currently infecting people in Southeast Asia. So even if the virluence changes as long as it remains an H5N1 your vaccine will be at least partially effective, as your immune system will have created antibodies against the H5 and N1 proteins in combination in the viral envelope.