How do flu vaccines work?

Nature News ^

[neverdem]

The immune system uses antibodies (that is, proteins that attach specifically to the virus) and T cells (which encourage the production of antibodies and also destroy cells infected with the virus) to clear the virus from the body, but often not before it has been passed on to other people.

Introduction

When a normal healthy person becomes infected for the first time with a particular flu virus, their immune system takes several days to 'recognize' and attack it, by which point it will have multiplied millions of times. The immune system uses antibodies (that is, proteins that attach specifically to the virus) and T cells (which encourage the production of antibodies and also destroy cells infected with the virus) to clear the virus from the body, but often not before it has been passed on to other people.

If a person or animal has a repeat infection with the same strain, the immune defences 'remember' the previous encounter, and mount a stronger and quicker attack, eradicating the virus earlier in its course of infection. The infected person experiences less severe, if any, symptoms and is less likely to pass on the virus (although this cannot be ruled out). Vaccines operate on the same principle — that is, they mimic the presence of the real virus in the body so that the immune defences are 'primed' and ready for rapid action as soon as it appears.

• Related FAQs

  • What is bird flu?
  • Why is bird flu more deadly than seasonal flu in humans?
  • Is there a vaccine for bird flu?
  • Why do new flu vaccines have to be made each season?
  • How are flu vaccines made?

• Related External Links

  • Centers for Disease Control and Prevention, Avian Influenza (Bird Flu)
  • Center for Infectious Disease Research & Policy (CIDRAP)
  • Flu Wiki
  • Food and Agriculture Organization of the United Nations, Avian Influenza
  • Nature Reports Avian Flu
  • PandemicFlu.gov, AvianFlu.gov
  • SciDev.Net (Science and Development Network)
  • World Health Organization, Avian Influenza

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[neverdem]

Nature News did a swine flu special.

The short article and links above are just one part of it. From the URL it looks like it's from Nov. 2007.

[neverdem]

The link in comment# 1 goes to a special on swine flu.

[grey_whiskers]

Thanks, dude.

But I'm overdue for the treadmill...

Cheers!

[grey_whiskers]

Note -- it appears that the links under "Related FAQs" (those that try to link to the jounal Nature) -- are broken.

Cheers!

[Smokin' Joe]

ping...(Thanks, neverdem!)

[Myrddin]

The short answer: you grow the real virus or one very close. The virus is then "attenuated" using formaldehyde or heat to reduce its potency while leaving the necessary antigenic sites intact. The immune system recognizes the new antigens as "foreign" and creates a matching "antibody" that can bind to the antigen. When live virus arrives, the immune system makes lots of matching antibody. An antibody-antigen pair provides the necessary means for other immune system cells to envelop and destroy the virus bound to the antibody.

The critical first step is starting with a good sample of the target virus and successfully growing lots of it.

[neverdem]

At least two of the five frequently asked questions(FAQ) have broken links. I emailed Nature about one of them. I missed converting the next link from a relative URL to an absolute URL when I posted the story for the thread. I'm sorry. Check the link in comment# 1 for their Swine Flu special.

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