CDC officials are anticipating a wave a vaccine horror stories, and reminding folks that by sheer coincidence bad things will happen after some people get their flu shots:

As soon as swine flu vaccinations start next month, some people getting them will drop dead of heart attacks or strokes, some children will have seizures and some pregnant women will miscarry.

But those events will not necessarily have anything to do with the vaccine. That poses a public relations challenge for federal officials, who remember how sensational reports of deaths and illnesses derailed the large-scale flu vaccine drive of 1976...

There are about 2,400 miscarriages a day in the U.S.,” said Dr. Jay C. Butler, chief of the swine flu vaccine task force at the federal Centers for Disease Control and Prevention. “You’ll see things that would have happened anyway. But the vaccine doesn’t cause miscarriages. It also doesn’t cause auto accidents, but they happen.”

Given the size of the United States population, you could easily compile a huge list of people who had health problems after getting a flu shot. A list of anecdotes, however, is meaningless unless you compare it against the null hypothesis. The null hypothesis is your friend.

But what about the new swine flu H1N1 vaccine? Some of the flu vaccine paranoia this season is being generated by worries about this new vaccine - how has there been enough time to test it for side effects?

It's critical to recognize that the H1N1 vaccine isn't fundamentally different from your regular seasonal flu shot, and has the same risk of side effects. H1N1 is influenza A, not some fundamentally different virus like smallpox. The H1N1 vaccine is made in the same way as the seasonal flu shot. For you aficionados, the basic procedure is this:

Influenza A (H1N1) 2009 Monovalent Vaccine, for intramuscular injection, is a sterile, clear, colorless to slightly opalescent suspension with some sediment that resuspends upon shaking to form a homogeneous suspension. Influenza A (H1N1) 2009 Monovalent Vaccine is prepared from influenza virus propagated in the allantoic fluid of embryonated chicken eggs. Following harvest, the virus is purified in a sucrose density gradient using a continuous flow zonal centrifuge. The purified virus is inactivated with beta-propiolactone, and the virus particles are disrupted using sodium taurodeoxycholate to produce a “split virion”. The disrupted virus is further purified and suspended in a phosphate buffered isotonic solution.

Basically, the flu virus is propagated in chicken eggs, then purified and broken up with detergent. The protein pieces of now-dead virus go into the vaccine, where, once injected into you, they stimulate your immune system to produce antibodies against the viral proteins. The only difference between H1N1 and the regular flu vaccine is that you start the manufacturing process with the H1N1 flu strain.

The FDA has approved several H1N1 vaccines, and some of the first reports are coming out.

So go out and get your flu shots next month. (Just keep in mind that this isn't medical advice - just sensible advice. I'm not your doctor.)

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