According to Slate’s Ed Finn, the shortage of flu vaccine is related to an egg shortage:

The current shortage of flu vaccines has health officials worried about the possibility of a major epidemic. But manufacturers say it will take six months or more to produce additional vaccines. Why does the process take so long?

Because specially purified and fertilized chicken eggs–the kind manufacturers grow the vaccines in–are hard to come by. There are two stages to creating the influenza vaccine each year. First, researchers working with the Food and Drug Administration and the World Health Organization predict which three strains of the flu will hit heaviest in the coming winter. Then, they develop three seed strains–benign versions of each virus for inclusion in the vaccine.

When the seed strains are ready, they need to go forth and multiply. But viruses can’t reproduce on their own: They require a host organism, and that’s where the eggs come in. The FDA sends the seed strains to manufacturers, who inject them into millions of specially purified fertilized chicken eggs (check out this video on the process). Each egg incubates just one of the three seed strains, which replicate themselves vigorously therein. Then the strains are harvested, tested, and blended together to create the season’s influenza vaccine cocktail. All in all, the process can take six months or more.

Who knew?

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James Joyner
About James Joyner
James Joyner is Professor of Security Studies at Marine Corps University's Command and Staff College. He's a former Army officer and Desert Storm veteran. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. Pam says:

    OooooooK…so how much are EGGS IN CHINA????