How Flu Vaccines Are Made
Ten years ago, in the midst of the 2009 swine flu pandemic, I wrote about the manufacturing process for the H1N1 flu vaccine. It involves billions of chicken eggs.
The most striking feature of the H1N1 flu vaccine manufacturing process is the 1,200,000,000 chicken eggs required to make the 3 billion doses of vaccine that may be required worldwide. There are entire chicken farms in the US and around the world dedicated to producing eggs for the purpose of incubating influenza viruses for use in vaccines. No wonder it takes six months from start to finish.
The post holds up pretty well because, according to the CDC, this is still the way most flu vaccines in America are manufactured. Here’s a look at pharmaceutical company GSK’s egg-based process:
Two other techniques for making flu vaccines were approved for use in the US in 2012 and 2013 respectively, cell-based flu vaccines:
‘Cell-based’ refers to how the flu vaccine is made. Most inactivated influenza vaccines are produced by growing influenza viruses in eggs. The influenza viruses used in the cell-based vaccine are grown in cultured cells of mammalian origin instead of in hens’ eggs.
A cell-based flu vaccine was developed as an alternative to the egg-based manufacturing process. Cell culture technology is potentially more flexible than the traditional technology, which relies upon adequate supply of eggs. In addition, the cell-based flu vaccine that uses cell-based candidate vaccine viruses (CVVs) has the potential to offer better protection than traditional, egg-based flu vaccines as a result of being more similar to flu viruses in circulation.
NIAID and its industry partners have made progress in moving from both the egg-based and cell-based flu vaccine production methods toward recombinant DNA manufacturing for flu vaccines. This method does not require an egg-grown vaccine virus and does not use chicken eggs at all in the production process. Instead, manufacturers isolate a certain protein from a naturally occurring (“wild type”) recommended flu vaccine virus. These proteins are then combined with portions of another virus that grows well in insect cells. The resulting “recombinant” vaccine virus is then mixed with insect cells and allowed to replicate. The flu surface protein called hemagglutinin is then harvested from these cells and purified.
Both of these new techniques make production quicker, thereby resulting in more effective vaccines because they are more likely to match the strains of whatever’s “going around”.
As a reminder, you should get a flu shot every year in the fall. The CDC recommends that “everyone 6 months of age and older should get a flu vaccine every season with rare exception”, especially those “who are at high risk of serious complications from influenza”. Flu vaccines are covered by your health insurance without copay (thanks, Obama!) and are often available at drug stores without an appointment or a long wait. So go get one!
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