Wired -
Flu virus
All flu vaccines start with flu viruses: genetic
material packaged in an envelope of proteins and fats, studded with yet
more proteins—antigens—that push the body’s immune system into action.
With thousands of possible flu variants out there, the World Health
Organization looks at info from 141 labs around the world to determine
which variants are most likely to circulate each year. Since it can take
more than six months to manufacture the shot, the WHO picks four
strains about nine months before flu season: two A viruses (which can
infect humans and animals, like swine flu) and two B viruses (which
primarily affect humans).
Egg Protein
Manufacturers grow the flu viruses in fertilized chicken eggs—hundreds
of millions every year. Scientists inject the viruses into the allantoic fluid between the embryo and the shell, where the viruses replicate. Then the fluid goes for a spin in a centrifuge, along with layers of sucrose solutions of different concentrations to separate the denser virus from the rest of the egg proteins. Trace amounts of egg can remain in the final shot. Read More
of millions every year. Scientists inject the viruses into the allantoic fluid between the embryo and the shell, where the viruses replicate. Then the fluid goes for a spin in a centrifuge, along with layers of sucrose solutions of different concentrations to separate the denser virus from the rest of the egg proteins. Trace amounts of egg can remain in the final shot. Read More
