The overwhelming number of studies showing problems have resulted from injection studies involving rates, in which the natural metabolizing impact effect of digestion is bypassed.
The only side effects are swelling and pain at the injection site, but "these are occurring at rates that are expected and usually seen with seasonal influenza vaccine, " Fukuda said.
The clinical trials of the vaccine showed the main side effects being headache and sore arms in a small percent of patients, and those rates were almost exactly the same as those for a sham injection.