But not getting side effects isn't a negative, health experts say.
When these people received vaccines, they tended to have stronger reactions, such as fever, to the first dose.
That first time you get the injection, your body is just building up its immunity.
How did pregnant women respond after getting vaccines? Some of the information in this story may have changed after publication.
Why do these vaccines seem to have more noticeable side effects than the flu vaccine? Can dogs have an allergic reaction to a vaccine? Usually 24 to 48 hours, and no more than a few days.
Most of the people who received care felt better after receiving medicine and resting.