If you have had a serious reaction in the past, your chance of having another one is high.

Two days later, however, there was a more serious reaction.

No serious reactions have been reported in the first five months of its use, he said.

You might have a serious reaction to the shot, but this is rare.

"It wasn't until everybody came back the next Tuesday before the serious reaction set in."

People who have had a serious reaction to the flu shot in the past.

If your child has had a serious allergic reaction in the past, his or her risk of having another is high.

Very few children have had a serious reaction to this vaccine.

The drugs have given him a serious reaction to sunlight.

He thought, I should be having a serious allergic reaction.