"Vaccines are important tools in preventing serious infectious disease across the lifespan, from infancy through adulthood. All health care interventions, however, carry the possibility of risk and vaccines are no exception," said pediatrician and bioethicist Dr. Ellen Wright Clayton of Vanderbilt University, who chaired the institute panel.

Still, the report stresses that vaccines generally are safe, and it may help doctors address worries from a small but vocal anti-vaccine movement. Some vaccine-preventable diseases, including measles, are on the rise..

The review echoed numerous other scientific reports that dismiss an autism link.

But it found convincing evidence of 14 side effects:

-Fever-triggered seizures, which seldom cause long-term consequences, from the measles-mumps-rubella, or MMR, vaccine.

-MMR also can cause a rare form of brain inflammation in some people with immune problems.

-The varicella vaccine against chickenpox sometimes triggers that viral infection, resulting in widespread chickenpox or a painful relative called shingles. It also occasionally can lead to pneumonia, hepatitis or meningitis.

-Six vaccines - MMR and the chickenpox, hepatitis B, meningococcal and tetanus-containing vaccines - can cause severe allergic reactions known as anaphylaxis.

-Vaccines in general sometimes trigger fainting or a type of shoulder inflammation.

There's suggestive evidence but not proof of a few other side effects, including anaphylaxis from the human papillomavirus, or HPV, vaccine and short-term joint pain in some women and children from the MMR vaccine.

On the other hand, the report cleared flu shots of blame for two long-suspected side effects: Bell's palsy and worsening of asthma.

That doesn't mean there aren't other side effects - the review couldn't find enough evidence to decide about more than 100 other possibilities. Some vaccines are just too new to link to something really rare. Another example: Flu shots have long come with a caution about rare, paralyzing Guillain-Barre syndrome, but Clayton said research hasn't settled if that's a coincidence since the disorder is more common during the winter.