Vaccines have low risk of serious side effects: study

WASHINGTON: Some childhood vaccines are linked to serious side effects, but they are quite rare and do not include autism, food allergies or cancer, said a review of scientific literature Tuesday.

A host of vaccines commonly given to children under age six were the focus of the systematic review of rigorously conducted studies, published in the peer-reviewed US journal Pediatrics.

The report seeks to address a rising trend of vaccine hesitancy among parents in the United States and Europe, which has led to a resurgence of measles and whooping cough in some parts of the world.

"We found that serious adverse events that are linked to vaccines are really rare, and that when they do occur they are often not necessarily severe," said study co-author Courtney Gidengil, a pediatrician at Boston Children´s Hospital and professor at Harvard Medical School.

"We think this adds to the body of evidence that the benefits really do seem to clearly outweigh the low risk of serious side effects from vaccines," she told.

The study expands on a 2011 report by the Institute of Medicine that also pointed to some side effects linked to vaccines but found "few health problems are caused by or clearly associated with vaccines."

The Pediatrics report includes several vaccines that were not studied by the IOM, including those against hepatitis A, Haemophilus influenzae type b (Hib), polio, rotavirus and the pneumococcal conjugate vaccine.

Side effects
Side effects of the measles, mumps and rubella (MMR) and pneumococcal vaccines included the potential for fever and seizures.

The MMR and hepatitis A vaccines were also linked to a side effect called purpura, when small blood vessels leak under the skin.

There was some evidence that immune-deficient children given the varicella vaccine against chicken pox could develop infections or have an allergic reaction.

The rotavirus vaccines, RotaTeq and Rotarix, were associated with a risk of intussusception, a condition in which one part of the intestine slides into another part.

However, the risk of this condition was rare, amounting to between 1-5 in 100,000, the researchers said.

"Clinicians who immunize children regularly may have encountered these adverse events in their practices, particularly seizures associated with fever," said an accompanying editorial by Carrie Byington, vice chair for research in the pediatrics department at the University of Utah.

"Fortunately, the adverse events identified by the authors were rare and in most cases would be expected to resolve completely after the acute event."