Study: Childhood vaccines are safe, low risk

There are some risks associated with some childhood vaccinations, but overall the evidence shows that vaccines are very safe, according a study published in the July 1 online edition and the August print issue of Pediatrics.

The study, "Safety of Vaccines Used for Routine Immunization of U.S. Children: A Systematic Review," is part of a larger report on the safety of vaccines for adults, adolescents and children funded by the Agency for Healthcare Research and Quality. The report was requested by the Office of the Assistant Secretary of Health (OASH).

Maglione

The researchers found no evidence that the MMR (measles, mumps and rubella) vaccine is linked to the onset of autism, a concern often cited by parents who decline to have their children immunized. “The claim of a vaccine-autism link has been thoroughly discredited,” said lead author Margaret Maglione, a policy analyst at RAND Corporation.

Some childhood vaccines are linked to rare adverse events. Common adverse events are relatively minor, such as redness and pain at the site of an injection, while more serious events are extremely rare.

There was moderate evidence that one potentially serious intestinal disorder, intussusception, is in rare cases associated with vaccines against rotavirus, given to prevent serious cases of diarrhea, according to the study. The incidence of this adverse event ranged from 1 case per 100,000 doses to 5 cases per 100,000 doses depending on brand.

The study also supports earlier findings that the MMR vaccine, pneumococcal vaccine and influenza vaccine (particularly when given along with pneumococcal vaccine) are associated with febrile seizures in children; actual occurrence is very rare.

Gidengil“Our findings should help ease the concerns of parents, healthcare providers and others who are worried about vaccine safety,” said senior author Courtney Gidengil, MD, MPH, physician scientist at RAND Corporation and a pediatrician at Boston’s Children’s’ Hospital

In 2011, the Institute of Medicine (IOM) published a consensus report entitled Adverse Effects of Vaccines: Evidence and Causality. That report evaluated the scientific evidence for adverse events potentially associated with varicella, influenza, hepatitis A, hepatitis B, HPV, MMR, meningococcal, tetanus, diphtheria, and pertussis vaccines.

“We report the IOM findings regarding children and update those findings by identifying and evaluating studies published after the IOM searches,” said Maglione.

The researchers also identify studies and evaluate evidence on pneumococcal, rotavirus, Haemophilus influenzae type b, and inactivated poliovirus vaccines, as these are recommended for children aged 6 years and under and not included in the IOM report.

Sixty-seven studies were included; all utilized active surveillance and had a control mechanism-eligible designs were controlled trials, cohorts comparing a vaccinated with non-vaccinated group, case-control studies, self-controlled case series (SCCS), and observational studies that used regression to control for confounders and test multiple relationships simultaneously (multivariate risk factor analyses). Common sources of data included medical records, health insurance claims, and government registries.  To maintain applicability to the current US context, the researchers excluded studies of vaccine formulations never used or no longer available in the United States.

“The bottom line is that our study shows that vaccines are extremely safe, and that severe adverse effects from these vaccines are rare,” said Dr Gidengil. “Vaccines are considered the biggest public health achievement of the 20th century and this study adds to the substantial body of evidence showing that the benefits clearly outweigh the low risks of side effects.”