Children ages 12 to 35 months who receive the DTaP vaccine in their thigh muscle rather than their arm are about half as likely to be brought in for medical attention for an injection-site reaction, according to a study.
For the study, researchers examined the records of 1.4 million children at eight Vaccine Safety Datalink centers across the country.
“These local reactions are the most common side effect of vaccinations,” Lisa A. Jackson, MD, MPH, the studys lead author and a senior investigator at Group Health Research Institute in Seattle, said in a news release. “But we have known relatively little about how to prevent them.”
Local reactions go away after a day or two, but can be painful, and the associated redness and swelling might concern parents, the researchers noted. This study focused on “medically attended” local reactions: those that resulted in a visit to a physician, nurse or ED. Ideally, medically attended local reactions would happen less often than the current rate of nearly one in 100 vaccinated children.
“Our findings support current recommendations to give intramuscular vaccinations in the thigh for children younger than three years,” Jackson said.
Since 2011, the U.S. Advisory Committee on Immunization Practices has recommended giving intramuscular vaccinations to toddlers ages 12 to 35 months in the thigh muscle (or in the deltoid muscle of the arm only if its big enough), and to children ages 3 and older in the deltoid muscle of the arm. But in practice, healthcare providers tend to vary in their choice of vaccine injection sites for children, with parents sometimes influencing the decision.
The research team also tracked local reactions in children ages 3 to 6 and from intramuscular vaccines other than DTaP, including inactivated influenza and hepatitis A. They found no statistically significant differences between vaccinating in the thigh and arm in the older age group or for the other intramuscular vaccines.
Previous evaluations of local reactions after the fifth DTaP vaccine in children ages 4 to 6 found that vaccination in the thigh was linked to a lower risk of local reactions than was vaccination in the arm. Jackson also led an earlier study that showed that neither ibuprofen (Advil) nor acetaminophen (Tylenol) help prevent local reactions after that vaccine.
The latest study is scheduled for publication in Pediatrics. The study abstract is available at http://pediatrics.aappublications.org/content/early/2013/01/08/peds.2012-2617.abstract.