The finding came from new research involving 1.4 million children at Group Health and 7 other Vaccine Safety Datalink (VSD) centers throughout the nation and was published in the journal Pediatrics.
"These local reactions are the most common side effect of vaccinations. But we have known relatively little about how to prevent them," explained leading researcher Lisa A. Jackson, MD, MPH, a senior investigator at Group Health Research Institute.
It only takes one or two days for local reactions to disappear, however, the area can be very sore and cause parents to be worried, due to the related redness and swelling.
The report centered on local reactions that were "medically attended" - ones that were seen by a nurse or doctor or taken to an emergency room.
Ideally, local reactions would need medical attention less frequently (about 1 in 100 vaccinated kids) than they currently do.
"Our findings support current recommendations to give intramuscular vaccinations in the thigh for children younger than 3 years," revealed Dr. Jackson.
The U.S. Advisory Committee on Immunization Practices (ACIP) has suggested since 2011 that toddlers between the ages of 12 and 35 months should receive intramuscular vaccinations in the thigh muscle (or in the arm's deltoid muscle only if it's large enough) and kids aged 3 and older should receive the shot in the deltoid muscle of the arm.
However, in practice, health care providers often have different opinions on where to give injections to kids, and parents can have an effect on that choice as well.
Kids aged 3 to 6 years who experienced local reactions from intramuscular vaccines other than DTaP, such as inactivated influenza and hepatitis A, were also observed.
The researchers found that there was no notable difference between vaccinating in the thigh or arm in the older age group or for other intramuscular shots.
Prior assessments of local reactions after the 5th DTaP shot in kids between the ages of 4 and 6 demonstrated a link between vaccination in the thigh and reduced chance of local reactions. DAPTACEL® was licensed by the U.S. FDA for the 5th consecutive dose in the DTaP immunization series for children in 2008.
An earlier study, also conducted by Dr. Jackson, indicated that local reactions cannot be prevented with ibuprofen (Advil) or acetaminophen (Tylenol).
The children aged 1 to 6 who were involved in the study and received intramuscular vaccines from 2002 to 2009 were monitored at the following VSD locations:
- Group Health
- Harvard Pilgrim Health Care in Boston
- Marshfield Clinic in Wisconsin
- HealthPartners in Minneapolis
- Kaiser Permanente Colorado in Denver
- Kaiser Permanente Northwest in Portland
- Kaiser Permanente Southern California in Los Angeles
- Kaiser Permanente Northern California in Oakland
Written by Sarah Glynn