Vaccination against seasonal influenza is safe and produces a protective immune response in infants as young as 6 to 12 weeks, concludes a study in the February issue of The Pediatric Infectious Disease Journal. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health, a leading provider of information and business intelligence for students, professionals, and institutions in medicine, nursing, allied health, and pharmacy.
Although confirmatory studies are needed, the results suggest that seasonal flu vaccine could be included in the standard vaccinations for infants less than 6 months old, according to Dr. Janet A. Englund of University of Washington, Seattle, and colleagues.
Flu Shots Yield Good Immune Response with Few Adverse Events
In the study, 1,375 healthy U.S. infants were randomly assigned to receive two doses of the standard trivalent seasonal flu vaccine or an inactive placebo vaccine. ("Trivalent" means that the vaccine offers protection against three strains of circulating influenza virus.) The vaccines were given one month apart, in combination with standard recommended vaccines.
With close follow-up, the researchers found no differences in side effects or adverse events between infants receiving the active influenza vaccine versus placebo. In both groups, about 11 percent of infants developed a fever within three days after vaccination. Through one month, serious adverse events related to the study vaccine were rare.
Immunologic tests showed significant antibody responses to seasonal flu vaccine. Nearly half of infants receiving the trivalent vaccine developed protective antibodies against at least two of the three influenza virus strains covered. There was no evidence that influenza vaccine interfered with responses to the other routine childhood vaccinations.