Trivalent influenza vaccine safe in young children.

2003 JAN 1 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - The trivalent, cold-adapted influenza vaccine (CAIV-T) was safe in children from 15 months to 6 years old, causing only mild transient symptoms with the first dose, according to a report in the journal, Pediatrics.

Pedro A. Piedra at Baylor College of Medicine and colleagues throughout the U.S. conducted a double-blind, placebo-controlled trial at multiple centers comparing the effects of CAIV-T vaccine delivered by nasal spray to placebo in young children.

In the first year of the trial (1966-1967), 1602 children, aged 15-71 months, were randomly assigned to receive one (n=288) or two doses (n=1,314) of the vaccine or placebo. The following year, 1358 of the subjects received one dose based on their original cohort assignment. In 1998-1999 and 1999-2000, the study became an open-label trial of CAIV-T safety, with 642 and 549 children, respectively, receiving one dose annually.

In the first year of the trial, gastrointestinal symptoms occurred within 10 days after vaccination in approximately 6% of the CAIV-T group and 3.6% of the placebo group.

"CAIV-T seemed to be associated with a mild excess in abdominal pain and vomiting only with the first vaccine dose," reported Piedra and his associates.

Other symptoms significantly associated with the first dose of vaccine included runny nose or nasal congestion, muscle aches, and fever. Only a runny nose was significantly associated with a second dose of the vaccine.

"In year 2, CAIV-T did not cause excess in any of the specific respiratory and gastrointestinal symptoms," Piedra and his collaborators said. "In years 3 and 4, specific respiratory and gastrointestinal symptoms were comparable to that observed in year 2."