Studies Support Flu Vaccine's Effectiveness

Immunization works, and vaccinating kids may help everyone, researchers find.

By Serena Gordon
HealthDay Reporter
Wednesday, December 13, 2006; 12:00 AM

Copyright © 2006 ScoutNews, LLC. All rights reserved.

WEDNESDAY, Dec. 13 (HealthDay News) -- Two new studies provide encouraging news about the flu vaccine.

The first found that even when circulating strains of the virus don't perfectly match those included in that year's immunization, the vaccine still provides protection against flu.

The second study found that a school-based immunization program is an effective way to deliver the vaccine, and vaccinating children appears to protect other non-immunized family members against the flu as well.

"These findings are very reassuring and tell us that this vaccine is doing what we hoped it would be doing," said the senior author of the first study, Dr. Arnold S. Monto, a professor of epidemiology at the University of Michigan School of Public Health in Ann Arbor.

Both studies appear in the Dec. 14 issue of the New England Journal of Medicine.

Every year, as many as 20 percent of all Americans are infected with the influenza virus, according to the U.S. Centers for Disease Control and Prevention. Aside from the muscle aches, fever, headache and general misery that the flu is so well known for, the virus can also cause serious complications, including ear infections, pneumonia and dehydration. About 200,000 people are hospitalized each year due to flu complications, and as many as 36,000 die each year from this viral infection, reports the CDC.

There are numerous strains of the flu virus, and these strains are constantly changing. As a result, the vaccine changes annually. Each year, the seasonal flu vaccine includes what health experts expect will be the three top strains circulating that year. While often quite accurate, the vaccine doesn't always match the strains that end up circulating in any given season.

Estimates of the vaccine's efficacy are based largely on studies done with military personnel in years when the vaccine closely matched the flu going around that year. To better assess what happens on a community level, Monto and his colleagues began a three-year study in the 2004-2005 flu season. The current study includes data from the first year of the study.