From 1992 to 2002, influenza (flu) vaccination rates for adolescents with high-risk conditions increased, yet still the overwhelming majority are not being immunized, researchers warn.

Their findings are based on a look-back at 18,730 teens with high-risk conditions, such as asthma, sickle cell disease, HIV infection, and chronic heart disease, who were enrolled in a large HMO.

From 1992 to 1993, influenza vaccination rates increased significantly from 8.3 percent to 12.8 percent, Drs. Mari M. Nakamura and Grace M. Lee from Harvard Medical School in Boston, found. In 2001, the rates climbed again to 15.4 percent.

However, just 11 percent of teens got a flu shot during every season during the period 1999 to 2002.

Depending on the season, between 45 percent and 55 percent of unvaccinated adolescents had one or more missed vaccination opportunities, which the researchers defined as healthcare visits in the first 4 months of flu season during which an unvaccinated teen did not receive the influenza vaccine.

“The persistence of poor influenza vaccination rates demands a different approach to influenza vaccination for adolescents with high-risk conditions,” Nakamura and Lee conclude. “Universal vaccination may be such a strategy, but issues must be addressed to make universal vaccination feasible.”

SOURCE: Pediatrics November 2008.