CNN | January 16, 2004

ATLANTA,Georgia (CNN) -- This year's flu vaccine had little or no effectiveness against influenza-like illnesses, according to a preliminary study released Thursday.

The study, published by the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report, looked at workers at Children's Hospital in Denver, Colorado.

Of the 1,000 people who got the vaccine before November 1, 149 went on to develop influenza-like illness (14.9 percent). Of the 402 people who did not get the vaccine, 68 got an influenza-like illness (16.9 percent), the study said.

This year's outbreak started early and more severely than usual, sparking a run on vaccine by people eager to protect themselves. That depleted supplies.

But the vaccine did not contain the Fujian A virus that proved to be the predominant strain this year. Despite public health authorities' hopes that there was enough overlap with the vaccine's other strains that some protection would be conferred, that does not appear to be the case.

The preliminary findings "demonstrated no or very low effectiveness," against flu or flu-like illnesses, the report stated. But officials said the vaccine is not designed to combat flu-like illnesses.

Still, the epidemic appears to be waning. The disease agency reported widespread flu activity is now found in 20 states, down from 38 states last week and 42 the week before.

In an editorial note, the authors said the vaccine could still prove useful should the flu strains it contains emerge later in the season.

In a typical year, the disease kills about 36,000 Americans.