By Charnicia E. Huggins

NEW YORK (Reuters Health) - Annual influenza vaccinations seem to protect all adults--not just elderly and other at-risk individuals--during flu season and may also be a money-saving option for employers, new study findings suggest.

Each year, influenza reportedly affects as many as 2 out of every 10 individuals in the United States.

"From this analysis it appears that vaccination of healthy workers is cost saving (in) paying for itself and reducing the frequency of flu," study author Dr. Eric D. Peterson of Duke University Medical Center in Durham, North Carolina, told Reuters Health.

He and his colleagues analyzed previously published data to determine the most cost-effective strategy for preventing and treating the flu in healthy adult workers aged 18 to 50 years. The economic value of the treatment was determined by treatment costs and the number of workdays gained.

Overall, the health benefits of flu vaccination outweighed its associated costs, the investigators report in the August 20th issue of Annals of Internal Medicine.

The best treatment strategy for individuals already infected with the flu bug was vaccination combined with the antiviral drug rimantadine, study findings indicate.

This treatment combination was associated with a cost savings of $30.97 in health benefits, such as workdays gained, compared with nonvaccination and no antiviral treatment, study findings indicate.

Peterson and his team also compared rimantadine with two newer antiviral drugs, to determine if the newer drugs were worth their higher cost.

They found that all of the drugs had health benefits that equaled or exceeded their costs, the report indicates.

Rimantadine was slightly more cost-effective than the newer drugs, yet it was also associated with more frequent nausea and dizziness--side effects known to be more severe in elderly individuals than among healthy workers, the researchers note.

Further, rimantadine is mainly effective against only one type of influenza, according to Peterson.

Taking the newer drugs would require individuals to "trade off a little more cost for newer drugs for their efficacy and fewer side effects," Peterson said. But "if feeling better leads to more days of work, you've more than covered the cost of the drug," he said.

Peterson added that his study did not pit the drugs against each other to determine which drug was the best treatment for influenza.

"Head-to-head trials of various flu treatments need to be done in order to decide which is the best overall," he said.

SOURCE: Annals of Internal Medicine 2002;137:225-231.