University of California Irvine Medical Center is taking an aggressive approach against the flu, and according to a new study, it’s working.

The hospital raised its employee influenza vaccination rate above 90 percent by shifting from a voluntary vaccination program to one mandating all healthcare workers either get vaccinated or wear a mask at work for the entire flu season.

"In moving to a mandatory program, we found that the majority of vaccine declinations for medical or religious reasons remained small throughout all flu seasons. In contrast, the proportion of declinations for preferential reasons, like philosophical beliefs or fear of needles, markedly decreased," said Dr. Susan Huang, a professor at UC Irvine Medical Center and one of the study's authors.

A five-year study of flu vaccination programs at the hospital is published in the January 2012 issue of Infection Control and Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America.

The mandatory campaign requiring vaccination or wearing a mask while in medical areas began in 2009, raising rates that season to nearly 87 percent vaccinated. During the 2010 season, the mandatory policy was strengthened by the dean of the School of Medicine, who provided lists of non-compliant staff to department chairs and linked compliance with the policy with good-standing department budget allocations.

Nationwide vaccination rates hover at 60-65 percent, and relatively few hospitals have enacted mandatory vaccination programs.

"Our findings suggest that inertia, rather than conscious objection or protest, is a major driver of low vaccination rates," Dr. Huang said. "We hope this finding motivates medical facilities to develop policies to ensure that the safety of patients comes first."