VANCOUVER -- It's possible to immunize nearly all health care workers in a hospital against the flu -- but it often takes a big stick.
It took a mandatory vaccination rule -- backed up by the threat of dismissal -- to reach rates of close to 100 percent in three hospitals, researchers reported at the annual meeting of the Infectious Diseases Society of America here.
A host of other approaches -- including education campaigns, easy access to free vaccine, and peer support -- were able to raise rates markedly, according to Dr. Kristen Feemster of the Children's Hospital of Philadelphia.
Bur despite such programs, "our rates had stagnated at about 90 percent," she said.
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The hospital introduced a mandatory policy last year and saw its vaccination rate jump from 92 percent to 99.3 percent, Feemster said.
The policy allowed for religious and medical exemptions, but only 57 staffers -- out of some 9,300 -- took advantage of that loophole, Feemster said. Another nine, she said, refused to get vaccinated and were dismissed.
Overall, she reported, the move was both popular and seen as coercive: 74 percent of staff who answered a voluntary anonymous questionnaire said they agreed with the mandate, but 72 percent saw it as coercive. On the other hand, 96 percent said the rule was important for protecting patients and staff.
The first institution to enforce such a policy -- Virginia Mason Medical Center in Seattle -- has also seen rates close to 100 percent in the five years since it was implemented, according to Dr. Robert Rakita of the University of Washington.
Despite a legal challenge by the nurses' union, Rakita said, the hospital has maintained an average vaccination rate of 98.1 percent since 2005. Interestingly, although the nurses' union had won a grievance against the policy, 96 percent of the nurses got the flu shot anyway in 2009, he said.
The rates don't reach 100 percent because of the nurses' challenge, he said, and also because medical and religious exemptions are allowed. But all told, in 2009, only 1.1 percent of the staff did not get a flu shot, Rakita reported.
One factor that may play a role in the low rate of exemptions, he said, is that workers who have not had a flu shot are required to wear a mask during the flu season.
A similar policy is in place at the Children's Hospital and Medical Center in Omaha, Neb., according to Dr. Archana Chatterjee of Creighton University School of Medicine, also in Omaha.
It's combined with a stiffly worded form that employees must sign if they wish to be exempted, Chatterjee said. In signing the form, a worker acknowledges that immunization protects patients and other staff, and agrees to wear a mask throughout each shift during the flu season.
The hospital introduced the policy after years of education and outreach, Chatterjee said, that saw immunization rates rise relatively steadily from 46 percent in 1998 to 78 percent, 82 percent and 85 percent in 2006, 2007, and 2008, respectively.
The mandatory policy in 2009, she said, kicked the rate up to 97 percent.
The three studies, taken together, suggest that a mandatory immunization policy may be "the tool that works," according to Dr. Andrew Pavia of the University of Utah, who was not part of the studies but who moderated a press conference at which they were presented.
"If the best, most-dedicated, resource-intensive programs get you into the mid-80s," he said, "we need a better tool."
He added there is "good data" that shows the benefit of immunizing health care workers continues to increase as the proportion goes up, rather than leveling off when the rates reach 80 percent or 85 percent.