The study, which focused on nursing homes in New Mexico, found that when a facility had between 51 and 75 percent of its health care personnel with direct patient care vaccinated, the chances of a flu outbreak in that facility went down by 87 percent.

"The Centers for Disease Control and Prevention have long recommended that health care personnel in nursing homes get vaccinated against the flu, but we didn't know just how much help these recommendations might be in reducing flu outbreaks among residents," said Aaron Wendelboe of the University of Oklahoma, the lead author of the study. "We found strong evidence to support the CDC's recommendation that to protect residents of nursing homes, health care personnel should be vaccinated annually."

In association with the New Mexico Department of Health, Wendelboe and his team surveyed influenza rates at the state's 75 long-term care facilities during the 2006-2007 and 2007-2008 flu seasons. They then looked for correlations between vaccination rates at each facility and whether there was an influenza outbreak.

While increased vaccination of direct care healthcare workers was associated with fewer flu outbreaks, the study found that vaccination rates among residents did not discourage outbreaks. In fact, higher resident vaccination was correlated with a higher probability of an outbreak. That result was unexpected and hard to explain, the researchers say. "While the explanation is likely multi-factorial, we suspect a large factor is that facilities with high resident vaccination rates may over-rely on the direct protection bestowed by vaccinating the residents and under-value the indirect protection bestowed by vaccinating employees," Wendelboe and his team write.

Despite recommendations by the CDC and the Society for Healthcare Epidemiology of America, vaccination rates among U.S. healthcare workers still hover under 65 percent.

"That vaccinating health care personnel provided more protection to residents than vaccinating residents themselves underscores the importance of these recommendations," Wendelboe said.

Note: If no author is given, the source is cited instead.

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