Policies that require health care workers to receive influenza vaccinations might be based on flawed research, according to a study published Friday in PLOS One.
Flu shot policies
According to STAT News' Helen Branswell, mandatory flu shot policies for health care workers vary significantly by facility and geographic location. In some cases, workers have been fired for refusing the vaccination.
For example, Melanie Swift, an associate professor of clinical medicine and director of Vanderbilt University's occupational health clinic, said health care workers at the organization who refuse to be vaccinated for the flu are suspended without pay. Providers who refuse the vaccine are locked out of the university's information system, meaning they cannot enter information in patients' charts, conduct research, or bill for their time.
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According to Branswell, workers have challenged some of the policies, as well as resulting firings, before labor tribunals and courts. Employers defending the policies typically cite four studies that suggest requiring health care workers to be vaccinated for the flu can help protect patients from contracting the virus, Branswell writes.
Research might be flawed
But a new study suggests the methodology of those studies might be flawed.
The study found that the research employers use to defend the policies was conducted in long-term care facilities, not hospitals.
Further, one of the studies used to defend the policy, which was conducted in Britain, estimated that one flu-related death could be avoided for every eight workers vaccinated. Researchers in the new study said if those estimates were true, then vaccinating the approximate 1.7 million long-term care workers in the United States should prevent about 215,000 flu deaths annually.
However, flu deaths in the United States do not reach those levels. CDC estimates that between 3,000 and 49,000 people of all ages in the United States die from the flu, depending on the strain of the virus and the vaccine's efficacy.
According to the new study, if the British findings were applied to the 5.5 million hospital workers in the United States, there should be 687,500 fewer flu deaths annually in the country.
That number is more than the estimated 675,000 U.S. deaths that occurred during the 1918 Spanish influenza pandemic, which is the worst flu pandemic currently known, Branswell writes.
The study authors wrote, "Some attempt at recalibration of this [number-need-to-vaccinate] is clearly warranted but, surprisingly, has not previously been proposed in the scientific literature."
They concluded, "An intuitive sense that there may be some evidence in support of some patient benefit [for mandatory flu shot policies] is insufficient scientific basis to ethically override individual (health care worker) rights." They continued, "While (health care workers) have an ethical and professional duty not to place their patients at increased risk, so also have advocates for compulsory vaccination a duty to ensure that the evidence they cite is valid and reliable."
But the study authors also wrote that non-vaccination approaches to flu prevention—such as an employee with the flu taking a sick day or wearing a mask at work—seem to be effective at preventing flu transmission.
Michael Osterholm—director of the University of Minnesota's Center for Infectious Diseases Research and Policy who was not involved with the latest study—said the findings do "not refute that vaccination could have some impact on reducing transmission from infected health care workers to patients."
However, study lead author Gaston De Serres of the Quebec Public Health Institute said the new study does "say there is no valid scientific evidence, even now, underpinning enforced health care worker immunizations."
Lisa Jackson, a senior investigator in immunization studies at Seattle's Group Health Research Institute, who also was not involved with the study, agreed. "We can't say what the benefit [of vaccinating health workers] is," she said. "All you can say is these other studies are a gross overestimation."
Andrew Hayward of University College London's Institute of Epidemiology and Health Care, who was the lead author on the British study referenced in the new research, defended his study's findings in a commentary published alongside the new research.
Hayward wrote, "While we claimed that the findings may be generalizable to other settings we did not intend to imply that the extent of the benefit would be similar in other settings." He added, "Indeed we think the effect is likely to be substantially greater in long-term care facilities for frail elderly residents than in the acute care setting or in long-term care facilities catering for less frail patients" (Branswell, STAT News, 1/27; De Serres et al., PLOS One, 1/27; Mongan, McKnight's Long Term Care News, 1/31).
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