Contentious flu vaccine policies at hospitals are based on flawed research, study says

It’s an edict that comes out every autumn in many hospitals: If health care workers don’t get a flu shot, they will face consequences. Some make vaccinations a condition of employment. Others require unvaccinated staff to wear surgical masks near patients for weeks during flu season.

But a new study is calling into question the scientific evidence underpinning these increasingly common hospital policies — and could fuel challenges to the contentious orders.

The study, published Friday in PLOS One, concludes that the research used to justify mandatory flu shots for health sector workers is flawed, and that the policies cannot plausibly produce the benefits that had widely been assumed.

That is not to say that the group of epidemiologists from Canada, Australia, and France behind the new research opposes the flu vaccine.

“I take it myself,” lead author Dr. Gaston De Serres said. “The reason why I do that is I continue to have the impression that it could work. But it’s one thing to say: ‘OK, on a voluntary basis, you get the vaccine despite all its weaknesses,’ and it’s another thing to say, ‘If you don’t get it, you get fired.’”

Mandatory flu shot policies vary across hospitals and geographic jurisdictions. In some cases, staff who have refused vaccinations have been fired.

Dr. Melanie Swift, an associate professor of clinical medicine at Vanderbilt University and director of its occupational health clinic, said a policy that went into effect there last year results in health workers who refuse the vaccine being sent home without pay.

Faculty — in most cases the doctors — who refuse flu shots are locked out of the university’s information systems. They can’t enter information into patients’ charts, can’t do research, can’t bill for their time. “It’s pretty significant,” Swift said.

Swift gets a flu shot and recommends them to others. And she supports mandatory vaccination policies for some conditions, if there’s clear evidence that unvaccinated health workers pose a risk to patients. She does not support such a policy for influenza vaccine, however. “The case is not there for flu,” she said.

Some policies and firings have been challenged in front of labor tribunals or courts. In those cases, employers regularly point to four specific studies to bolster the argument that vaccinating health care workers reduces the risk of vulnerable patients contracting influenza from caregivers.

But the methodology of the studies produced results that don’t stand up to scrutiny, the authors of the new paper said.

None of the studies were conducted in hospitals; all took place in long-term care facilities. One the studies, from Britain, calculated that one influenza death would be averted for every eight staff members vaccinated.

But if that were correct, vaccinating the estimated 1.7 million health care workers employed in long-term care in the United States should prevent 212,500 flu deaths a year among residents. There’s an obvious problem though, the paper noted. Nowhere near that many people die from flu in the US.

The Centers for Disease Control and Prevention estimates there are between 3,000 and 49,000 flu deaths a year in this country, including people of all ages. The death toll varies depending on which strain of flu is causing the most illness and how well-matched the strains in the vaccine are to the viruses making people sick.

If the calculation is applied to the 5.5 million hospital workers, mandatory flu shots should avert 687,500 deaths each year — more than the number of Americans who died in the 1918 Spanish flu, estimated to be 675,000. The Spanish flu was the worst influenza pandemic in known history.

“The study today does not refute that vaccination could have some impact on reducing transmission from infected health care workers to patients. But it clearly shows there’s no well-conducted study that demonstrates that at this time. Our public policy should be guided as such,” said Michael Osterholm, director of the University of Minnesota’s Center for Infectious Diseases Research and Policy, and lead author of a comprehensive report on influenza vaccine.

De Serres, of the Quebec Public Health Institute in Quebec City, said policies on vaccinating health care workers have evolved over the years, from a gut feeling that it would likely do some good to the idea it should and could be demanded of health workers.

“Do we have scientific data supporting that? I think the bottom line of our paper is to say there is no valid scientific evidence, even now, underpinning enforced health care worker immunizations,” De Serres told STAT.

The lead author of the British study that concluded eight vaccinated health workers would avert one flu death defended the work in a commentary the journal published with De Serres’s article.

Andrew Hayward, of University College London’s Institute of Epidemiology and Health Care, argued among other things that the seniors his group studied were getting 24-hour care. In other words, they were the frailest of the frail elderly.

“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. 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,” Hayward wrote.

Paradoxically, the influenza research community has been down a road much like this one before.

Around the turn of the century, studies assessing the impact of vaccination used to routinely estimate that flu shots cut deaths among the elderly during flu season by a whopping 50 percent.

Not flu deaths. All deaths.

It was dogma for a long while. In fact, it was so entrenched that even questioning how preventing influenza could reduce deaths due to other causes was considered heretical. Dr. Lisa Jackson, a senior investigator in immunization studies at Seattle’s Group Health Research Institute, was one of the leading heretics.

She remembers well receiving a 12-page screed from a reviewer when she and others tried to publish their challenge in the Journal of the American Medical Association. Their ideas were likened to declaring the Earth was flat; they were warned thousands of deaths would be on their heads if their paper was published and believed.

The article was published in 2006 and she and her coauthors eventually persuaded the flu world that flu vaccine could not have such a big effect. Now she’s occasionally asked why she had to bother writing the 2006 paper; the findings it debunked, in 2016, seem so clearly flawed.

Jackson agreed with the argument made in this new paper. “We can’t say what the benefit [of vaccinating health workers] is,” said Jackson, who was not among the authors. “All you can say is these other studies are a gross overestimation.”

Swift said the fights over forcing health care workers to be vaccinated are also drawing needed attention from the pressing issue about flu vaccine. “All this is trying to mandate that health care workers take the flu vaccine is well-intentioned, but is taking away resources and the focus on what our main priority needs to be, which is getting a better influenza vaccine.”