Flu shot mandates rooted in flawed science?

CIDRAP says CDC panel went beyond data

In an apparent attempt to err on the side of patient safety, advisors for the Centers for Disease Control and Prevention made recommendations for influenza vaccination of health care personnel (HCP) that went beyond the scientific evidence and now are the source of mandatory and punitive policies, the Center for Infectious Disease Research & Policy (CIDRAP) charges.1

As described in a recently issued CIDRAP flu report, the CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC) made recommendations that do not appear to be fully supported by the studies cited. In particular, HICPAC was questioned for assigning a 1A ranking — meaning “strongly supported by well-designed experimental, clinical, or epidemiological studies” — to a 2006 recommendation to “offer influenza vaccine annually to all eligible HCP to protect staff, patients, and family members and to decrease HCP absenteeism.”2

Sounds innocent enough, but CIDRAP cited a supporting statement for the HICPAC recommendation that reads: “Vaccination of HCP reduces transmission of influenza in healthcare settings, staff illness and absenteeism, and influenza-related morbidity and mortality among persons at increased risk for severe influenza illness.” HICPAC cited four references supporting that statement, according to CIDRAP.3-6

“In the first study3 cited, the authors did not find a statistically significant reduction in patient mortality associated with HCP vaccination, after adjusting for covariates,” CIDRAP stated in the report. “In the second study,4 the authors concluded that ‘we do not have any direct evidence that the reductions in rates of patient mortality and influenza-like illness that were associated with HCP vaccination were due to prevention of influenza.’ In the third study,5 vaccination did not reduce the episodes of self-reported respiratory infection or the number of days ill with a respiratory infection, but it did reduce the time employees were unable to work because of a respiratory infection. In the fourth study,6 the authors reported reductions in absenteeism and illness among HCP that were not statistically significant. The authors did, however, report serologically confirmed vaccine effectiveness of 88% for H3N2 and 89% for influenza B across three influenza seasons.”

Concluding its analysis of the recommendation and references, CIDRAP states that “since only two of the four studies cited provide some support for the HICPAC statement and the others no support, it is unclear how the quality of evidence in these studies received a category IA evidence grade.”

Moreover, two of the randomized clinical trials cited in support of the HICPAC recommendation were found to be at “moderate risk of bias,” in a separate Cochrane Collaboration analysis,7 CIDRAP added. The authors of that review — Thomas RE, et al — concluded that “both elderly people in institutions and the healthcare workers who care for them could be vaccinated for their own protection, but an incremental benefit of vaccinating healthcare workers for elderly people has yet to be proven in well controlled clinical trials.”

Data does not support LAIV for HCP

The questionable HICPAC recommendation has been subsequently used to support mandatory and punitive policies (i.e., requiring masks for unvaccinated HCP) says Michael Osterholm, PhD, CIDRAP director and lead author of the report.

“We recommend that health care workers get vaccinated,” he says. “It’s a logical conclusion even if the vaccine is only 59% effective in younger adults. It is still better than nothing. But the point is that are these data sufficient to support a mandatory policy that has punitive outcomes if you don’t get vaccinated? I don’t think that is the case.”

In another HCP and patient safety issue, the CIDRAP report also found little evidence to support hospital policies offering live-attenuated influenza vaccine (LAIV) as an alternative to the conventional shot. While the LAIV was found to have an 83% efficacy in children up to seven years old, the CIDRAP report found “a lack of evidence” for protection in adults up to age 59 years – a range that would include most health care workers. Thus offering the nasal vaccine as an option to the traditional vaccine for health care workers is not justified by the data analyzed by CIDRAP.

“Just using common sense, if you really wanted to protect the most people on hospital wards and in nursing homes from serious outcomes from respiratory illnesses, you would mandate that anyone who has any symptoms of respiratory illness not be at work,” Osterholm says. “Because we know that other agents beyond influenza can cause serious morbidity and mortality in hospitalized patients and long-term residents. To me, that is the kind of thing where we should use common sense when we don’t have an abundant amount of data. Right now we don’t have the data to support mandatory policies.”

Nevertheless, mandatory flu immunization policies raise no qualms or ethical conflicts for clinicians like Paul Offit, MD, chief of infectious diseases at the Children’s Hospital of Philadelphia, which began mandating flu shots as a condition of employment in 2009.

“If you didn’t get the flu vaccine in 2009 you were given two weeks of unpaid leave to think about it, and if you still didn’t get vaccinated you were fired,” he says. “We fired nine people in this hospital among the roughly 10,000 health care workers, which is to say anybody who could walk out on the floor or into the rooms, including dietary and environmental services [workers].”

The flu vaccine does not necessarily have to have some irrefutable efficacy to justify mandatory policies, he says.

“Are you less likely to get an influenza if you have gotten vaccinated? Yes,” Offit says. “Are you less likely to transmit that virus if you have been vaccinated? Yes. Do hospitals that have higher rates of vaccination have lower rates of nosocomial transmission? Yes. I don’t have any problem with it. The way I see it is when you work in health care — in our case among a vulnerable population of hospitalized children — you bear some responsibility for their care. We don’t believe in this hospital that it is your inalienable right to catch and transmit a potentially fatal infection. Even if the efficacy is as poor as say 30%, 35% or 40% that is still better than zero percent — which is what you get by not getting vaccinated.”


  1. Osterholm MT, Kelley NS, Manske JM, et al. The Compelling Need for Game-Changing Influenza Vaccines: An Analysis of the Influenza Vaccine Enterprise and Recommendations for the Future. Center for Infectious Disease Research & Policy. Oct. 15, 2012. Available at: http://ow.ly/g0PkJ
  2. Pearson M, Bridges C, Harper S, et al. Influenza vaccination of health-care personnel: Recommendations of the Healthcare Infection Control Practices Advisory Committee (HICPAC) and the Advisory Committee on Immunization Practices (ACIP). MMWR 2006;55(RR-2):1-16
  3. Carman WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomised controlled trial. Lancet 2000;355(9198):93-97
  4. Potter J, Stott DJ, Roberts MA, et al. Influenza vaccination of health care workers in long-term care hospitals reduces the mortality of elderly patients. J Infect Dis 1997;175(1):1-6
  5. Saxen H, Virtanen M. Randomized, placebo controlled double blind study on the efficacy of influenza immunization on absenteeism of health care workers. Pediatr Infect Dis 1999;18(9):779-783
  6. Wilde JA, McMillan JA, Serwint J, et al. Effectiveness of influenza vaccine in health care professionals: A randomized trial. JAMA 1999;281(10):908-913
  7. Thomas RE, Jefferson TO, Demicheli V, et al. Influenza vaccination for health-care workers who work with elderly people in institutions: A systematic review. Lancet Infect Dis 2006;6:273-279