In defense of the flu vaccine

By Dr. Perry Kendall, November 2012

BC’s Provincial Officer of Health responds to last month’s Focus article.

I am writing in response to Alan Cassels’ article “Will a flu shot keep you healthy?” Science advances by asking tough questions and challenging accepted “truths.” It is thus essential to have skeptical thinkers like Alan Cassels, Dr Jim Wright and Dr Tom Jefferson active in the field. Our endeavours are all the richer for the questions and concerns they raise.

And I would like to assure your readers that in fact the issues raised by Alan and others are not new to those in public health who, like me, continue to support influenza vaccination as one of the more effective ways of preventing influenza. Nor have we ignored those issues or those criticisms. There are some very compelling reasons why we continue to promote influenza vaccination and I hope to make that case in the following paragraphs.

I do not believe that we are “facing an uphill struggle,” “fear-mongering,” or being “overzealous.”

Firstly, as Alan notes “the flu can be deadly, it can lead to hospitalizations, pneumonia and sometimes death.”

Canadian authorities cite an annual Canadian influenza death toll of between 2000 and 6000; in the US the figures are between 3000 and 49,000 and the WHO estimates 3 million to 5 million cases of severe influenza illness world-wide. Contrary to popular belief, these deaths are not just in the elderly. A recent United States review identified, on average over the last eight years, greater than 100 annual childhood influenza-related deaths and 43 percent of these were in healthy children with no underlying conditions.

In addition to causing many preventable deaths, influenza and pneumonia are the third most common cause of catastrophic disability in the elderly, behind only stroke and congestive cardiac failure. The elderly, infected with influenza in our facilities, can become very ill and deteriorate so significantly that they are no longer able to return home to care for themselves, but must enter long-term care. And many do die; a recent British Medical Journal editorial supporting mandatory influenza vaccination quoted Enstone’s study showing hospital-acquired influenza infections having a high case fatality rate of 27 percent, due to the number of patients with co-morbidities.

Vaccination of healthcare workers reduces the risk to patients. Healthcare workers are frequently implicated as the source of influenza in healthcare settings and patient mortality and morbidity goes down when healthcare workers are vaccinated. Most of the studies have been in long-term care facilities because of the relative ease of conducting randomized control trials in these settings. This has led to some questioning the benefit of this in acute care, highlighting a Cochrane review that felt better studies were needed. And I would agree, better studies are needed. We will in fact be working with the Michael Smith Research Foundation to evaluate the impact of BC’s healthcare worker policy. This is new information and was not available to me (or Alan) at the time of our interview.

While data certainly are better in long-term care facilities, there are ecological studies such as Benet (BMC Infectious Diseases 2012) showing an effect in acute care. We know vaccine in healthy adults has a high effectiveness in a good match year, and that staff who are vaccinated are less likely to transmit illness. Even in a poor match year we see effectiveness of 30 to 40 percent—not a trivial effect, given that we also know that staff are shedding virus and are infectious for 24 hours before they are symptomatic, and studies in nurses show that about a quarter of them will be infected in a given year and the vast majority will continue to work.

I would also like to comment on the overall safety of the vaccine. I do not know anyone who says that anything is perfectly safe, and while all vaccines are associated with some local reaction in many people, serious side effects of influenza vaccine occur at a rate of between 1/100,000 to 1/1,000,000 recipients. I think it worth noting that serious side effects occur more frequently after influenza infection than after vaccination.

There are clear ethical and patient safety and quality issues involved in the decision to improve healthcare worker vaccination rates. Policies requiring a vaccine or mask, rather than being a “strong arm tactic,” meet the combined ethical responsibilities of putting patients first, first doing no harm and protecting those who can’t protect themselves. These ethical principles, the added responsibilities taken on when deciding to become a healthcare worker, have been at the forefront of support for mandatory influenza policies in journal editorials and organizations such as: Lancet (Vaccination is a duty one assumes in becoming a healthcare provider); British Medical Journal (Flu vaccination must be mandatory in all healthcare workers who have direct contact with patients); National Advisory Committee on Immunization (In the absence of contraindications, refusal of healthcare workers who have direct patient contact to be immunized implies failure in their duty of care to patients); Society for Healthcare Epidemiology of America (For the safety of both patients and healthcare workers, annual influenza vaccination should be a condition of both initial and continued healthcare worker employment and/or professional privileges); American Hospital Association; American College of Physicians; American Academy of Pediatrics; Infectious Diseases Society of America; National Patient Safety Foundation; Health Officers Council of BC.

Very recently, the Centre for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota completed a three-year, 13-member panel review of more than 12,000 articles, documents, transcripts and notes, dating from 1936 to 2012 as part of a Comprehensive Influenza Vaccine Initiative ( .

That review did find that previous observational studies had overestimated the effectiveness of seasonal influenza vaccines. It called for more and better studies and evaluations, and for urgent development of new, “game changing,” influenza vaccines, but concluded that despite the limitations noted, given the impact of influenza—“we believe that influenza vaccination is an important health promotion activity that should be widely encouraged and supported. We can and should maintain this infrastructure and use the best technology currently available (i.e., existing influenza vaccines) to protect the public’s health to the degree possible.”

Even as I value Alan’s critique, I really hope that it does not deter anyone from getting their annual influenza vaccination. I will certainly be getting mine.

However, to answer Alan’s header “Will a flu shot keep you healthy?” The answer is that it will significantly improve your chances of not getting influenza. Should you nevertheless get influenza, it will be less likely to be followed with complications, and very importantly, you will decrease the likelihood of passing your influenza viruses along to someone you care for, or about.

As for keeping healthy, as opposed to getting ill, that is a larger question, and I would be more than happy to write on that at a future date.


Alan Cassels’ feature article in the October 2012 Focus can be found at See this month’s letters section for other responses.

Perry Kendall has been BC’s Provincial Officer of Health since 1999.