… that is the question: Whether ’tis Nobler in the mind to suffer. The Slings and Arrows of public pressure, Or to take Arms against flu infection, …
It’s flu season again, and with that our busiest season of answering the question: Should I get the flu vaccine?
To be clear, the flu vaccine is not within a naturopathic doctor’s scope of practice, and as such, it is not appropriate for us to either prescribe the flu vaccine, or advise a person not to have it.
We do endeavour to be helpful, and offer people the information they need to make an educated decision in matters of health they may be confused by, and in search of some manner of “expert” opinion.
This blog entry is actually in support of a Wellness Wednesday video we posted last week, but because it’s so “numbers heavy”, we decided to lay out the numbers (and our references here so readers can follow-up if they want to learn more).
Let’s get started!
Weighing whether or not to make any health decision based on research is not simple, and the flu vaccine is no exception.
In order to gather this information, I considered the four questions most people are considering (even if unconsciously) when making this (or any) decision:
- What are my risks if I don’t have the flu vaccine?
- How effective is the flu vaccine?
- What are the risks associated with having the flu vaccine?
- Do I have any alternatives?
What are the risks of not having the flu vaccine?
Getting the flu: an unpleasant, but usually short-lived infection that resolves on it’s own.
The worst case scenario is development of “flu-related complications”, which can result in death.
The number of Canadian deaths attributed to flu annually according to Health Canada is 3’5001, but this number is based on computer models, not confirmed cases of flu that resulted in deaths. An investigative report by the CBC in 2012 reported that in 2009 when confirmation of suspected flu cases was mandated in response to H1N1 flu- tracking, the number of confirmed flu-related deaths was 4282.
Considering this range of possibilities, and assuming the population of Canada is 35’000’000, your risk of death from flu is between:
- 0.001% if 428 deaths yearly is an accurate estimate, or
- 0.01% if Health Canada models are accurate
Will having the flu vaccine help me avoid flu infection?
Firstly, there are complexities inherent to reviewing medical research. In the case of the flu vaccine, among the complicating factors:
- The flu virus mutates. As such, a new vaccine has to be prepared annually before manufacturers know which strain of flu will be circulating. As such, some years the flu vaccine will be “well-matched” with the circulating virus, and therefore relatively more effective; and other years it will be poorly-matched, and not particularly effective.
As of 2014, the vaccine had been deemed well-matched in seven of the previous 14 years3.
- There is a technical difference between “efficacy” (how effective a vaccine is in a controlled, experimental setting) and “effectiveness” (how well it prevents infection in practice), and different research will focus on different “outcomes”.
Studies are not always “comparing apples to apples”.
- There is more than one version of the flu vaccine, but in broad terms, there is a vaccine made from “inactivated” (“dead”) virus and one made from “weakened live virus” (called “live attenuated vaccine”).
Again, not an “apples to apples” comparison.
- Much of the research on the flu vaccine is paid for by vaccine manufacturers. Research paid for by manufacturers has been demonstrated to be biased in favour of positive results, a fact known by reviewers of research, but not quantifiable.
To find research findings that are useful for answering this question, I considered three factors:
- Using “review articles”. Because new research is published daily, and studies on the same treatment may have differing and even opposite outcomes from study to study, “review articles” attempt to summarize “the bottom line” for readers.
Creation of a review article involves gathering all available research on a topic, removing studies of poor quality, assigning greater weight to more meaningful studies, and finally producing “a final answer”.
- Referring to review articles that present their final determinations in “number needed to treat” (NNT), which is the most meaningful way to present effectiveness of a treatment.
NNT considers not only the people who benefit from a treatment (which is usually how the media reports on medical research), but also other factors such as placebo effect.
For example, if 95% of patients in a group given a particular treatment recover, it would appear that the treatment is very effective. But, if 90% of patients given placebo also recover, the studied treatment is actually contributing very little to recovery (i.e., it’s only 5% better than doing nothing).
Statistically, NNT for this treatment is 20, meaning the first 19 people receiving this treatment would not benefit from it – 20 people have to receive this “very effective” treatment before anyone actually benefits from it.
In the case of the flu vaccine, the NNT represents the number of people who need to receive the flu vaccine to prevent one case of flu.
In order to prevent one case of flu infection, “this many people” need to be vaccinated:
- Limited information indicates the inactivated flu vaccine is no more effective than placebo in children younger than two years (i.e., the vaccine has no effect)3
- 6 – children younger than six years (using weakened live virus)4
- 28 – children older than six years (using inactivated vaccine)4
- 37 – adults (16 to 65 years), in years the vaccine is well-matched3
- 77 – adults (16 to 65 years), in years the vaccine is poorly-matched3
- 40 – adults older than 65 years3
Vaccination using the flu vaccine also:
- Decreased sick days by 0.5 days (in years vaccine was well-matched)
What are the risks associated with having the flu vaccine?
Common side effects of having the flu vaccine are flu-like symptoms lasting one to two days5.
Rare side effects include life-threatening allergies, and development of an autoimmune condition in which nerves are damaged called Guillain-Barre syndrome5.
Are there alternatives to the flu vaccine?
Well, this is where it gets dicey. Yes and no.
There is no “natural flu vaccine”. A vaccine has a very specific mechanism of action of “pre-raising” antibodies to a specific infection that cannot be replicated by any other known means.
There certainly are other means to prevent flu infection. Hand-washing is considered by public health professionals an uncontroversial “alternative” means of preventing infections, including flu infection.
There are natural medicines that will stimulate general immune system activity that can be similarly used to reduce (all, not specifically flu) infections.
I will discuss these next week (this video and blog entry are already waaay too long).
Yes. If you plan to have the flu vaccine:
- Get it at the beginning of flu season (November or early December) so your body has time to create antibodies before you might encounter the virus. Getting the vaccine at the end of the season in response to late-season advertising will confer limited or no protection during flu season itself.
- Get the “live attenuated” vaccine which is inhaled, not the “flu shot”. Research has demonstrated that the live vaccine is more effective.
Until next week.
- For health professionals: Flu (influenza) [Internet]. Government of Canada. [cited 2016 Dec 5]. Available at: http://healthycanadians.gc.ca/diseases-conditions-maladies-affections/disease-maladie/flu-grippe/professionals-professionnels-eng.php.
- Flu deaths reality check [Internet]. CBC. 2012 Nov 25 [cited 2016 Dec 5]. Available at: http://www.cbc.ca/news/health/flu-deaths-reality-check-1.1127442.
- Kolber MR, Lau D, Eurich D, Korownyk C. Effectiveness of the trivalent influenza vaccine. Canadian Family Physician. 2014;60(1):50. Available at: http://www.cfp.ca/content/60/1/50.full.pdf+html
- Jefferson T, Rivetti A, Di Pietrantonj C, Demicheli V, Ferroni E. Vaccines for preventing influenza in healthy children. Cochrane Database of Systematic Reviews 2012, Issue 8. Art. No.: CD004879. DOI: 10.1002/14651858.CD004879.pub4.
- Seasonal flu shot: questions and answers [Internet]. CDC. 2016 Aug 25 [cited 2016 Dec 7]. Available at: http://www.cdc.gov/flu/about/qa/flushot.htm.
Posted: 2016 December 8