Influenza Vaccine (Flu Shot)

History sheds some light re the great concern about influenza. The first mass injection of influenza vaccine was into US military personnel in 1945. Following the 1957-58 pandemic, the US Surgeon General recommended annual flu shots for persons with chronic debilitating disease, seniors, and pregnant women. This recommendation was based upon suboptimal studies of young, healthy military recruits, not high-risk groups. In 1964 the ACIP (the committee which recommends US vaccines) noted the absence of appropriate data, but reaffirmed the recommendation nonetheless. In fact, the original three flu shot campaign populations have been excluded from placebo-controlled randomized US clinical trials since they were first targeted fifty years ago. Why? Because the ACIP supports the unscientific assumption it would be unethical to allow placebo-receiving trial participants to forego a flu shot – and why bother anyway, since most people hadn’t thought to question their recommendations. (Refer to the ‘Introduction’ of the Lancet study, Appendix B of the Oct 2012 CIDRAP analysis. For much more from this analysis, read ‘Flu shot science trashed’ listed below.)

Recent science casts a dubious look at flu shot enthusiasm, especially that for flu shots during childhood and pregnancy. Although it’s said that children need to be vaccinated for their own protection and to prevent them acting as vectors of influenza, studies haven’t proven such results: a 2006 Cochrane Review of studies conducted over a period of 40 years found that, in children under age two, the vaccine was no more effective than a placebo; a 2008 study in Archives of Pediatrics & Adolescent Medicine found that “Use of the influenza vaccine was not associated with preventing hospitalizations or reducing physician visits for the flu in children age 5 and younger”; 2009 research presented at the 105th International Conference of the American Thoracic Society found “children who had received the flu vaccine had three times the risk of hospitalization, as compared to children who had not received the vaccine. In asthmatic children, there was a significantly higher risk of hospitalization in subjects who received the TIV [trivalent inactivated vaccine], as compared to those who did not.”; and the 2011 Lancet study referred to above concluded: “the impact that influenza vaccination in children has on influenza outcomes at the population level remains uncertain.”

Even so, considering the wholehearted official endorsement of flu shots, one could be forgiven for assuming that influenza is a major disease in Canada. FluWatch is a public health program which gathers and reports on the relative incidence of influenza cases throughout the year. Its data come from “sentinel laboratories” located throughout Canada which receive and test samples from patients with influenza-like illness (ILI) submitted by their “sentinel practitioners”.

VRAN Flu-like-Watch

As shown by the table below, influenza comprises only a small percentage of all influenza-like illness. For the last 13 influenza seasons, from the end of August of one year to the end of August the following year, Fluwatch archives show:

Date Tests positive for influenza Total samples tested Percent influenza
13 yr totals and % 189,999 1,563,498 12.2%
2012/2013 31,737 190,376 16.7%
2011/2012 12,191 132,667 9.2%
2010/2011 17,573 140,945 12.5%
2009/2010 39,018 204,247 19.1%
2008/2009 23,376 214,067 10.9%
2007/2008 12,256 124,953 9.8%
2006/2007 8,133 100,864 8.1%
2005/2006 7,422 87,303 8.5%
2004/2005 12,879 101,258 12.7%
2003/2004 11,435 92,998 12.3%
2002/2003 3,517 60,725 5.8%
2001/2002 6,258 58,010 10.8%
2000/2001 4,204 55,085 7.6%


2012/2013 season – See Table 2 at

2011/2012 season See Table 2 at

References for all the other seasons listed in our Flu-like-Watch table are available from

Our Flu-like-Watch table shows that the 2009/2010 flu season produced an unusually high percentage of tests positive for influenza – 19.1% as opposed to an average of 9.6% influenza for the nine pre-pandemic seasons listed. One reason for the increased percentage during the pandemic season could have been the unusual number of young people who were severely affected. If the young had experienced less severe influenza as has been the case in other flu seasons, many would likely not have consulted a doctor and consequently been tested.

And why the relatively high 16.7% influenza during the 2012/2013 season? Several possible reasons come to mind. Recent studies have found that those who’ve previously been vaccinated with seasonal influenza vaccines are subsequently more vulnerable to the influenza A H1N1 pandemic strain. According to Table 2 referenced above, that strain constituted 24% of the 16.7% influenza detections made in the 2012/2013 season (4% H1N1; 12.7% all other influenza strains).

Also, the live virus vaccine, FluMist®, was approved for use in Canada in 2010 and first recommended for use in healthy children and adults, 2-59 years old in Nov 2011. Influenza-like symptoms occurred in a large proportion of the 2-17 year old pre-approval trial participants who received the vaccine. Government funding decisions re FluMist® would not have been made immediately after the recommendation but, by autumn 2012 enough may have funded that its use contributed to the higher influenza detections for 2012-2013.

The Canada Communicable Disease Report (CCDR) for the 2005/2006 influenza season states: “Over the 10 seasons from 1996-1997 to 2005-2006, the percentage of positive influenza tests has been below 10% (range 5.8% to 8.7%) when influenza seasons were typically characterized by mixed influenza A and B activity or a predominance of influenza B activity.”

The CCDR for the 2006-2007 season (available from discusses positive test results for ILI due to non-influenza viruses: “The percent positive for RSV [respiratory syncytial virus] detections for the entire 2006-2007 season (11.5%) was similar to previous seasons (7.1% in 2005-2006 and 9.0% in 2004-2005)…The percent positive for parainfluenza and adenovirus detections for the entire 2006-2007 season (3.4% and 1.9% respectively) were similar to previous seasons (4.0% in 2005-2006 and 2.7% in 2004-2005 for parainfluenza viruses and 2.4% in 2005-2006 and 2.6% in 2004-2005 for adenoviruses”). But what of the 75% of ILI samples in which no influenza virus, RSV, parainfluenza or adenovirus was detected? Was the testing of all those inaccurate or were the samples taken from individuals who’d been incorrectly diagnosed as having ILI? Under the heading, ‘Limitations’, the CCDR for 2006-2007 gives many reasons why Fluwatch test results should be interpreted with caution. However, 75% of results is a lot to be cautious about; it’s likely that most of this unclaimed amount is due to the fact that ILI can be caused by any of over 200 viruses, only four of which the FluWatch labs have attempted to detect!

Further Reading

Prevention and Natural Treatment of Influenza

Concerns about Flu Vaccine During Pregnancy & Childhood

More Articles on Flu & Flu Vaccines

Pandemic Influenza – A Reality or Hype?