Tuesday, 17 April 2012

Flu Shots -- Are They Worth It?

It’s fall in New Zealand, so it’s probably no surprise that the annual ads reminding us to get our flu shots (free for anyone over 65, pregnant, or diagnosed with cancer, heart disease or diabetes)[i] have started to run on our television screens. Promoted, apparently, by the National Influenza Specialist Group (NISG) and the Immunisation Advisory Centre (IMAC) in co-ordination with drug giant Glaxo-Smith Kline[ii], they present flu vaccines as a safe, sensible precaution to prevent “a serious disease that is sometimes fatal,” that can “keep you in bed for a week or more,” and that may “infect up to 1 in 5 of us each year.”[iii] So, is flu truly a serious risk to our health, or is this a scare tactic to get us to spend money on an unnecessary and potentially harmful pharmaceutical product? And can flu vaccines do the job?

Influenza, or “flu”, is a viral infection similar to a common cold (but often more severe) that is characterized by chills, fever, a sore throat, headache, muscle pain, fatigue, coughs, and general discomfort. It can be “caught” by aerial transmission (coughs, sneezes) or through contact with contaminated surfaces.  Good hygiene and sunshine reduce the risk of infection[iv].  Flu strains mutate regularly, so one year’s primary virus may be different from the primary virus the next year. In 1918, the “Spanish” flu pandemic may have killed as many as 100 million people, with a mortality rate of 10-20%. Surprisingly, most of those affected were young, healthy adults because that particular flu strain caused healthy immune systems to “over-react.”[v] Usually, it is the elderly and infirm who are most at risk of flu. Around 25,000 people each year die of flu and flu-related complications (usually pneumonia) in the U.S., and 90% of those individuals are over 65.[vi]

Flu vaccinations increase the body’s ability to deal with flu viruses by increasing antibodies. It is difficult, however, to measure how effective flu vaccinations really are because they don’t necessarily prevent catching the flu, they just help the body fight it off, and it is difficult to differentiate between a common cold and the flu if symptoms aren’t severe. Unless before and after blood tests are taken and examined, it is impossible to know how much a vaccine has increased antibodies (how “effectiveness” is measured in most flu vaccine clinical trials).  If the vaccination matches that year’s flu strain well, then it is expected that 50-70% of those who receive the vaccine will have increased protection against that year’s flu strains. If the vaccine for that year isn’t a good match for that year’s strain—and it IS a matter of prediction—then little if any effect can be detected.[vii] One recent Canadian study published in PLoS Medicine examined the 2009 swine flu outbreak data and found that individuals who had received flu vaccines were MORE LIKELY to have contracted swine flu than those who had not been vaccinated[viii].

The “official” line on flu shots is that they rarely cause serious harm and that expected side effects—soreness or redness at the injection site, aching, and a low-grade fever—are of little consequence[ix]. Although it is rare, flu vaccinations can cause Guillain-Barre Syndrome, a serious and progressive nerve disorder where the body’s immune system attacks the body’s own nerve cells; the odds of getting it from your flu shot are about one in a million[x]. A severe allergic reaction—anaphylaxis—is more common (maybe 1 in 10,000[xi]), usually occurring in people who are allergic to eggs (egg products are used in vaccines), and resulting in rashes, hives, swollen throat and/or face, dizziness, and/or heart rate changes. If severe and untreated, an anaphylactic reaction can result in death.  There is also a myth circulating on the internet that past exposure to flu vaccines can increase the risk of developing Alzheimer’s Disease. I have been unable to find a source for this myth, but one study found that exposure to a variety of vaccines including flu shots was correlated with a lowered—not increased—risk of developing Alzheimer’s[xii].

Coincidentally, the New York Times ran a story last week, Drug Data Shouldn’t be Secret[xiii], on the difficulty of accessing data from clinical trials of the anti-influenza drug Tamiflu, manufactured by Roche. Tamiflu is not a vaccine, but is an oral product for amelioration of flu symptoms. Although Roche claimed their drug “reduced the risk of hospitalization, serious complications, and transmission” in 2009, data to prove these claims was not released.  The US government spent some US$1.5 billion building stockpiles of the drug and, if I remember correctly, there was a certain amount of [media generated?] public hysteria that there wouldn’t be enough Tamiflu to go around in the event of a pandemic. The data that WAS released to researchers [the article seems to imply later] showed Tamiflu to be about as effective as aspirin at ameliorating the symptoms of flu. According to the US Food and Drug Administration, Tamiflu “appears to shave a day off influenza symptoms” while [unfortunately] it simultaneously “interfered with the body’s ability to produce antibodies against influenza,” affecting an individual’s ability to fight off future flu infections. Hmm.

Pharmaceutical companies are businesses, and their primary aim is to make money. If they can convince you (or your company, organisation, or government) that getting an annual flu jab is in your best interest, then that is profitable for their business. See my next post for an expansion on this idea, and some more number crunching that's rather disconcerting.

I don’t get an annual flu shot. It seems to me that given the limited and variable (but virtually unmeasurable) efficacy of flu vaccinations, common minor side effects (sore arm, redness, fever), and the [admittedly small] risk of serious major side effects, this is not a product I wish to spend my money on.  Neither my fear of catching the flu nor my belief in the power of this product to protect me is strong enough to convince me that getting a flu shot is a positive consumer choice for me.

See my next post Why we Believe the Hype About Flu Shots.

[i] See  http://www.fightflu.co.nz/can-i-get-a-free-vaccine/ These aren’t truly free, of course, as the government—ahem, that is, we the people through our taxes—pay for them.
[ii] See http://www.fightflu.co.nz/who-is-nisg/ At the bottom on the page they say “IMAC is contracted to co-ordinate a national influenza promotional campaign.” They don’t say who, exactly, is doing the contracting.
[vi] http://www.cdc.gov/flu/about/qa/fluvaccine.htm Also note the 25,000 deaths figure is probably misleading. See my next post.

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