February 2005: The $125-Million Question

Proposed flu immunization of all Canadians is not warranted
February 1, 2005

This flu season so far has been quirkier than most, with more twists and turns than a B-grade slasher movie. We can tell you we are glued to our seats watching Canada’s media have a field day, expending barrels of ink on the ups and downs of this season’s flu saga.

First there was the U.S. vaccine supply-shortage story, dooming millions of Americans to certain illness this winter. Then came the news claiming that we can stretch the vaccination supply by just squirting a little of it under the skin, followed by a Dutch study that says people who get annual flu shots live longer. And just out is a story in the Canadian Medical Association Journal on new research saying that doctors should be recommending the flu shot for every Canadian.

On top of that, ironies abound as American citizens, whose government likes to spurn Canadian-made drugs as “unsafe,” are arriving here in Canada by the busload, trainload and boatload and lining up for the flu vaccine that they can’t get back home.

There’s nothing like making something a teensy bit scarce to drive up its perceived value. In fact, the U.S. seniors arriving here are fuelling the hype and hysteria that is causing thousands more of us to get the shot. Demand in Canada for the flu vaccine has reportedly been 25% higher than it was last winter.

Yet amid the flu frenzy, two very important questions aren’t given much attention: What is an average person’s risk of catching the flu? And what is the ability of the flu shot to actually prevent it?

Those are two pretty vital questions worth examining, seeing as it would cost us Canadian taxpayers as much as $125-million a year to immunize all 32 million of us for the flu.

Despite persistent and scary references to a deadly epidemic ready to sweep the globe, the actual incidence of flu in healthy adults is relatively low. In that recent CMAJ analysis, the authors analyzed more than 18 flu-vaccine trials and reported that the rate of flu is somewhere between 1.3% and 20%. This seems rather low, considering the numbers of colds and other nasty respiratory illnesses many of us get in the winter. But the flu shot does nothing to prevent those other non-influenza viruses from infecting us.

And if we do get the flu shot, how well does it actually work?

The efficacy was reported as somewhere between 0% and 18%, depending on which outcome is being measured: hospitalizations, illnesses, or absent days from work. The kicker is that the efficacy of the flu vaccine we get each year depends wholly on the ability of scientists to predict the previous spring what they think will be the dominant flu strains that year. It’s a crap shoot, a guessing game. And they often get it wrong, as they did in 2003.

Public-health officials in Canada seem to be saying everyone needs a flu shot. We contend that it is possible that both the “disease” caused by influenza viruses and the preventive vaccine regimes pushed on healthy people are so hyped that they border on disease-mongering. We think it’s likely not worth spending $125-million to vaccinate all of us each year for this condition.

After all, how much reduction in absenteeism, hospitalizations, or even deaths will $125-million buy us?

No one really knows the answer. It would probably cost us less than $100,000 to find out. It would be incredibly easy to set up a proper, randomized, placebo-controlled, double-blind study of the flu vaccine, tested on people from all groups: healthy people, the elderly and children.

We need such a trial—because, despite the breathless pronouncements over the flu, there is genuine scientific controversy over immunizing people for something that they probably won’t get and for which the outcomes are uncertain. Like any medical intervention, there are some short-term adverse effects we can predict, and long-term ones we can’t predict.

A recent systematic review of more than 25 studies of flu immunization came to conclusions quite different from those recent front-page headlines would suggest. The internationally recognized Cochrane Collaboration (which accepts no money from the pharmaceutical industry) did a systematic review of all randomized trials studying the effectiveness of influenza vaccination and concluded that the evidence does not support universal immunization of healthy adults.

This study found that the flu shot reduced the incidence of clinical influenza on average by 6%, but there was high variability in effectiveness. There were not enough hospitalizations or deaths in the data to come to any conclusions as to what kind of payback the vaccines are delivering.

So the jury is still out on whether a flu shot for all Canadians would be a good use of scarce health-care dollars.

And here’s our challenge to our public-health agencies eager to see us all vaccinated: Set up the study. Randomize about 10,000 Canadians, and bring on the needle. We’re ready to roll up our sleeves and do our part if it is for a study that will help to answer the $125-million question—but not otherwise.

(Alan Cassels is a drug-policy researcher with the University of Victoria. Jim Wright is a professor in the departments of pharmacology, therapeutics and medicine at the University of British Columbia.)