DRUG BUST by Alan Cassels
A flu virus cartoon stares at me from a poster on the back of a Victoria bus, beckoning me to “do the right thing” and get a flu shot. I might find this amusing if our public health officials, in this case, the Vancouver Island Health Authority (VIHA), were as keen at producing evidence about the effectiveness of the flu shot and monitoring its impact, as they are at spending our money to scare us with cartoon characters.
Maybe it’s just me. Maybe I’ve developed some immunity from the bumpf issued by health propagandists. But the cartoon character exhorting me, as part of the growing flu-shot marketing we’ve seen in recent years, is particularly irksome. It makes the flu jab seem fun, even cool. And possibly a selfless thing to do: “I get the shot so I won’t spread my viruses to others,” I hear people say.
How thoughtful. Yet, do we really know how well the shot works? So far, I’m unconvinced. When asked if I get the annual flu shot, my standard answer is: “If the health authority would randomize me, then I’ll be first in line. If they won’t, I won’t. We’ll see who blinks first.”
Randomize? Most of us would agree that it’s a good idea to have science firmly on your side when you are healthy and someone is coming at you with a needle. Randomization is the best way to reduce bias in health research, and if VIHA was keen to show how beneficial its flu campaign actually is, it would randomly give every second person the real flu shot. The others would get a placebo shot. We’d all be “blind” to who got what. By monitoring people over the course of the flu season, VIHA would note those who went on to develop the flu, were hospitalized, missed work, or even died from it. In the spring, we could hold a little “unblinding” party, where the statisticians would announce how much the flu shot benefited people.
The bottom line is that if we are spending tons of money to do preventative stuff, then we need weapons-grade evidence that there is an overall health benefit for the population.
One problem is that many of us develop a variety of nasties each winter, most of which are not influenza. Between August 2004 and March 2005, Health Canada’s flu watch program collected 68,849 laboratory tests for the flu; of these, only 10,319 tested positive for the virus. That’s right, only 15 percent of the people sick enough to be lab tested actually had the flu virus. The majority of people didn’t have the virus, therefore, a flu vaccine would have provided zero protection – nil, nothing, nada, zilch – from whatever it was that made them ill.
Despite the good intentions of the people at VIHA urging us to get a flu shot, I treat much of the information they serve us with a few dashes of suspicion. Typically, we aren’t reminded that the scientists who make decisions in the spring about which dominant strains of virus will be circulating come flu time are actually rolling the dice. And sometimes, like two years ago, they get it horribly wrong.
As to effectiveness, the VIHA is misleading: “If you’re a healthy, working-age adult, a flu shot will give you 70 to 90 percent protection from the flu virus.” Seventy to 90 percent protection? This means that in tests, the vaccine produces antibodies to the flu 70 to 90 percent of the time. It doesn’t mean that it prevents clinical cases of the flu, the kind that makes you stay home feeling yucky, because that type of prevention is typically much lower.
The best place to look for good evidence is from the top, from overviews of all relevant studies, which are also known as meta-analyses. There is no better source than the Cochrane Collaboration (www.cochrane.org), an international organization comprised of teams of scientists and researchers, largely working as volunteers, gathering and systematically examining all good-quality studies ever conducted to see how well a treatment works. Cochrane’s examination of flu vaccines in healthy adults, a body of literature spanning 25 studies and involving 59,566 people, finds that the yearly recommended vaccines lowered overall clinical influenza only by about six percent. Not quite 70 to 90 percent, is it?
But could a flu shot help keep people on the job? The Cochrane Collaboration found that the vaccine reduced absenteeism by only 0.16 days (about four hours) for each influenza episode, a relatively modest effect given that the average flu bout lasts five to seven days. The authors basically concluded: “There is not enough evidence to recommend universal vaccination against influenza in healthy adults.”
What about kids? Some parents might be surprised to hear that the Canadian Pediatric Society recommends that all Canadian kids older than six months of age get a flu shot every year. VIHA recommends flu shots for kids six to 23 months old. Yet, Dr. F. Edward Yazbak, a US pediatrician specializing in vaccine injuries, points out that there is a lack of strong evidence for immunizing young children for the flu. In September 2003, he wrote to the medical journal The Lancet, pointing out that flu vaccine safety studies in children have not been done, and that the manufacturers held unreported safety data that they refused to allow independent scientists to examine. He concludes that without full disclosure of safety data, parents cannot exactly have great confidence in the vaccines.
So there is some evidence of marginal benefit from the flu vaccine, and incomplete evidence of harm from both the vaccine itself and timerasol, a mercury-based preservative. Overall, I’d say we still don’t have enough data to show whether the local annual flu campaign is worth it. And for this, I say, “Let’s collect more data.”
Go ahead. Randomize me. I’m rolling up my sleeve.
Author’s note: The Cochrane Collaboration’s abstracts are free on the web. The full studies, however, are provided for a fee and can only be accessed if you reside in a country such as Australia or the UK, or a province, such as Saskatchewan, that purchases a site licence for the entire citizenry. Despite Cochrane’s incredible value in systematically reviewing health evidence, the Canadian government has thus far refused to buy a site licence, which would cost about 1.5 cents per Canadian, per year.
Alan Cassels is the co-author with Ray Moynihan of Selling Sickness: How the World’s Biggest Pharmaceutical Companies Are Turning Us All Into Patients.