Gambling on the Flu Shot

Jan 21, 2020

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

I'm waving a blue magic wand. Suddenly you are in charge of Health Canada. You are told an outbreak of an unusual disease is about to hit Canada and kill 600 people. You have to decide between two treatment programs. If you choose Program A, a guaranteed 200 people will be saved. If you choose Program B, there's a 1/3 probability that all 600 people will be saved and a 2/3 probability that no one will be saved. Which of the two programs would you choose? If you are like most people, you choose Program A. It seems less risky to save a guaranteed 200 people than to risk a 2 out of 3 chance no one will be saved.

Let's go back to reality. I unwave the blue wand, and you are back in the Parkland and everyone is talking about the flu. The news says at least two young people in Manitoba have died from flu complications. The flu (or influenza) is a highly contagious viral illness. It can spread easily from one person to another through coughing, sneezing or sharing food and drinks. You can also get the flu by touching objects contaminated with flu virus and then touching your mouth, eyes or nose. That is why hand washing is so important to prevent the spread of the flu. It is also recommended that you cough or sneeze into your elbow, sleeve or into a tissue. Influenza symptoms include fever, headache, cough, muscle aches, runny nose, sore throat and exhaustion. The symptoms of the flu are usually more severe than that of a cold. The onset of the flu is usually quite sudden. Flu symptoms usually last from 7 to 10 days, but the cough and weakness can continue for 6 weeks. Influenza arrives in Manitoba every year in late fall or early winter.

Back in October the public health people, pharmacists and a bunch of others started telling you to get the flu shot. We said it would save lives and save people from getting sick. And many people listened. The people who listened thought the flu shot was a safe, non -risky thing to do. And it was. Getting a flu shot is still the best way to avoid getting the flu. And since it takes about 2 weeks for the flu shot to kick in after the injection, getting the shot in October makes sure the shot is working by the time the flu season starts.

This time I'm waving a red magic wand. You're back in charge of Health Canada. Same outbreak is coming. It is an unusual disease that will kill 600 Canadians. You have to decide between treatment programs again. If you choose Program A, 400 people will die. If you choose Program B, there's a 1/3 probability that nobody will die and a 2/3 probability that 600 people will die. Which of the two programs do you favor? Now, odds are you choose Option B. The guarantee of a loss of 400 people is overwhelming. You might as well go with the program that at least has a chance of no one dying, right?

The math says the blue wand and red wand problems are identical. But they feel very different. This is actually a famous problem, which Amos Tversky and Daniel Kahneman presented to volunteers in the 1970's. Kahneman and Tversky used this and other experiments to show that people choose riskier bets when making decisions that involve losses rather than gains. They called this Prospect Theory. This and other work won Kahneman the Nobel Prize in Economics in 2002.

Prospect Theory explains why people make riskier, "long-shot" bets at the end of the night at the casino, if they are down money. At the beginning of the night, the person was trying to win money. They were focusing on gains and made conservative bets. At the end of the night, they are just trying to break-even. They are focusing on their losses and are making riskier bets.

What does this have to do with flu shots? I always wonder why some people come in for the flu shot in October, and some wait until January. We know the flu shot is more effective the earlier you take in the flu season. That is why all the push to get people to come in October. Were the late comers lazy, not around, or too busy in October? I think it might be Prospect Theory. Maybe the October people were looking at trying to "gain" good health and they thought of flu shots as a conservative or safe bet. The January people seemed to be swayed by the tragic death of at least two young people in Manitoba from flu complications. I think the January people are thinking about losses, like the loss of life. The January people think the flu shot is risky, but now, thinking about potential losses, they are more likely to make risky bets. The flu shot was incredibly safe in October. It is incredibly safe in January. And it is not too late to get one. If you haven't gotten one, come down to the pharmacy today.

At the end of the night at the casino, it is not a good financial strategy to count your losses and make riskier bets to try to break even. But maybe we can use that tendency of people who are counting losses to make riskier bets for good. Hey, if you are worried about the recent deaths due to flu in Manitoba, do something you've never done before. Come down to the pharmacy and get a flu shot! It really is a safe and effective bet, but if anyone asks, tell them it's the riskiest thing you've ever done.

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

As always if you have any questions or concerns about these or other products, ask your pharmacist.

Choiceology with Katy Milkman talking about Prospect Theory -

Manitoba Health's Flu Info Site -


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