Monday, June 01, 2020

The prevention paradox

“Should we sacrifice individual freedom for the benefit of the population health? Or should we simply help those who really need it? These are questions that health authorities in all countries struggle with.” These are the first sentences of an article that I came across on the Internet. Today, in a time that the coronavirus rules the world, these questions are extremely relevant. For were all these measures to stop the new virus really necessary? Many countries were locked down in order to bring this new virus to a halt, and although the figures are much higher than in case of a flu pandemic, often the number of victims was much less than initially expected. It looks like a paradox, a prevention paradox: Steps were taken to prevent a calamity that didn’t occur. However, as the Wikipedia explains, this is not a paradox but an example of a self-defeating prophecy. Nevertheless, a prevention paradox does exist and it is also relevant in the corona crisis.

The term prevention paradox was coined in an article in 1981 by the epidemiologist Geoffrey Rose. It is based on the dilemma which strategy to choose in case of a widespread disease: an individual approach or a population approach. Take these examples, which I quote from the World Medical Card website (see Sources below), but which are also often mentioned on other relevant websites:

- An American study found that most alcohol-related harm and injuries occurs among individuals who are not alcoholic and have alcohol consumption habits which are considered normal and not harmful.
- The risk of giving birth to children with Downs syndrome is much higher among women over 40 years of age than among younger women. However, only 13% of children with downs are born from mothers over 40, and 51% of children with downs syndrome are born from mothers under the age of 30, who have the lowest risk.
- Although individuals who are overweight and who do not exercise, are at relatively higher risks of dying from coronary heart disease, there are in absolute quantities far more deaths from this disease among individuals who are not overweight and who have led a life with normal healthy levels of physical activity.

The paradox is then that while the majority of the population has a low risk of a certain disease and a minority has a high risk, the absolute numbers of people who get the disease is much bigger among the low risk group than among the high risk group; therefore prevention measures that concentrate on the low risk group are more effective than measures that concentrate on the high risk group. Of course, nobody wants to say that you must not help people who are hit by a disease, but if your financial or other sources are limited, from a cost-effective point of view it is often better to invest them in prevention than in treatment, or, in other words, it can be more advantageous to invest your means in the low risk group than in the high risk group, since it saves more lives.

This conclusion makes the prevention paradox also relevant for the corona crisis. Again and again you hear: Why all these measures that hit me who is healthy and doesn’t belong to the high risk group? Why then a lockdown that restricts my freedom? In view of the prevention paradox the answer is clear: It is because general restrictions save more lives than individual treatments of corona patients, certainly if the big number of patients would make that the health system breaks down. Moreover, in the end, the economy as a whole may be better well off as well. To quote an example of the Encyclopedia of Public HealthThe widespread wearing of seat-belts has produced benefits to many societies but little benefit to most individuals.” Nonetheless, we all profit.

P.S. On the question whether a general lockdown is allowed, if it restricts individual freedom, of course, also my blog on the trolley problem is relevant ( )

- “Prevention paradox”, Wikipedia,
- “The prevention paradox”, World Medical Card,
- “Prevention Paradox”, Encyclopedia of Public Health,

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