Kevin Hartnett points to a study from last August that demonstrated “that in some cases, flu shots can make an influenza epidemic worse, not better”:
The problem is two-fold: First, flu shots have a high failure rate (last year, nearly 4 in 10 flu vaccinations failed to confer the promised immunity); and second, once you think you’re protected, there’s a natural tendency to be a little more cavalier about germs—maybe washing your hands less, or venturing more boldly into crowded public places.
This dynamic—when safeguards like a vaccine or a condom lead people to act more recklessly—is called “moral hazard” by economists and “risk behavior” by epidemiologists, and it explains how public health interventions can have unintended negative consequences. The Northeastern study is based on a computer model that makes assumptions about vaccine effectiveness and behavior patterns, and simulates how diseases spread in a population. With the flu vaccine they find there’s a tipping point: At low-levels of vaccination, riskier health behavior outweighs the benefits of vaccination and actually fuels the spread of the disease.
Hartnett nevertheless recommends getting a flu shot this year. Sy Mukherjee also favors vaccination, noting the hazards the flu still poses:
About 200,000 people are hospitalized and anywhere from 3,000 to 49,000 people die of the flu every year in the United States, according to the Centers for Disease Control. This year’s flu season is shaping up to be particularly harsh, thanks to the return of the H1N1 flu strain, popularly known as “swine flu.” Federal health officials have reported that at least 35 states currently have “widespread influenza activity.” While national numbers on flu-related deaths aren’t available yet, the virus has killed at least 45 people in California alone so far.
The Dish 