The measles vaccine is pretty safe and vaccinating your kid is probably good for the individual (it's definitely good for the society). There are more interest

The measles vaccine is pretty safe and vaccinating your kid is probably good for the individual (it's definitely good for the society). There are more interesting cases where the vaccine is harmful or risky, like the smallpox vaccine. You can construct a scenario where the rational thing for any individual is to opt out of the vaccine if enough of his peers are vaccinated to reduce the risk of an epidemic, but the herd immunity is valuable enough that on the whole, vaccinating everyone improves public health. In that case, should researchers play down the downsides of the vaccine? Should the state play them down? Should doctors recommend vaccination even if statistically speaking it is bad for the health of the individual? Note I don't believe this is the situation with any diseases right now: the measles vaccine is safe enough that vaccination is good for the individual, smallpox vaccination would no longer be good for the herd. However, it's an important hypothetical.