The World Health Organization defines public health as 'the art and science of

preventing disease, prolonging life and promoting health through the organized

efforts of society'.

A) Explain why public health can be regarded as a public good.

B) Vaccines are one way to deal with the spread of disease; the success of

vaccination programs depends on a significant proportion of the population being

vaccinated. Despite this, some of the population choose not to be vaccinated.

How would economists explain this behaviour? Explain the welfare implications of

such behaviour, and suggest a way the government could intervene in the market

for vaccinations to achieve a more efficient outcome.