If infectious people can infect other people, who in turn can infect others, and so on--the pure infection externality--government subsidies to affect private behavior should equally favor preventive and curative activities, if people recover to become susceptible again. Otherwise, other subsidy...

Testing is a potentially important intervention to slow the HIV epidemic in Africa and elsewhere. Some countries in Africa have achieved high levels of testing but most have not. Cost, price, and questions of confidentiality have limited the expansion of testing. It looks possible, however, that...