Poor people are vulnerable partially because they do not have any kind of insurance. There are many reasons why insurance for the poor is not largely available, such as restricting regulations, lack of information to assess risk, and lack of effective demand in some parts of the population.
One plausible way to create and expand insurance is simply by providing information on why buying insurance (or micro-insurance) is a good idea. This is more effective in communities where social networks are stronger. See this paper by Cai, Janvry and Sadoulet (August 2012), which makes this point.