Immune compromised woman dies of measles. Are the unvaccinated legally responsible?

The woman was a resident of Clallam County in which five cases of measles were reported earlier in the year. The county health department issued a bulletin noting that four of the cases had occurred among individuals who were not vaccinated, and the fifth case occurred in a person who had received one dose of an early less effective version the vaccine in the 1970s. The dead woman was apparently in a medical facility at the same time as one of the infected people, but before that individual had developed the telltale rash.

Both the dead woman and the person vaccinated in the 1970s had taken the responsibility to try to protect themselves and others from the disease. It should be fairly easy to identify the measles carrier(s) who crossed paths with both, especially the dead woman who evidently acquired her infection at a local health clinic. What legal responsibility should the unvaccinated individuals (or more likely their parents who refused inoculation) bear in these cases?