We would have to develop a vaccine or something like it to prevent the spread of the sickness and find a way to cure the affected people somehow. The moral considerations of what would have to be done if there was no cure are beyond grave (pun intended) because the alternative is state-sanctioned genocide on epic scale… it’s only cute in the movies.
In general the same rules would apply as doctors and emergency response workers already have in place for virulent infections – separation and containment of disease-carrying people, antiseptic protocols, production and distribution of medicine, food, water, and shelter – and so on. You have to worry about keeping the un-infected people healthy in times of crisis because a massive pandemic of this sort can strain the health system to the extent that secondary (unrelated) pandemics of conventional diseases (cholera, etc.) can arise in the healthy population.
Depends on how dangerous the zombies were, if they acted by trying to bite you or eat you, or whether the people infected just stood around. If they were the zombies from the movies, the best thing would be to try and round up them, tranquilize them and contain them. However, if it was a large outbreak and the zombies were extremely violent etc, organizing people in the population into groups for survival with weapons and food may be the only answer, as the army can’t be everywhere.
Drug companies would of course, be either working on a cure or a vaccine in the meantime.