Change at the banks. Major credit cards are widely accepted and at major banks they can be used to get cash advances. ATMs are becoming more popular, especially in the bigger cities, but often they don't accept international credit cards. Health Vaccination against yellow fever is required when arriving from an infected area and over 1 year of age. The actual vaccination should only be considered by those planning stays of more than three months in unsanitary conditions where no medical facilities are available.
Malaria is prevalent in the whole country, also in urban areas.
No or very low risk in Colombo, Nuwara Eliya and the coastal strip from Negombo south to Galle. Government response can be in the form of imposing curfews. If not already inaccessible, it's wise to avoid the northern peninsula, especially Jaffna, most of the eastern provinces and the extreme Southeast. Exercise extreme caution in Colombo, especially the downtown area. It's probably best to minimise the time spent in the capital.