An additional single dose of vaccine should be received by adult travelers going to the developing countries of Africa, Asia, Latin America, the Middle East, and the Indian Subcontinent, and the majority of the newly independent states of the former Soviet Union. This additional dose of polio vaccine should be received only once during the adult years. Persons born in or after 1957 should consider a second dose of measles vaccine before traveling abroad. Yellow fever vaccine is recommended if traveling to certain parts of Africa and South America. Meningococcal vaccine is recommended for travelers to sub-Saharan Africa, especially if close contact with the locals is anticipated, or if travel occurs during the dry season from December through June.
Cholera vaccine is of questionable benefit to travelers of any age.