a modified yellow fever vaccine的用法和样例：
- For yellow fever vaccine, it is valid for10 years from the day of inoculation.
- a modified yellow fever virus
- For that, it helps to know how the yellow fever vaccine stimulates such potent immunity to begin with, which has been a long-standing mystery.
- The request has been reviewed and accepted by the International Coordinating Group and 1.7 Million doses of yellow fever vaccine will be arriving in Sudan next week.