For some countries, you have to be vaccinated against some diseases such as small pox and yellow fever.有些国家入境时则要求接种一些疾病的疫苗，例如天花和黄热病。
How would you feel if you got a polio, chicken pox, measles, mumps, flu, and small pox at the same time every year?如果你每年的同一时间都要接种脊髓毁质炎，水痘，麻疹，流感的疫苗你会作何感想？”