1　问题 /条件　疫苗常常是为那些对疫苗安全充满期待的健康人群接种的。接种疫苗后很少发生副反应事件。由于副反应发生率低 ,疫苗试验数量有限或其它研究方面的局限性 ,有些副反应不太可能在认证前期的临床试验中发现。然而 ,疫苗上市后 ,对接种疫苗后副反应事件的监测是很重 1 Questions / Conditions Vaccines are often given to healthy people who are looking forward to vaccine safety. Few adverse events occur after vaccination. Due to the low incidence of side effects, the limited number of vaccine trials or other research limitations, it is unlikely that some side effects will be detected in pre-certification clinical trials. However, post-vaccination surveillance of adverse events following vaccination is heavy