信使RNA（messenger RNA，mRNA）疫苗属于第三代疫苗，即核酸疫苗，具有细胞内表达速度快、有效性和安全性高、反应速度快、易规模化扩大和极具成本效益比等特点，在近30年中取得了突飞猛进的发展，越来越多的证据表明可以用合理的方法来提高这类现代疫苗的有效性和安全性。2020年暴发的由新型冠状病毒引起的新型冠状病毒肺炎大流行给全世界带来了巨大的灾难，导致了过亿例感染和数百万例死亡，疫苗被认为是阻断传播和控制疾病的唯一希望。在所有的疫苗种类中，mRNA疫苗极快的研发速度和有效性引起了广泛的关注。此综述就mRNA疫苗的体内摄取和抗原表达、固有免疫的作用、适应性免疫的激活、mRNA疫苗递送系统以及注射途径的效应等角度进行阐述，以期为mRNA疫苗的设计提供有价值的参考。

Messenger RNA (mRNA) vaccine belongs to the third generation vaccine, namely nucleic acid vaccine. It has the characteristics of high effectiveness and safety, fast reaction speed, easy scale-up and high cost-effectiveness. Rapid advances have been made in the last 3 decades, and the growing body of evidence will enable us to use reasonable methods to improve the effectiveness and safety of these modern vaccines. In 2020, the outbreak of COVID-19 resulted from novel coronavirus infection brought great disaster to the world, causing over 200 million cases and millions of death, and vaccines are considered to be the only hope for blocking transmission and controlling the disease. Among all kinds of vaccines, the rapid development speed and effectiveness of mRNA vaccines have attracted wide attention. This review focuses on the biological distribution of mRNA vaccine, the localization of antigen expression, the role of innate immunity, the activation of adaptive immunity, the delivery system of mRNA vaccine and the effect of injection pathway, so as to provide valuable reference for the design of mRNA vaccine.