流感是一种由流感病毒感染引起的急性呼吸道传染病，每年冬春季在全球范围内有不同程度的流行，造成了严重的社会负担，接种流感疫苗是重要的流感预防策略。长期以来使用的三价流感疫苗由WHO推荐的2个甲型疫苗株（甲型H1N1、甲型H3N2）和1个乙型疫苗株组成。流感乙型毒株的两种株系易发生错配或交差循环感染，从而导致乙型疫苗株的保护率下降、感染发病率和死亡率升高。鉴于以上情况，2012年2月WHO推荐使用包含2个乙型疫苗株的四价流感疫苗，随后国内外多种四价流感疫苗相继获批上市。此文就四价流感疫苗的临床研究进展进行综述。

Influenza is an acute respiratory infectious disease caused by influenza virus infection, which leads to serious social burden due to the global epidemics of different degrees in winter and spring every year. Vaccination is an important influenza prevention strategy. Traditional trivalent influenza vaccine consists of two A vaccine strains (H1N1 and H3N2) and one B vaccine strain recommended by WHO based on current epidemic trends. However, the two B strains are prone to mismatch or cross circulation infection, which leads to the declined protection for strain B and increase of influenza morbidity and mortality. In view of the above situation, in February 2012, WHO recommended the use of quadrivalent influenza vaccines containing two strains of B virus vaccine. Subsequently, a variety of quadrivalent influenza vaccines from several companies at home and abroad have been approved and marketed successively. This paper reviews the clinical trials of quadrivalent influenza vaccine.