Saint Louis University Health Science Center, St. Louis, MO 63104, USA.
Vaccine. 2010 Feb 25;28(9):2149-56. doi: 10.1016/j.vaccine.2009.11.068. Epub 2009 Dec 8.
Seasonal influenza vaccines, including live attenuated influenza vaccine (LAIV), contain three vaccine strains (two type A and one type B). Ideally, the hemagglutinin antigens of the recommended vaccine strains are antigenically similar to epidemic wild-type strains; in actuality, the antigenic match between circulating and vaccine strains each year can vary significantly owing to intermittent genetic reassortment and continuous antigenic drift. For influenza B, antigenic relatedness is further complicated by the existence of two distinct lineages. Consequently, the influenza B vaccine component can be of a completely different antigenic lineage from the circulating epidemic strains. Using data from nine randomized clinical trials in young children (6 months to 6 years of age), vaccine efficacy of LAIV against influenza B strains was assessed across this spectrum of antigenic relatedness. In an integrated analysis, vaccine efficacy of two doses of LAIV in vaccine-naive children was 86% against B strains of the same lineage and closely matched to the vaccine strain, 55% against strains of the same lineage but antigenically drifted from the vaccine strain, and 31% against strains of the opposite B lineage and antigenically unrelated to the vaccine strain. These data provide a more accurate assessment of the protection provided by the current trivalent vaccine and highlight the need for vaccination strategies that provide enhanced protection against both lineages of influenza B such as a quadrivalent influenza vaccine.
季节性流感疫苗，包括减毒活流感疫苗（LAIV），含有三种疫苗株（两种甲型和一种乙型）。理想情况下，推荐疫苗株的血凝素抗原与流行的野生型株在抗原性上相似；实际上，由于间歇性基因重组和持续的抗原漂移，每年流行株与疫苗株之间的抗原匹配差异很大。对于乙型流感，由于存在两个不同的谱系，抗原相关性更加复杂。因此，流感 B 疫苗成分的抗原性与流行的传染病株完全不同。本研究使用了 9 项针对幼儿（6 个月至 6 岁）的随机临床试验数据，评估了 LAIV 针对乙型流感株的疫苗效力在这一抗原相关谱上的情况。在一项综合分析中，两剂 LAIV 对同系疫苗株的效力为 86%，与疫苗株高度匹配，对同系但抗原性与疫苗株漂移的株的效力为 55%，对相反 B 谱系且与疫苗株无抗原关系的株的效力为 31%。这些数据提供了对当前三价疫苗提供的保护更准确的评估，并强调需要采取疫苗接种策略，提供对流感 B 两种谱系的增强保护，例如四价流感疫苗。
