Bull World Health Organ. 1969;41(3):651-7.
Antigenic relationships are defined by 2 criteria: distance and symmetry. Viruses within a subtype of influenza A are closely related, with the more junior antigens being superseded in time by senior ones. This phenomenon can be reproduced experimentally. Subtypes are distantly related to one another.Immunity to a junior virus is not readily transformed into immunity to a senior antigen given later (original antigenic sin), whereas senior viruses do not jeopardize the efficiency of junior vaccines given subsequently.It is proposed that future vaccines should contain senior mutants of a strain from the most recent epidemic (prospective vaccines), and no junior antigen.
距离和对称性。甲型流感同一亚型内的病毒密切相关，较新的抗原会随着时间被较旧的抗原取代。这种现象可以通过实验再现。不同亚型之间的关系较远。对较新病毒的免疫力不容易转化为对后来出现的较旧抗原的免疫力（原始抗原罪），而较旧的病毒不会影响随后接种的较新疫苗的效力。建议未来的疫苗应包含来自最近疫情毒株的较旧突变体（前瞻性疫苗），而不包含较新抗原。
