乙型流感病毒Yamagata系毒株的消失及其疫苗株更换的思考及讨论

Consideration and discussion on extinction of influenza B/Yamagata virus and switch of vaccine strain

乙型流感病毒B/Yamagata系毒株作为季节性流感病毒,已流行近半个世纪。期间,B/Yamagata系毒株与其他亚型或谱系流感病毒一样,经过不断变异和进化,形成多个流行分支。2014年,世界卫生组织(World Health Organization,WHO)推荐B/Yamagata系3A分支B/Phuket/3073/2013为候选疫苗株,之后,3A分支病毒一直为B/Yamagata系的优势毒株。2020年3月以来,全球再未分离到B/Yamagata系毒株,B/Yamagata系毒株可能已在人间消失。近期,关于去除掉四价流感疫苗中B/Yamagata组分的建议越来越明确。本文回顾了乙型流感及其疫苗株的发展历史,客观分析了B/Yamagata系毒株消失的可能原因,综合描述了病毒学、流行病学、免疫学以及与疫苗免疫相关的社会科学、疫苗生产企业等多学科、多部门的观点,并对防止B/Yamagata系毒株重现提出建议,同时也建议疫苗监管部门和生产企业做好工作计划,为四价疫苗更换为三价疫苗做好充分准备。

Influenza B/Yamagata has been circulating in humans for nearly half a century as a seasonal influenza virus.Like other subtypes or lineages of influenza viruses,B/Yamagata lineage virus has continuously mutated and evolved,resulting in multiple clades.In 2014,World Health Organization(WHO)recommended B/Phuket/3073/2013,a representative virus of B/Yamagata lineage 3A group,as a candidate vaccine virus.Since then,the 3A group virus had been the predominant virus of B/Yamagata lineage.Since March 2020,no B/Yamagata lineage virus has been isolated globally.B/Yamagata lineage virus has been probably extinct.Recently,there is a suggestion that WHO should exclude B/Yamagata component from quadrivalent influenza vaccines.This paper reviews the development history of influenza B and its vaccine strains,objectively analyzes the possible causes of the disappearance of B/Yamagata lineage viruses,and comprehensively describes the perspectives of multiple disciplines and departments,including virology,epidemiology,immunology,social sciences related to vaccine immunization and vaccine manufacturers.It makes recommendations on preventing the recurrence of B/Yamagata lineage viruses,and also suggests that policy making authorities and vaccine manufacturers should make plans and preparations for the replacement of quadrivalent vaccine to trivalent vaccine.