目的 分析北京市2017-2018年流感流行季期间发生流感聚集性疫情的中小学校的流感疫苗接种情接况和保护效果,为流感疫苗接种策略提供进一步的科学依据.方法 收集北京市2017年10月-2018年1月期间报告的流感聚集性疫情资料,分析流感聚集性疫情的流行病学特征和流感疫苗接种情况,计算疫苗保护率.结果 北京市2017年10月-2018年1月期间共报告流感病毒导致的中小学校聚集性疫情147起,涉及116所中小学,累计发病2 424例,平均罹患率31.7％.乙型Yamagata系流感病毒为引起聚集性疫情的主导株(88起,59.9％);其中主要发生在小学1～2年级(62起,70.5％).疫情学校的流感疫苗总体接种率(37.5％)低于全市中小学校总体接种率(46.8％).接种率≥50％的学校流感聚集性疫情发生率低于接种率＜50％的学校.疫情班级中,总体流感疫苗保护率为29.3％,对甲型流感病毒疫情保护率为43.6％,对乙型Yamagata系流感病毒疫情保护率为13.2％;小学3～6年级保护率(49.0％)高于小学1～2年级(0.5％).结论 虽然2017-2018年度流感疫苗不包含乙型Yamagata系流感病毒组分,集体接种流感疫苗依然能减少中小学流感聚集性疫情的发生,提高流感疫苗接种率能更有效的降低学校聚集性疫情的发生.“,”Objective To examine the influenza vaccination and protective effectiveness among primary and secondary schools in Beijing where the influenza outbreaks were reported during 2017-2018 influenza season,so as to provide further scientific evidences for the influenza vaccination strategy.Methods The data of influenza outbreaks reported from October 2017 to January 2018 were collected.The epidemiological characteristics and influenza vaccination status were described and the vaccine protection rate was calculated.Results A total of 147 influenza outbreaks in primary and secondary schools were reported,affecting cumulatively 2 424 case in 116 schools.The average incidence was 31.7％.Influenza B/Yamagata-Lineage virus was the predominant strain (88 outbreaks,59.9％),and most of outbreaks occurred among students of grade 1 and grade 2 (62 outbreaks,70.5％) in primary schools.The overall influenza vaccination rate of schools where outbreaks occurred (37.5％) was lower than that of all schools in Beijing (46.8％).Schools with the vaccination rate of ≥50％ had less influenza outbreaks than those with the vaccination rate ＜50％.For classes involving in the outbreaks,the overall protection rate of influenza vaccine was 29.3％,and the protection rate against influenza A virus and influenza B/YamagataLineage virus were 43.6％ and 13.2％,respectively.The protection rate among grade 3 to grade 6 (49.0％)was higher than that among grade 1 and grade 2 (0.5％).Conclusions Even though influenza B/YamagataLineage virus was not included in the vaccine formula of 2017-2018 influenza season,collective influenza vaccination still reduced influenza outbreaks in schools.Elevated influenza vaccination rate should be more effective in decreasing influenza outbreaks in schools.