MMWR Morb Mortal Wkly Rep. 2015 Jan 16;64(1):10-5.
In the United States, annual vaccination against seasonal influenza is recommended for all persons aged ≥6 months. Each season since 2004-05, CDC has estimated the effectiveness of seasonal influenza vaccine in preventing medically attended acute respiratory illness (ARI) associated with laboratory-confirmed influenza. This season, early estimates of influenza vaccine effectiveness are possible because of widespread, early circulation of influenza viruses. By January 3, 2015, 46 states were experiencing widespread flu activity, with predominance of influenza A (H3N2) viruses. This report presents an initial estimate of seasonal influenza vaccine effectiveness at preventing laboratory-confirmed influenza virus infection associated with medically attended ARI based on data from 2,321 children and adults enrolled in the U.S. Influenza Vaccine Effectiveness Network (Flu VE) during November 10, 2014-January 2, 2015. During this period, overall vaccine effectiveness (VE) (adjusted for study site, age, sex, race/ethnicity, self-rated health, and days from illness onset to enrollment) against laboratory-confirmed influenza associated with medically attended ARI was 23% (95% confidence interval [CI] = 8%-36%). Most influenza infections were due to A (H3N2) viruses. This interim VE estimate is relatively low compared with previous seasons when circulating viruses and vaccine viruses were well-matched and likely reflects the fact that more than two-thirds of circulating A (H3N2) viruses are antigenically and genetically different (drifted) from the A (H3N2) vaccine component of 2014-15 Northern Hemisphere seasonal influenza vaccines. These early, low VE estimates underscore the need for ongoing influenza prevention and treatment measures. CDC continues to recommend influenza vaccination because the vaccine can still prevent some infections with the currently circulating A (H3N2) viruses as well as other viruses that might circulate later in the season, including influenza B viruses. Even when VE is reduced, vaccination still prevents some illness and serious influenza-related complications, including thousands of hospitalizations and deaths. Persons aged ≥6 months who have not yet been vaccinated this season should be vaccinated, including persons who might already have been ill with influenza this season.
在美国，建议所有≥6 个月大的人每年接种季节性流感疫苗。自 2004-05 年以来，CDC 每年都会估计季节性流感疫苗在预防与实验室确诊流感相关的有医疗记录的急性呼吸道疾病（ARI）方面的有效性。由于流感病毒的广泛和早期传播，本季可能会对流感疫苗的早期有效性进行估计。截至 2015 年 1 月 3 日，46 个州都出现了流感广泛流行的情况，主要是甲型 H3N2 流感病毒。本报告根据美国流感疫苗效果网络（Flu VE）在 2014 年 11 月 10 日至 2015 年 1 月 2 日期间登记的 2321 名儿童和成人的数据，初步估计了季节性流感疫苗在预防与有医疗记录的 ARI 相关的实验室确诊流感病毒感染方面的效果。在此期间，针对与有医疗记录的 ARI 相关的实验室确诊流感的总体疫苗有效性（VE）（经研究地点、年龄、性别、种族/族裔、自我报告的健康状况和从发病到登记的天数调整）为 23%（95%置信区间[CI] = 8%-36%）。大多数流感感染是由甲型 H3N2 病毒引起的。与前几个季节相比，这种临时 VE 估计相对较低，当时循环病毒和疫苗病毒匹配良好，这可能反映出一个事实，即超过三分之二的甲型 H3N2 病毒在抗原和遗传上与 2014-15 年北半球季节性流感疫苗的甲型 H3N2 疫苗成分不同（漂移）。这些早期的低 VE 估计强调了持续采取流感预防和治疗措施的必要性。CDC 继续建议接种流感疫苗，因为疫苗仍可以预防当前循环的甲型 H3N2 病毒以及本季晚些时候可能循环的其他病毒引起的一些感染，包括乙型流感病毒。即使 VE 降低，接种疫苗仍可预防一些疾病和严重的与流感相关的并发症，包括数千例住院和死亡。本季尚未接种疫苗的≥6 个月大的人应接种疫苗，包括本季可能已经患有流感的人。
