流感很常见，但是对于免疫力低下的人来说，流感可能是致命的。因为流感病毒容易变异，疫苗就要跟着变，所以每年的流感疫苗都不一样，年年都要重新打。要是有一种不怕病毒变异的流感疫苗就好了。
The quest for a universal flu vaccine
by Andrea Michelson
With the deadly 2017-2018 flu season still fresh in public health officials' minds, this year's outbreak is shaping up to be just as severe. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), says this flu season could be one of the worst in decades.
deadly /ˈdedli/ adj. 致命的、致死的
official /əˈfɪʃ(ə)l/ n. 官员
outbreak /ˈaʊtbreɪk/ n. （疾病、战争等）爆发
shape up = develop
severe /sɪˈvɪə(r)/ adj. 严重的
institute /ˈɪnstɪtjuːt/ n. 学院、研究院
allergy /ˈælədʒi/ n. 过敏
infectious /ɪnˈfekʃəs/ adj. 传染的
decade /ˈdekeɪd/ n. 十年
Last week, the Centers for Disease Control and Prevention (CDC) announced that there have been at least 9.7 million cases of the flu since early October. The CDC has also been tracking flu mortality, reporting at least 4,800 flu-related deaths this season.
prevention /prɪˈvenʃ(ə)n/ n. 预防（由prevent加后缀-ion变成名词）
track /træk/ v. 追踪、跟踪
mortality /mɔːˈtæləti/ n. 死亡数量
related /rɪˈleɪtɪd/ adj. 有关的
Even in mild cases, the flu virus can cause unpleasant symptoms like high fevers, muscle aches and fatigue（疲劳）. To protect yourself against the annual flu outbreak, public health officials have a simple piece of advice: get your flu shot.
mild /maɪld/ adj. 不严重的
virus /ˈvaɪərəs/ n. 病毒
cause /kɔːz/ v. 造成
symptom /ˈsɪmptəm/ n. 症状
high fever 高烧
muscle /ˈmʌs(ə)l/ n. 肌肉
shot /ʃɒt/ n. 一针（药物）（flu shot指一针流感疫苗）
While the flu shot is the best defense currently available against seasonal influenza, it is not 100 percent effective. The CDC reports that the influenza vaccine typically reduces the risk of illness by between 40 and 60 percent, and that's only if the viruses included in the vaccine match the subtypes of influenza circulating that season.
currently /ˈkʌr(ə)ntli/ adv. 现在、目前（由current加后缀-ly变成副词）
seasonal /ˈsiːz(ə)n(ə)l/ adj. 季节性的（由season加后缀-al变成形容词）
influenza /ˌɪnfluˈenzə/ = flu 流感
effective /ɪˈfektɪv/ adj. 有效的（由effect加后缀-ive变成形容词）
vaccine /ˈvæksiːn/ n. 疫苗
risk /rɪsk/ n. 风险
subtype /ˈsʌbtaɪp/ n. 亚型
circulate /ˈsɜːkjuleɪt/ v. 流传、传播
As an RNA virus, influenza has a high tendency to mutate（变异）. Even within subtypes of influenza, the virus's genetic code is constantly mutating, causing season-to-season changes that scientists call antigenic（抗原的） drift.
RNA 是一种遗传物质
tendency /ˈtendənsi/ n. 倾向、趋向
genetic /dʒəˈnetɪk/ adj. 基因的
code /kəʊd/ n. 编码
constantly /ˈkɒnst(ə)ntli/ adv. 持续不断地（由constant加后缀-ly变成副词）
drift /drɪft/ n. 漂移、逐渐变化
"Most of the time, the virus changes just enough from one season to another so that last year's flu isn't exactly the same as what this year's flu is," Fauci says. "In order to get optimal protection, you recommend vaccinating people every year."
optimal /ˈɒptɪməl/ adj. 最优的
protection /prəˈtekʃ(ə)n/ n. 保护、防护（由protect加后缀-ion变成名词）
vaccinate /ˈvæksɪneɪt/ v. 给…打疫苗（由vaccine加后缀-ate变成动词）
To keep up with antigenic drift, scientists are constantly tweaking（微调） the flu vaccine, which is designed to respond to a surface protein called hemagglutinin, targeting what Fauci calls the "head" of the protein. "When you make a good response, the good news is you get protected. The problem is, the head is that part of the protein that has a propensity（习性） to mutate a lot."
keep up with 跟上
respond /rɪˈspɒnd/ v. 做出回应
surface /ˈsɜːfɪs/ adj. 表面的（这里指病毒表面）
protein /ˈprəʊtiːn/ n. 蛋白质
target /ˈtɑːɡɪt/ v. 以…为靶子
response /rɪˈspɒns/ n. 回应
The other end of the protein – the "stem" – is much more resistant to mutations（变异）. A vaccine that targets the hemagglutinin stem has the potential to provide protection against all subtypes of influenza and work regardless of antigenic drift, offering an essentially universal defense against the flu. NIAID is currently working to develop a candidate for a universal flu vaccine in a Phase 1 clinical trial. Results on the safety and efficacy（功效） of the vaccine are due in early 2020.
stem /stem/ n. 茎、柄
resistant /rɪˈzɪst(ə)nt/ adj. 抵抗的、抗拒的（由resist加后缀-ant变成形容词）
potential /pəˈtenʃ(ə)l/ n. 潜力
regardless /rɪˈɡɑːdləs/ of 不管
essentially /ɪˈsenʃ(ə)li/ adv. 基本上、本质上（由essential加后缀-ly变成副词）
universal /ˌjuːnɪˈvɜːs(ə)l/ adj. 普遍适用的
candidate /ˈkændɪdət/ n. 候选者
phase /feɪz/ n. 阶段
clinical /ˈklɪnɪk(ə)l/ adj. 临床的（由clinic加后缀-al变成形容词）
trial /ˈtraɪəl/ n. 试验（由try加后缀-al变成名词）
safety /ˈseɪfti/ n. 安全
due /djuː/ adj. 预计发生的
Along with protecting against the seasonal influenza, a universal vaccine would also arm humanity with a weapon against the next pandemic（大流行的） strain of the flu. Flu pandemics（大流行） come along occasionally and unpredictably, usually when a subtype of influenza jumps from animals to humans. This phenomenon introduces a flu so novel to humans that our immune systems are caught entirely off guard.
along with 伴随、除了
arm /ɑːm/ v. 武装、提供装备
humanity /hjuːˈmænəti/ n. 人类
weapon /ˈwepən/ n. 武器
strain /streɪn/ n. 菌株、品种
come along 到来
occasionally /əˈkeɪʒ(ə)n(ə)li/ adv. 偶尔
unpredictably /ˌʌnprɪˈdɪktəbli/ adv. 不可预测地
phenomenon /fəˈnɒmɪnən/ n. 现象
introduce /ˌɪntrəˈdjuːs/ v. 引入
novel /ˈnɒv(ə)l/ adj. 新颖的、新奇的
immune /ɪˈmjuːn/ adj. 免疫的
catch someone off guard 使某人措手不及
entirely /ɪnˈtaɪəli/ adv. 完全地（由entire加后缀-ly变成副词）
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