题型:阅读理解 题类: 难易度:困难
河南省周口市九师联盟四月联考2023-2024学年高三下学期4月期中英语试题(音频暂未更新)
The Ebola virus is an infectious disease that for years had almost no treatments, and it kill s about half the people it infects. Now a new study published in The Lancet Infectious Diseases shows that a promising vaccine (疫苗), named rVSV△G-ZEBOV-GP, doesn't just help to reduce infections, it also can cut those death numbers in half.
The vaccine is a single-dose (单剂) muscular one that causes cells to produce one of the virus's proteins. "Later, if the person is exposed to Ebola,"explains Rebecca Coulborn, a scientist with Epicentre, the medical research arm of Doctors Without Borders, "their immune system will recognize the viral protein. This recognition allows the immune system to be prepared to attack the virus and protect the person from Ebola virus disease."
Researchers showed rVSV△G-ZEBOV-GP was effective at reducing the risk of infection, but no one knew how capable it was of preventing death in someone who was vaccinated after becoming infected during an epidemic (流行病). To figure it out, Coulborn and her colleagues focused their efforts on the second-largest Ebola outbreak ever recorded, which occurred in the Democratic Republic of Congo between 2018 and 2020.
"Every single Ebola health facility across the entire Ebola epidemic had a standardized list of all admissions," says Coulborn. This list included 2,279 confirmed Ebola patients, and it recorded whether or not each person had been vaccinated before they got sick—and if so, when they'd received the vaccine.
Coulborn found the death rate was 56% among the unvaccinated. But for those who'd received the vaccine, that rate was cut in half. This was true no matter when someone got vaccinated before the appearance of symptoms. Additionally, those who'd been vaccinated had less virus circulating in their bodies than those who hadn't. So the vaccine played an important role.
Rebecca Coulborn says she feels buoyed by the results—since they offer clear evidence that people who're at risk of contracting Ebola should be vaccinated early. It's an opportunity to cut chains of transmission (传播) and prevent an outbreak before it gains speed.
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