Delta
德尔塔变种
The Delta variant, first identified in India in December 2020, remains the most troubling kind of SARS-CoV-2 virus.
德尔塔变种于2020年12月在印度被首次发现，它仍然是最令人不安的新冠病毒版本。
The World Health Organization describes Delta as a variant of concern. That means the variant can increase disease spread, cause more severe disease or reduce the effects of vaccines and treatments.
世卫组织称德尔塔变种为值得关切的变异株。这意味着该变种会增加疾病传播，导致更严重疾病或降低疫苗和治疗的效果。
Shane Crotty is a virus expert at the La Jolla Institute for Immunology in San Diego. He described Delta's ability to spread as a "superpower."
尚恩·克罗蒂是圣地亚哥拉霍亚免疫学研究所的病毒专家。他称德尔塔的传播能力超级强劲。
Delta is able to spread more than two times faster than other SARS-CoV-2 variants, says the U.S. Centers for Disease Control and Prevention. Studies suggest it may be more likely to put infected people in the hospital than earlier forms of the virus.
美国疾控预防中心表示，德尔塔的传播速度比其它新冠病毒变种要快两倍多。研究表明，与早期病毒版本相比，德尔塔致使感染者住院的可能性更大。
Delta also can cause symptoms two to three days sooner than the original SARS-CoV-2, giving the immune system less time to put up a defense.
德尔塔还比最初的新冠病毒早两到三天引发症状，从而使免疫系统的防御时间更短。
People infected with Delta carry around 1,200 times more virus in their noses compared with the first kind of the coronavirus. The amount of virus in vaccinated individuals who become infected with Delta is about the same as those who are unvaccinated. And both vaccinated and unvaccinated people can spread the virus to others.
与最初版本的新冠病毒相比，德尔塔变种感染者鼻腔内的病毒携带量大约是1200倍。完成疫苗接种的德尔塔变种感染者携带的病毒量与未接种疫苗者大致相同。疫苗接种完成者与未接种者都能将病毒传播给他人。
In vaccinated people, however, the amount of virus drops more quickly, so they likely spread the virus for a shorter time.
然而，在完成疫苗接种的人士当中，病毒量下降得更快，因此他们传播病毒的时间可能更短。
The WHO says Delta makes up 99.5 percent of all genetic samples of coronavirus infection reported to public databases.
世卫组织表示，德尔塔变种占到了向公共数据库报送的所有新冠病毒感染基因样本的99.5%。
However, in South America, where Delta has spread more slowly, other variants such as Gamma, Lambda and Mu still make up a large number of reported cases.
然而，在德尔塔变种传播更慢的南美洲，伽马、拉姆达和缪等变种仍然占据了大量的报告病例。
Many vaccine experts predict that all future variants will develop from Delta. One such variant is known as AY.4.2. In Britain, the variant represents 10 percent of virus samples.
许多疫苗专家预测，未来所有变种都将自德尔塔发展而来。一种此类变种被称为AY.4.2.变种。在英国，该变种占到了病毒样本的10%。
The British government's health security agency has named the AY.4.2 a "Variant Under Investigation." Officials say an early study suggests the variant does not substantially reduce vaccine effectiveness in comparison to Delta. However, there is some evidence that AY.4.2 could spread more easily than the older Delta, the agency said.
英国政府的健康安全机构将AY.4.2变种定义为一种“调查中的变种。”有关官员表示，一项早期研究表明，与德尔塔变种相比，该变种并未显著降低疫苗有效性。然而该机构表示，有一些证据表明， AY.4.2 变种比更老的德尔塔变种更容易传播。
AY.4.2 has spread to at least 42 countries, including the United States.
AY.4.2变种已经传播到了至少42个国家，其中就包括美国。
More on the way?
还会有更多变种来袭？
Virus experts are closely watching the evolution of Delta.
病毒专家正在密切关注德尔塔变种的演变。
While current vaccines prevent severe disease and death, they do not block infection. A person can be fully vaccinated and still carry and pass the virus.
虽然目前的疫苗可以预防重症和死亡，但它们并不能防止感染。完全接种者仍然会携带和传播病毒。
What is needed to defeat SARS-CoV-2 is likely a new kind of vaccine that also blocks virus spread, said Dr. Gregory Poland, a vaccine developer at the Mayo Clinic. Until then, Poland and other experts say, the world remains easily hurt by the virus.
梅奥诊所的疫苗开发人员格雷戈里·博兰德博士表示，打败新冠病毒可能需要一种也能阻断病毒传播的新型疫苗。博兰德和其它专家表示，在那之前，全球仍然很容易受到病毒的伤害。