The CDC also advised all K-12 students, teachers, workers, and visitors to wear a face-covering, or mask. The recommendation is in effect for both unvaccinated and vaccinated people.
美国疾控预防中心还建议所有中小学生、教师、工作人员和访客戴上口罩。该建议对未接种和已接种疫苗的人群均有效。
The health agency said the highly infectious Delta variant has led to a large increase of coronavirus cases in parts of the country. The variant now represents more than 80 percent of new cases, especially in areas where fewer people are vaccinated. The CDC's investigation also showed that, in rare cases, some vaccinated people infected with the Delta variant may "spread the virus to others."
这家卫生机构表示，高传染性的德尔塔变种导致美国部分地区的新冠病毒病例大幅增长。该变种现在占到了新增病例的80%以上，尤其是在疫苗接种量较低的地区。美国疾控预防中心的调查还显示，在极少数情况下，一些接种了疫苗的人士在感染德尔塔变种后可能会将病毒传播给他人。
CDC Director Rochelle Walensky added, "This new science is worrisome and, unfortunately, warrants an update to our recommendation."
美国疾控预防中心主任罗谢尔·瓦伦斯基还表示：“这一新的科学发现令人担忧，不幸的是，有必要更新我们的建议。”
The recommendation marked a sharp change of the CDC's position from two months ago. On May 13, the health agency said fully vaccinated Americans did not need to wear masks or social distance in most places.
该建议标志着美国疾控预防中心的立场与两个月前相比发生了急剧变化。该卫生机构在5月13日表示，已接种疫苗的美国人在大多数地方都不需要戴口罩或是保持社交距离。
At that time, the CDC said people should only wear face coverings in some settings like buses, airplanes and hospitals. And it said people with weak immune systems, such as those undergoing cancer treatment, should talk with their doctors before giving up their masks.
当时，美国疾控预防中心表示，人们只用在公共汽车、飞机和医院等环境中戴口罩。它还说免疫系统较弱的人群，例如接受癌症治疗的人士应该在放弃口罩之前与他们的医生沟通。
Delta variant
德尔塔变种
The Delta variant was first identified in India last March. By July, the World Health Organization said it had spread to 96 countries.
德尔塔变种于3月在印度首次被发现。世界卫生组织表示，到了7月，它已经传播到96个国家。
In the U.S., the CDC reported that more than 63 percent of U.S. counties are now considered to be areas "with substantial and high transmission" of COVID-19. Most of them are in the South.
美国疾控预防中心报告称，美国63%以上的县现在被认为是新冠肺炎大量和高度传播的地区。它们大多数都在南方。
On Tuesday, Walensky said, "Vaccinated individuals continue to represent a very small amount of transmission occurring around the country." She recommended that unvaccinated people get shots and asked everyone to wear masks "to help prevent the spread of the Delta variant and protect others -- this includes schools."
瓦伦斯基周二表示：“接种过疫苗的个人在全国各地的病毒传播中仍然只占极少数。”她建议未接种者接种疫苗，并要求每个人戴上口罩，“以帮助防止德尔塔变种的传播并保护他人，包括学校。”
Speaking to reporters, U.S. President Joe Biden said, "The more we learn about this virus and the Delta variation, the more we have to be worried and concerned. And there's only one thing we know for sure — if those other 100 million people got vaccinated, we'd be in a very different world."
美国总统拜登对记者表示：“我们对新冠状病毒和德尔塔变种病毒的了解越多，我们就越需要担心。只有一件事我们可以肯定，那就是如果另外1亿人也接种了疫苗，我们的世界将会大不相同。”
The Biden administration also announced that it is asking all workers and visitors to wear masks at the White House. That is because the latest CDC information shows that Washington, DC faces a substantial level of coronavirus transmission.
拜登政府还宣布要求所有工作人员和访客在白宫戴上口罩。这是因为美国疾控预防中心的最新信息显示，华盛顿特区面临着相当程度的新冠病毒传播。
American Federation of Teachers President Randi Weingarten praised the agency's new guideline to wear masks in schools. She said in a statement, "It is a necessary precaution until children under 12 can receive a COVID-19 vaccination and more Americans 12 and older get vaccinated."
美国教师联合会主席兰迪·温加藤称赞了该机构要求在学校佩戴口罩的新指南。她在一份声明中表示：“在12岁以下儿童可以接种新冠肺炎疫苗并且更多12岁及以上人群接种疫苗之前，这是一项必要的预防措施。”
The new CDC guidelines, however, are only recommendations. It is up to states and local officials to follow them. And many Americans, especially in southern states, may choose not to follow them.
然而，美国疾控预防中心的这份新指南只是建议。它取决于各州和地方官员的跟进。许多美国人，尤其是南方各州，可能会选择不跟进。
Dr. Isaac Weisfuse is a professor at Cornell University Public Health. He told the Reuters news agency that some people might resist. "I think we will get blowback because I think people might view it as backtracking," he said.
艾萨克·魏斯福斯博士是康奈尔大学公共卫生学院的教授。他对路透社表示，有些人可能会抵制。他说：“我认为我们会遭到反击，因为我认为人们可能会将其视作倒退。”