美国疾控中心宣布疫情已进入新阶段，赴美无需提供阴性证明
美国疾病预防控制中心（U.S. Centers for Disease Control）宣布，赴美旅客无需出具新冠检测阴性证明或者康复证明。
美国疾控中心在上周五的新闻发布会上宣布，从周日开始取消相关要求。美国从去年1月开始要求赴美旅客提供阴性证明或康复证明。外国旅客依旧需要出具新冠疫苗接种证明。
美国疾控中心官员在发布会上表示：“新冠疫情现在已经进入了新阶段”，包括“高度有效的”疫苗和美国人“高疫苗接种率和感染诱导的免疫力”等因素。
疾控中心官员称：“这些措施降低了美国的重症和死亡风险。”但疾控中心依旧建议赴美旅客在出发前三天内进行检测，一旦感染应取消行程。
疾控中心的数据显示，截至周日，美国有近78%的人口已经接种疫苗。此外，疾控中心根据商业实验室提供的抗体水平估计，近58%的美国人已经至少感染一次新冠。
然而众所周知，奥密克戎变异株具有免疫逃脱能力，尤其是两种相对较新的亚变种BA.4和BA.5被认为是到目前为止传播力最强的变异株，并且有资料证明它们能够逃脱疫苗和之前感染产生的免疫力。
据疾控中心统计，美国BA.4和BA.5感染者的比例不断提高，到两周前分别占感染者的5%和8%。
这两种变异株是否会像今年春天早些时候在南非时一样，成为美国的主要病毒株，现在仍是个未知数，但它们已经证明有与目前的主要病毒株B.2.12.1竞争的能力。两周前，B.2.12.1感染者的比例为62%，BA.1感染者占25%。
此外，虽然疫苗能够降低重症和死亡风险，但它无法阻止或至少无法完全阻止新冠病毒的传播。世界卫生组织（World Health Organization）称，突破性感染依旧会发生，而且“目前仍在进行相关研究，以了解接种疫苗能在多大程度上防止感染和传播病毒。”
世卫组织建议，为保护他人，已完成疫苗接种的人员应该继续采取预防措施，如配戴口罩和保持社交距离等。（财富中文网）
译者：刘进龙
审校：汪皓
美国疾病预防控制中心（U.S. Centers for Disease Control）宣布，赴美旅客无需出具新冠检测阴性证明或者康复证明。
美国疾控中心在上周五的新闻发布会上宣布，从周日开始取消相关要求。美国从去年1月开始要求赴美旅客提供阴性证明或康复证明。外国旅客依旧需要出具新冠疫苗接种证明。
美国疾控中心官员在发布会上表示：“新冠疫情现在已经进入了新阶段”，包括“高度有效的”疫苗和美国人“高疫苗接种率和感染诱导的免疫力”等因素。
疾控中心官员称：“这些措施降低了美国的重症和死亡风险。”但疾控中心依旧建议赴美旅客在出发前三天内进行检测，一旦感染应取消行程。
疾控中心的数据显示，截至周日，美国有近78%的人口已经接种疫苗。此外，疾控中心根据商业实验室提供的抗体水平估计，近58%的美国人已经至少感染一次新冠。
然而众所周知，奥密克戎变异株具有免疫逃脱能力，尤其是两种相对较新的亚变种BA.4和BA.5被认为是到目前为止传播力最强的变异株，并且有资料证明它们能够逃脱疫苗和之前感染产生的免疫力。
据疾控中心统计，美国BA.4和BA.5感染者的比例不断提高，到两周前分别占感染者的5%和8%。
这两种变异株是否会像今年春天早些时候在南非时一样，成为美国的主要病毒株，现在仍是个未知数，但它们已经证明有与目前的主要病毒株B.2.12.1竞争的能力。两周前，B.2.12.1感染者的比例为62%，BA.1感染者占25%。
此外，虽然疫苗能够降低重症和死亡风险，但它无法阻止或至少无法完全阻止新冠病毒的传播。世界卫生组织（World Health Organization）称，突破性感染依旧会发生，而且“目前仍在进行相关研究，以了解接种疫苗能在多大程度上防止感染和传播病毒。”
世卫组织建议，为保护他人，已完成疫苗接种的人员应该继续采取预防措施，如配戴口罩和保持社交距离等。（财富中文网）
译者：刘进龙
审校：汪皓
Travelers to the U.S. no longer have to show proof of a negative COVID-19 test or documentation of recovery from the virus, according to the U.S. Centers for Disease Control.
The order was lifted Sunday, according to a Friday news release from the federal health agency. It had been in place since January of last year. Foreign travelers must still show proof of COVID-19 vaccination.
“The COVID-19 pandemic has now shifted to a new phase,” officials said in the release, citing “highly effective” vaccines and “high rates of vaccine- and infection-induced immunity” among Americans, among other factors.
“Each of these measures has contributed to lower risk of severe disease and death across the United States,” officials said, adding that the agency still recommends travelers coming to the U.S. get tested within three days of departure and do not travel if they are sick.
Nearly 78% of the U.S. population had been vaccinated as of Sunday, according to CDC data. Additionally, the CDC estimates, based on antibody levels from commercial labs, that nearly 58% of Americans have been infected at least once.
Omicron variants, however, are known for their ability to evade immunity–especially BA.4 and BA.5, two relatively new subvariants thought to be the most transmissible so far, with documented ability to evade immunity both from vaccination and prior infections.
Levels of BA.4 and BA.5 are ticking up in the U.S., comprising 5% and 8% of infections as of two weeks ago, according to the CDC. New data will be released Tuesday.
While it’s unknown if the variants will dominate the U.S. as they did earlier this spring in South Africa, they’re already proving themselves as competitors against the currently dominant B.2.12.1, which comprised 62% of infections two weeks ago, and BA.1, which comprised 25%.
Additionally, while vaccines are known to reduce the risk of severe illness and death, they don’t prevent the spread of COVID–at least not fully. Breakthrough infections still occur, and “research is ongoing to understand the extent to which being vaccinated stops you from becoming infected and passing the virus on to others,” according to the World Health Organization.
Those who are fully vaccinated should continue to practice prevention measures like masking and social distancing to protect others, it adds.
