乔·拜登总统的新基准在与...的斗争中新冠肺炎(新型冠状病毒肺炎)确保70%的美国成年人在7月4日之前至少注射一针，这似乎是对科学家们几个月来一直在说的话的默认:根除导致新冠肺炎的病毒可能是不可能的。但是如果足够多的美国人得到一些保护，这将变得容易控制。
这种方法被科学家和政治家视为比等待“群体免疫”更为务实的处理新冠肺炎问题的方法尤其是考虑到四分之一的美国人可能永远不会接受疫苗。
新罕布什尔州州长克里斯·苏努努在周二的电话采访中说:“我们可能会在未来几年内出现病例数的高峰和低谷，但这些病例将出现在选择不接种疫苗的人群中。”。
自大流行开始以来，美国人就接受了病毒终有一天会消失的想法，要么是因为有足够多的人成为感染了病毒或者接种疫苗。这种集体或“群体”免疫将阻止病毒传播给新的人，消除威胁。
这个想法太有吸引力了，以至于唐纳德·特朗普总统的一些高级顾问呼吁允许年轻人感染病毒，这样病毒就会更快消失，企业就可以不受限制地重新开业。特朗普去年秋天混淆了他对“从众心理”这个术语的引用，他预测“有了疫苗，我认为它会很快消失。”
到1月份，也就是就职后的第五天，拜登说他“相信到夏天，我们将会朝着群体免疫的方向前进。”到3月份，拜登说群体免疫是放弃面具的先决条件。
拜登今年春天举着口罩说:“我们必须达到群体免疫的水平，也就是说，我们有绝大多数美国人接种过疫苗，然后我们才能停止戴这些东西。”。
然而，自那以后，美国疫苗的推出相当慢只有32%的人口完全免疫。联邦政府运营的大型疫苗接种站正在关闭，转而使用更小的移动货车来帮助农村和其他难以到达的社区的人们。
预计本周一些州将首次减少可用疫苗剂量。政府官员周二在每周一次的电话中告诉州长，由于一些州预计会留下供应量，其他州现在可以要求增加剂量，如果他们想要的话。
疫苗接种如此早期的突然放缓健康官员警告说根除病毒可能是不可能的。另一个担忧是，潜在的危险全球变异可能在海外形成，威胁到疫苗。卫生官员已经预测未来几年可能需要加强注射。
疾病控制和预防中心前主任汤姆·弗里登博士说:“根除从来就不在计划之中……COVID与我们同在，前途未卜。”
“这并不意味着大流行与我们同在。我们可以结束这场流行病，”他说，并指出美国可以以目前每天5万例感染的水平无法应对的方式管理较小的孤立疫情。
拜登在周二的讲话中似乎也承认了这一点。
“嗯，我想100%接种，”他谈到疫苗接种率时说。“但我认为，现实地说，从现在到7月4日，我们可以达到70%。”
科学家说，群体免疫的概念一直很微妙，很难确定。虽然通常被认为意味着彻底根除病毒，但群体免疫也可以围绕更容易管理的目标来定义，例如显著减缓传播。
美国顶尖传染病专家安东尼·福奇博士最初估计，大约70-85%的人口必须对病毒产生免疫力，病毒才会消失，但他后来放弃了这个数字。
周二，在美国州长和白宫之间的一个私人电话中，福奇试图让州官员远离任何估计，因为他说没有人知道这个神奇的数字会是什么。
“有一件事……我们绝对肯定地知道，随着越来越多的人接种疫苗，病例数量将会越来越少。所以我们的目标是尽可能让更多的人接种疫苗，不要被这个难以捉摸的数字概念所困扰，没有人真正知道这个数字是多少，”福奇告诉州长们。
根据一名高级政府官员的说法，拜登的新基准与其说是取消任何从众豁免的概念，不如说是在总统上任的第一个100天已经过去的情况下，为国家设定“一个集体目标”。
但拜登70%的成年人接种疫苗的数字似乎也是对卫生专家和州官员在实地目睹的COVID病例“临界点”的认可。在足够多的人接种疫苗后，住院率和死亡率急剧下降。
例如，在新罕布什尔州，超过60%的成年人已经接种了第一剂疫苗，这使得它成为少数几个接种率最高的州之一，并慢慢接近拜登的70%的目标。
共和党人苏努努说，他认为这是成功的。
当被问及在这场大流行中会取得什么样的成功时，苏努努说，“我们在那里”。“我不想粉饰太平，但是……我们的经济正在蓬勃发展。每个想要一种疫苗的人都有。”
阿拉巴马大学伯明翰分校的医学教授、阿拉巴马疫苗研究中心主任保罗·戈珀特博士说，他认为“成功的最终定义”是住院和死亡人数与季节性流感相似或更低。每年流感死亡人数估计高达6万人。
费城儿童医院疫苗教育主任兼传染病医生保罗·奥菲特博士说，一个基准可能是该国明年秋天的情况。他说，如果到明年11月到明年1月，每天死于COVID的人数少于50人，这可以被认为是一项成功。
“如果我们有足够的人口免疫水平，那么我们在冬天只会有一个小的颠簸(在某些情况下)。奥菲特说:“另一方面，如果我们不这样做，那么明年冬天我们将再次看到需求激增。”。
弗里登说，在海外开发的新的、潜在更危险的病毒变种仍然是通配符。引入这样一种变体可能会改变任何一个拥有大量未接种疫苗人群的州的方程式。这就是为什么让尽可能多的人接种疫苗仍然是目标。
“我理解人们想要清晰，”弗里登说。“但现实是，有很多我们不知道的东西。如果人们非常肯定地告诉你他们知道，他们就不知道自己在说什么。”
'Herd immunity' gives way to 'good enough' as Biden sets new benchmark for vaccines
President Joe Biden'snew benchmarkin the fight againstCOVID-19-- ensuring 70% of American adults to get at least one shot by July 4 -- seems to be a tacit acknowledgement of what scientists have been saying now for months: Eradicating the virus that causes COVID-19 might not be possible. But if enough Americans get some protection, it'll become manageable.
That approach is being embraced by scientists and politicians alike as a considerably more pragmatic approach to dealing with COVID-19 than the idea of waiting on "herd immunity,"especially considering thata fourth of Americansmight never acceptthe vaccine.
"We're going to have highs and lows of case numbers potentially for years, but those are going to be in the population that chooses not to vaccinate," said New Hampshire Gov. Chris Sununu in a phone interview Tuesday.
Since the pandemic began, Americans have embraced the idea that the virus would one day evaporate, either because enough people becameinfected with the virusorreceived a vaccine. That collective, or "herd," immunity would block the virus from transmitting to new people, eradicating the threat.
The idea was so alluring that some top advisers to President Donald Trump called for allowing younger people to get sick with the virus so it would go away sooner and businesses could reopen without restrictions. Trump, who last fall jumbled his reference to the term as "herd mentality," predicted that "with a vaccine, I think it will go away very quickly."
By January, five days after taking office, Biden said he was "confident that by summer we're going to be well on our way to heading toward herd immunity." And by March, Biden said herd immunity was a prerequisite to giving up masks.
"We've got to reach the point where we have herd immunity -- meaning where we have a vast majority of the American people have been vaccinated -- before we can stop wearing these," Biden said this spring, holding up his mask.
Since then, however, the U.S. vaccine rollout hasslowed considerablywith only 32% of the population fully immunized. Big federally run vaccination sites are closing up shop in favor of smaller mobile vans that reach people in rural and other hard-to-reach neighborhoods.
And for the first time, some states this week were expected to decline portions of the vaccine doses available. Administration officials told governors in a weekly phone call Tuesday that because some states were expected to leave behind supply, other states can now ask for added doses if they want it.
The sudden slowdown so early in the rollout of vaccinations hashealthofficials warning that eradication of the virus might not be possible. Another concern is that potentially dangerous global variants could form overseas that threaten the efficacy of thevaccines. Health officials have already predicted that booster shots will probably be needed for years.
"Eradication was never in the cards … COVID is with us for the indefinite future," said Dr. Tom Frieden, the former director of Centers for Disease Control and Prevention.
"That doesn't mean that the pandemic is with us. We can end the pandemic," he said, noting the U.S. could manage smaller isolated outbreaks in ways it can't with the current level of 50,000 some infections a day.
Biden seemed to acknowledge as much in his remarks Tuesday.
"Well, I'd like to get it 100%," he said of the vaccination rate. "But I think, realistically, we can get to (70%) between now and July 4th."
Scientists said the concept of herd immunity has always been nuanced and a difficult threshold to pinpoint. Although often taken to mean total eradication of the virus, herd immunity can also be defined around more manageable goals, such as dramatically slowing down transmission.
Dr. Anthony Fauci, the nation's top infectious disease expert, had initially estimated that roughly 70-85% of a population must become immune to the virus for it to go away, but he's since backed away from the number.
In a private phone call Tuesday between the nation's governors and the White House, Fauci tried to steer state officials away from any estimate because he said no one knows what the magic number would be.
"The one thing … that we absolutely know for sure is that as you get more and more people vaccinated, the number of cases are going to come down and down and down. So our goal is just get as many people as you can possibly get vaccinated, and don't get hung up on this elusive concept of a number that nobody really knows what that number is," Fauci told the governors.
According to a senior administration official, Biden's new benchmark was less about doing away with any notion of herd immunity and more about setting "a collective goal for the country" now that the president's first 100 days in office had passed.
But Biden's 70% figure of vaccinated adults also appears to be a nod to the "tipping point" in COVID cases that health experts and state officials have witnessed on the ground. That's the point at which hospitalizations and death rates plummet after enough people are vaccinated.
In New Hampshire, for example, more than 60% of adults already have the first dose, making it one of a few states with the highest vaccination rates and inching close to Biden's goal of 70%.
Sununu, a Republican, said he sees that as a success.
"We're there," Sununu said when asked what success might look like in the pandemic. "I don't mean to like sugarcoat it but … our economy is booming. And everyone who wants one of the vaccines has it."
Dr. Paul Goepfert, professor of medicine at the University of Alabama at Birmingham and Director of the Alabama Vaccine Research Center, said he thinks the "ultimate definition of success" would be hospitalizations and deaths similar to that of the seasonal flu or lower. Annual flu deaths are estimated to go as high as 60,000 in a year.
Dr. Paul Offit, the director of vaccine education and physician of infectious diseases at Children's Hospital of Philadelphia, said one benchmark could be how the country fares next fall. If fewer than 50 people die every day of COVID by next November through January -- a period of time you'd expect to see deaths peak -- that could be considered a success, he said.
"If we have an adequate level of population immunity, then we will only have a small bump (in cases) over the winter. If on the other hand we don't, then we will again see a surge next winter," Offit said.
Frieden said new, potentially more dangerous variants of the virus developing overseas remain the wildcard. Introduction of such a variant could change that equation for any state with large pockets of unvaccinated people. That's why getting as many people vaccinated as possible has to remain the goal.
"I understand that people want clarity," Frieden said. "But the reality is that there's a lot we don't know. And if people tell you with great certainty that they know, they don't know what they are talking about."
