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The risk posed by the slow pace of the vaccination campaign is now amplified by new variants of SARS-CoV-2 that appear to spread more easily among people, which means a COVID-19 vaccine has never been more critical. First reported in the U.K. in December, the mutation in SARS-CoV-2 has since appeared in the U.S., while yet another, more worrisome variant of the virus—which may be better able to evade the immune defenses the body generates—has emerged in South Africa. With these new mutated versions of the virus, the pace and completeness of vaccinating the public becomes more crucial. The point of mass vaccination is to achieve herd immunity, in which the majority of the population is protected against COVID-19. For the virus, such a scenario is similar to a thief encountering a neighborhood of secured and alarmed homes: it's harder to break in. The more quickly a fortress of immunity is built, the easier it is to thwart the virus as it hits blockade after blockade. If the vaccination effort is more piecemeal—as it is in the U.S. now with the plodding rollout—there may be more opportunities for SARS-CoV-2 to develop mutations that make it resistant to the vaccines. If that happens, those mutant variants can outcompete their cousins and dominate.
疫苗接种的缓慢步伐所带来的风险现在因SARS-CoV-2的新变种而放大，这些变种似乎更容易在人群中传播，这意味着新冠疫苗从未像现在这样至关重要。英国于去年12月首次报道了SARS-CoV-2的变异，之后这种变异出现在美国，而另一种更令人担忧的病毒变异——它可能能更好地躲避人体产生的免疫防御——出现在南非。这些新的变异版病毒的出现使得公众接种疫苗的速度和完整性变得更加关键。大规模接种疫苗的目的是实现群体免疫，使大多数人免受新冠感染。对于病毒来说，这种情况类似于小偷遇到了一个安全且装有警报的家庭：更难闯入。免疫堡垒建立得越快，就越容易阻止病毒袭击一个又一个封锁。如果疫苗接种工作更加零碎——就像美国现在缓慢推出的疫苗一样——SARS-CoV-2可能会有更多的机会发生突变，从而对疫苗产生耐药性。如果发生了这种情况，这些变异的变种就会超过它们的表亲，占据主导地位。
Some experts argue that even partial vaccine protection among a larger number of people is better than complete protection in a smaller group. They advocate for people getting their second shot about three months after the first (instead of the 21 or 28 days currently recommended). That way, more people could get vaccinated at least once and enjoy partial protection of slightly over 50% on average against COVID-19, according to some estimates, compared with the 95% provided by the current plan—and the virus's spread would be slowed as well. It's not perfect, but it could do more good for more people.
一些专家认为，在大量人群中接种部分疫苗比在一小部分人群中接种完整疫苗要好。他们提倡人们在第一次注射3个月后再注射第二次(而不是目前建议的21或28天)。这样，更多的人就可以接种至少一次疫苗。根据一些估计，与目前计划提供的95%相比，他们可以享受到针对新冠的平均略高于50%的部分保护，而且病毒的传播速度也将放缓。它并不完美，但可以为更多的人做更多的好事。
The U.K. adopted this strategy on Dec. 30—a controversial and, some health experts say, premature decision. There is no strong evidence for deferring the second dose, which the U.S. Food and Drug Administration (FDA) reiterated in a Jan. 4 statement supporting the existing dosing regimen. It's also unclear whether the new SARS-CoV-2 variants cause worse disease and warrant such a change. So far, the antibodies and immune response generated by the vaccines can still neutralize the mutant viruses. Given how far the U.S. vaccination program has fallen short already, delaying the second dose, says Dr. Leana Wen, former health commissioner for Baltimore City, is "solving for the wrong problem. If we are unable to even administer the supplies of vaccine we have at the moment, what is the purpose of trying to increase the supply when we should be focused on increasing the rate of administration of the vaccine?" Frieden agrees: "We should be focusing on getting the vaccine out as rapidly, as widely and as equitably as possible."
英国于12月30日采取了这一策略——一些健康专家认为，这是一个有争议的、而且为时过早的决定。美国食品和药物管理局在1月4日的一份声明中重申，没有强有力的证据可以推迟第二次给药，支持现有的给药方案。目前还不清楚新的SARS-CoV-2变种是否会导致更严重的疾病，是否需要这样的变化。到目前为止，疫苗产生的抗体和免疫反应仍然可以中和突变病毒。巴尔的摩前卫生专员利阿纳·温博士说，考虑到美国疫苗接种计划已经远远不够，推迟第二剂疫苗接种是“解决错误的问题”。如果我们连目前的疫苗供应都无法满足，那么当我们把重点放在提高疫苗接种率上时，试图增加疫苗供应的目的是什么呢？”弗里登表示同意：“我们应该专注于尽可能迅速、尽可能广泛和尽可能公平地生产疫苗。”
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