A SARS-CoV-2 virus particle isolated from a patient. (National Institute of Allergy and Infectious Diseases)
从病人身上分离出的SARS-CoV-2病毒颗粒。(国家过敏和传染病研究所)
One of the enduring questions of the COVID-19 pandemic is how much immunity people are left with after recovering from a coronavirus infection. New research suggests the level of protection is comparable to getting a vaccine — at least for a few months.
COVID-19大流行的一个持久问题是，人们从冠状病毒感染中恢复后还能保留多少免疫力。新的研究表明，至少在几个月内，疫苗的保护水平相当于接种疫苗。
Among a group of hundreds of thousands of Americans who tested positive for a SARS-CoV-2 infection, the risk of developing a subsequent infection more than three months later was about 90% lower than for people who had not been previously infected and therefore had no immunity to the virus, according to researchers from the National Cancer Institute.
在一群成千上万的美国人阳性SARS-CoV-2感染,感染发展后续的风险超过三个月后是低于90%的人没有被感染,因此没有对病毒的免疫力,根据美国国家癌症研究所的研究人员。
For the sake of comparison, when the vaccines made by Pfizer-BioNTech and Moderna were tested in Phase 3 clinical trials, they reduced the risk of developing COVID-19 by at least 94%.
为了便于比较，当辉瑞生物技术公司(Pfizer-BioNTech)和Moderna公司生产的疫苗进行3期临床试验时，它们发生COVID-19的风险至少降低了94%。
The findings, published Wednesday in JAMA Internal Medicine, could help inform plans for returning workers to their offices, sending students and teachers back to school campuses and allowing more of the economy to reopen.
周三发表在《美国医学会内科杂志》(JAMA Internal Medicine)上的研究结果，可能有助于为员工重返办公室、让学生和教师重返校园、让更多经济领域重新开放的计划提供信息。
"I think we knew this, that immunity [after natural infection] lasts a long time," said Dr. Monica Gandhi, an infectious-disease specialist at UC San Francisco who was not involved in the new research. "But it's still very exciting."
“我想我们知道，[自然感染后]免疫力会持续很长一段时间，”莫妮卡·甘地博士说，她是加州大学旧金山分校的传染病专家，没有参与这项新研究。“但这仍然很令人兴奋。”
There are three important things scientists need to know to understand the biological value of coronavirus antibodies, said Dr. Mitchell H. Katz, who leads NYC Health and Hospitals. They are: Do antibodies protect against infection? Can they be reliably detected with current tests? And, if they do offer some protection, how long does it last?
纽约卫生和医院负责人米切尔·h·卡茨(Mitchell H. Katz)博士说，科学家需要了解三件重要的事情，才能了解冠状病毒抗体的生物学价值。它们是:抗体能防止感染吗?目前的测试能可靠地检测到它们吗?而且，如果它们确实提供了一些保护，它能持续多久?
The new study “provides reassuring answers to the first and second questions,” Katz wrote in an editor’s note that accompanied the study.
这项新研究“为第一个和第二个问题提供了可靠的答案，”卡茨在研究附带的编者按中写道。
To investigate coronavirus immunity, the cancer researchers examined the results of more than 3 million blood tests administered to Americans between the start of the pandemic and Aug. 23. A total of 378,606 of those tests were positive for SARS-CoV-2 antibodies — a sign that the person who provided the sample had an active coronavirus infection.
为了调查冠状病毒的免疫力，癌症研究人员检查了从大流行开始到8月23日期间对美国人进行的300多万次血液测试的结果。其中378,606项检测结果为SARS-CoV-2抗体阳性，这表明提供样本的人感染了活跃的冠状病毒。
Among the millions of people who were tested, some — about 11% of those who tested positive and 9.5% of those who tested negative — later took a different test to look for evidence of the coronavirus' genetic material in patient samples, which are typically gathered via the nose, throat or from saliva.
在数以百万计的人测试,一些——大约11%的那些阳性和9.5%的测试- -后来采取了不同的测试来寻找证据冠状病毒的遗传物质在患者样本,通常聚集通过鼻子,喉咙或唾液。
The researchers used these results to see whether people who'd had a coronavirus infection were any less likely than their uninfected counterparts to have SARS-CoV-2 particles in their system. For their analysis, they sorted the results into four groups based on the gap between the antibody test and the genetic test.
研究人员利用这些结果来观察感染了冠状病毒的人是否比未感染的人体内存在SARS-CoV-2颗粒的可能性更小。为了进行分析，他们根据抗体测试和基因测试之间的差距将结果分为四组。
After running the numbers, the researchers found that between 3% and 4% of those who originally tested negative for coronavirus antibodies later tested positive with the genetic test. This was true across all four time intervals: 0 to 30 days, 31 to 60 days, 61 to 90 days and more than 90 days. The consistency was probably a reflection of the relatively stable rate at which people in their communities were being infected at the time, the researchers said.
在计算了这些数字后，研究人员发现，最初冠状病毒抗体检测呈阴性的人中，有3%至4%后来在基因检测中呈阳性。这在所有四个时间间隔都是正确的:0到30天，31到60天，61到90天和超过90天。研究人员说，这种一致性可能反映了他们所在社区的人在当时被感染的比率相对稳定。
Contrast that to the people who originally tested positive for coronavirus antibodies. Their genetic test results were positive at very high rates in the first 30 days (11.3%), which the researchers said was probably a sign that leftover viral particles were still being flushed from their systems.
这与最初冠状病毒抗体检测呈阳性的人形成了对比。他们的基因检测结果在头30天里呈阳性(11.3%)，研究人员说这可能是残留的病毒颗粒仍在从他们的系统中被冲走的迹象。
However, the positivity rate for the genetic test plunged to 2.7% in the second month after infection, then fell to 1.1% in the third month. And after those 90 days, only 0.3% of people with a past coronavirus infection had another infection that was detected with a genetic test.
然而，在感染后的第二个月，基因检测的阳性率下降到2.7%，然后在第三个月下降到1.1%。在这90天之后，只有0.3%曾经感染过冠状病毒的人在基因检测中发现了另一种感染。
That coronavirus infection rate was 10 times lower than for the people who presumably had not been previously infected.
该冠状病毒感染率比那些可能从未感染过的人低10倍。
That level of protection appears to be comparable to the benefits offered by the Pfizer and Moderna vaccines in their clinical trials, the study authors pointed out.
该研究的作者指出，这种水平的保护似乎可以与辉瑞和Moderna疫苗在临床试验中提供的好处相媲美。
“Of course, protection induced by a safe vaccine is clearly preferable,” they were quick to add, “as the population-wide risk of a serious outcome from an authorized or approved vaccine is expected to be orders of magnitude lower than that from natural infection.”
“当然，由安全疫苗引起的保护显然是更好的，”他们很快补充说，“因为一种经过授权或批准的疫苗在整个人群中发生严重后果的风险预计要比自然感染的风险低几个数量级。”
Though the findings may be of great interest to scientists, it's unlikely they'll make much practical difference at this stage of the pandemic, Gandhi said. That's because vaccines appear to be at least as protective as a past infection, and they're already being rolled out.
甘地说，尽管科学家们可能对这些发现非常感兴趣，但在目前的大流行阶段，它们不太可能产生很大的实际影响。这是因为疫苗看起来至少和过去的感染一样有保护作用，而且它们已经在推广。
These findings "could have been used two months ago," she added.
她补充说，这些发现“两个月前就可以用了”。
While this study didn't gauge how long the benefits of a prior infection last beyond 90 days, other lines of evidence suggest it takes a while to wane. For instance, Gandhi pointed to a paper in Science that found that immune cells triggered by SARS-CoV-2 remained in the body for at least eight months.
虽然这项研究没有评估之前感染的益处能持续超过90天的时间，但其他证据表明，这种益处需要一段时间才能减弱。例如，甘地指出，《科学》杂志上的一篇论文发现，SARS-CoV-2引发的免疫细胞在人体内至少能存活8个月。
The findings may help explain why new infections have been falling in Los Angeles County in the wake of a devastating holiday surge. Dr. Roger Lewis, director of COVID-19 hospital demand modeling for the L.A. County Department of Health Services, estimated that about 1 out of 3 people in the county now has immunity to the coronavirus.
这一发现可能有助于解释为什么在灾难性的假期激增之后，洛杉矶县的新感染病例一直在下降。洛杉矶县卫生服务部(L.A. County Department of Health Services) COVID-19医院需求建模主任罗杰·刘易斯(Roger Lewis)博士估计，目前该县约有三分之一的人对冠状病毒有免疫力。
Still, the study authors said more research would be necessary to get a clearer picture about natural immunity to the coronavirus.
尽管如此，该研究的作者表示，还需要进行更多的研究，以更清楚地了解对冠状病毒的自然免疫。
“Factors that influence reinfection risk — such as varying viral strains, patients’ immune status, or other patient-level characteristics — should be evaluated in subsequent studies that include follow-up beyond 90 days,” they wrote.
他们写道:“影响再感染风险的因素——如不同的病毒株、患者的免疫状态或其他患者水平特征——应该在包括超过90天随访的后续研究中进行评估。”