研究：新冠病毒抗體可能在數月內消失

就在全球科學家積極研發新冠疫苗的時候，英國的一項研究發現，新冠肺炎患者體內的抗體會在數月內消失，而疫苗提供的抗體可能也會如此，這意味着人們無法通過一次性注射疫苗“一勞永逸”。更糟的是，新冠病毒可能會像感冒一樣讓人們每年重複感染。

People who have recovered from Covid-19 may lose their immunity to the disease within months, according to research suggesting the virus could reinfect people year after year, like common colds.

一項研究顯示，新冠肺炎患者康復後可能會在數月內失去對新冠病毒的免疫力，該研究指出，新冠病毒可能會和普通感冒一樣讓人們每年重複被感染。

In the first longitudinal study of its kind, scientists analysed the immune response of more than 90 patients and healthcare workers at Guy’s and St Thomas’ NHS foundation trust and found levels of antibodies that can destroy the virus peaked about three weeks after the onset of symptoms then swiftly declined.

在首個同類型縱向研究中，科學家分析了蓋伊和聖托馬斯國民健康保險信託基金會的90多名患者和醫護人員的免疫反應，發現可以摧毀病毒的抗體水平在症狀出現三週後達到高點，然後就迅速下降。

Blood tests revealed that while 60% of people marshalled a “potent” antibody response at the height of their battle with the virus, only 17% retained the same potency three months later. Antibody levels fell as much as 23-fold over the period. In some cases, they became undetectable.

血液檢測發現，儘管60%的人在和病毒作鬥爭時身體產生了“強有力的”抗體反應，但只有17%的人在三個月後還有同樣強大的抗體。在此期間抗體水平下降到原來的24分之一。在某些情況下，甚至檢測不到抗體。

potent [ˈpoʊtnt]: adj. 有效的；強有力的

"People are producing a reasonable antibody response to the virus, but it’s waning over a short period of time and depending on how high your peak is, that determines how long the antibodies are staying around,” said Dr Katie Doores, lead author on the study at King’s College London.

這項研究的首席作者、倫敦國王學院的凱蒂·多蘿絲博士說：“人們會對病毒產生足夠的抗體反應，但是抗體會在短時間內消退，消退早晚取決於最高點的抗體水平，這決定了抗體能在體內存留多久。”

The immune system has multiple ways to fight the coronavirus but if antibodies are the main line of defence, the findings suggested people could become reinfected in seasonal waves and that vaccines may not protect them for long.

免疫系統有多種方式來抗擊新冠病毒，但如果抗體是主要防線，該研究指出人們可能會在季節性疫情中被再次感染，疫苗也可能無法長時間保護他們。

"Infection tends to give you the best-case scenario for an antibody response, so if your infection is giving you antibody levels that wane in two to three months, the vaccine will potentially do the same thing,” said Doores. “People may need boosting and one shot might not be sufficient.”

多蘿絲說：“感染通常會讓身體產生最強的抗體反應，所以如果感染後的抗體水平在兩到三個月後消退，疫苗可能也會如此。人們也許需要加強針，一針可能不夠。”

Early results from the University of Oxford have shown that the coronavirus vaccine it is developing produces lower levels of antibodies in macaques than are seen in humans infected with the virus. While the vaccine appeared to protect the animals from serious infection, they still became infected and may have been able to pass on the virus.

牛津大學的早期研究結果顯示，牛津正在研發的新冠病毒疫苗在獼猴體內產生的抗體水平比感染新冠病毒的人類體內的抗體水平更低。儘管該疫苗似乎能保護動物免於發展爲重症，但是動物依然會被感染，或許還能傳播病毒。

macaque [məˈkæk]: n. 獼猴，恆河猴；短尾猿

The King’s College study is the first to have monitored antibody levels in patients and hospital workers for three months after symptoms emerged. The scientists drew on test results from 65 patients and six healthcare workers who tested positive for the virus, and a further 31 staff who volunteered to have regular antibody tests between March and June.

倫敦國王學院的這項研究是首個對患者和醫院工作人員在症狀出現後進行爲期三個月的抗體水平監測的研究。科學家採用的測試結果來自新冠病毒檢測呈陽性的65名患者和6名醫護工作者，以及自願在三月到六月間定期進行抗體測試的31名工作人員。

The study, which has been submitted to a journal but has yet to be peer-reviewed, found that antibody levels rose higher and lasted longer in patients who were severe cases. This may be because the patients have more virus and churn out more antibodies to fight the infection.

該研究發現發展成重症的患者體內的抗體能達到更高水平，持續時間也更久。這可能是因爲這些患者體內病毒更多，產生了更多抗體來抵禦感染。這項研究報告已經提交給期刊但還未經過同行評審。

churn out: 快速大量生產

Prof Jonathan Heeney, a virologist at the University of Cambridge, said the study confirmed a growing body of evidence that immunity to Covid-19 is short-lived. “Most importantly, it puts another nail in the coffin of the dangerous concept of herd immunity,” he said.

劍橋大學的病毒學家喬納森·希尼教授說，這項研究和日益增多的證據相吻合，證實新冠病毒的免疫反應是短暫的。他說：“最重要的是，它給羣體免疫的危險概念再次判了死刑。”

But Prof Arne Akbar, an immunologist at UCL, said antibodies are only part of the story. There is growing evidence, he said, that T cells produced to fight common colds can protect people as well. Those patients who fight the virus with T cells may not need to churn out high levels of antibodies, he added.

然而，倫敦大學學院的免疫學家阿恩·阿克巴教授指出，抗體只是抗擊病毒的其中一部分，越來越多的證據顯示，抗擊普通感冒的T淋巴細胞也能保護人們。他補充道，那些用T淋巴細胞抗擊新冠病毒的患者也許不需要產生高水平的抗體。