從冠狀病毒中恢復的人是否獲得了免疫力

從冠狀病毒中恢復的人是否獲得了免疫力

It's unclear whether people who recover from COVID-19 will be immune to reinfection from the coronavirus and, if so, how long that immunity will last.

目前還不清楚從COVID-19恢復的人是否對冠狀病毒的再次感染有免疫力，如果有的話，這種免疫力能持續(xù)多久。

"We don't know very much," says Matt Frieman, a coronavirus researcher at the University of Maryland School of Medicine in Baltimore. "I think there's a very likely scenario where the virus comes through this year, and everyone gets some level of immunity to it."

巴爾的摩馬里蘭大學醫(yī)學院冠狀病毒研究員馬特·弗里曼說：“我們知道的不多。”我認為，很有可能出現(xiàn)這樣的情況：病毒今年會過去，每個人都會對它有一定程度的免疫力。”

"That is the hope," he adds. "But there is no way to know that."

“這是一種希望，”他補充道。“但是沒有辦法知道。”

Researchers do know that reinfection is an issue with the four seasonal coronaviruses that cause about 10 to 30 percent of common colds. These coronaviruses seem to be able to sicken people again and again, even though people have been exposed to them since childhood.

研究人員確實知道，四種季節(jié)性冠狀病毒的再次感染是一個問題，導致大約10%到30%的普通感冒。這些冠狀病毒似乎能夠使人一次又一次地患病，盡管人們從小就接觸到它們。

"Almost everybody walking around, if you were to test their blood right now, they would have some levels of antibody to the four different coronaviruses that are known," says Ann Falsey of the University of Rochester Medical Center.

羅徹斯特大學醫(yī)學中心的安·法爾西說:“幾乎所有在街上行走的人，如果你現(xiàn)在檢測他們的血液，你會發(fā)現(xiàn)他們對已知的四種不同的冠狀病毒都有不同程度的抗體。”

After infection with one of these viruses, she says, antibodies are produced but then the levels slowly decline and people become susceptible again.

她說，在感染了其中一種病毒后，會產生抗體，但隨后抗體水平會慢慢下降，人們再次變得容易感染。

"Most respiratory viruses only give you a period of relative protection. I'm talking about a year or two. That's what we know about the seasonal coronaviruses," says Falsey.

“大多數(shù)呼吸道病毒只給你一段相對的保護期。我說的是一兩年。這就是我們對季節(jié)性冠狀病毒的了解，”法爾西說。

In studies, human volunteers who agreed to be experimentally inoculated with a seasonal coronavirus showed that even people with pre-existing antibodies could still get infected and have symptoms.

在研究中，同意接受季節(jié)性冠狀病毒接種實驗的人類志愿者表明，即使是已經有抗體的人也可能被感染并出現(xiàn)癥狀。

That happens even though these viruses aren't as changeable as influenza, which mutates so quickly that a new vaccine has to be developed every year.

即使這些病毒不像流感那樣易變，也會發(fā)生這種情況。流感的變異速度非常快，每年都要研發(fā)出一種新的疫苗。

"We work with some common cold coronaviruses. We have samples from 30 years ago, strains that were saved from 30 years ago, and they're not appreciably different than the ones that are circulating now," says virologist Vineet Menachery of the University of Texas Medical Branch in Galveston.

“我們研究一些普通的感冒冠狀病毒。我們有30年前的樣本，30年前保存下來的毒株，它們與現(xiàn)在流通的毒株沒有明顯的不同，”加爾維斯頓德克薩斯大學醫(yī)學分部的病毒學家維內特·梅納赫里說。

Still, seasonal coronaviruses probably do mutate a bit over time to evade the body's defenses, says Frieman. But there's little known about what those changes might look like, since researchers don't do annual surveillance of coronaviruses as they do for influenza.

不過，季節(jié)性冠狀病毒可能會隨著時間的推移發(fā)生一些變異，以逃避人體的防御，弗里曼說。但是，由于研究人員不像對流感病毒那樣對冠狀病毒進行年度監(jiān)測，人們對這些變化的情況知之甚少。

It's also possible that, for some reason, the body's immune response to seasonal coronaviruses is just not that robust or that something about the infection itself may inhibit the body's ability to develop long-term immunity.

也有可能，由于某種原因，人體對季節(jié)性冠狀病毒的免疫反應不是那么強烈，或者是感染本身的某些因素可能會抑制人體形成長期免疫的能力。

"Maybe the antibodies are not protective and that is why, even though they are present, they don't work very well," says Frieman.

“也許抗體并不能起到保護作用，這就是為什么即使它們存在，它們也不能很好地起作用，”弗里曼說。

The other known human coronaviruses, SARS and MERS, can cause more severe disease, and basically nothing is known about the possibility of reinfection with those viruses.

其他已知的人類冠狀病毒，如非典和中東呼吸綜合征，會導致更嚴重的疾病，基本上我們對這些病毒再次感染的可能性一無所知。

"We've gone back and gotten samples from patients who had SARS in 2003 and 2004. and as of this year we can detect antibodies," says Stanley Perlman of the University of Iowa. "We think antibodies may be longer lasting than we first thought, but not in everybody."

愛荷華大學的斯坦利·帕爾曼說：“我們已經從2003年和2004年的SARS患者身上采集了樣本，從今年起，我們可以檢測出抗體。”我們認為抗體的持續(xù)時間可能比我們最初想象的要長，但不是每個人都這樣。”

Still, it's hard to predict how those survivors' bodies would react if they were exposed to the SARS virus again. "There were 8.000 cases, the epidemic was basically brought to an end within six months or eight months of the first case, so we don't have anyone who was reinfected that we know of," says Perlman.

然而，很難預測如果這些幸存者再次暴露在非典病毒下，他們的身體會有什么反應。帕爾曼說:“當時有8000個病例，疫情基本上在第一個病例出現(xiàn)后的6個月或8個月內就結束了，所以據我們所知，沒有人再次被感染。”

Understanding the natural immune response to this virus is important for vaccine development, he notes.

他指出，了解這種病毒的自然免疫反應對疫苗的開發(fā)很重要。