哪些人天生不会感染新冠？
2022-12-23 11:41阅读：
2022年年末，外界所预期的季节性新冠肺炎病例数量增长开始出现，美国7天平均新增死亡病例比两周前增长了65%。然而，围绕疫情最令人感到困惑的地方依然存在：有人从来不感染新冠。
抵御病毒的重要方式
虽然有许多人可能是通过采取预防措施或简单的运气使其避免了感染，但科学家们认为，的确存在从来不感染新冠的人，他们天生就对新冠病毒免疫，而他们的基因则可能包含着治疗新冠的线索。有人天生对一些病毒免疫。最明显的例子便是艾滋病，某种基因突变会使一些人免于感染艾滋病，这是少数艾滋病患者被治愈的关键。
而那些从来不得新冠的人体内是什么样子呢？我们现在还不确认。人体抵御病毒的方式之一是基因突变。例如，冠状病毒需要同细胞表面的ACE2受体结合，才能入侵细胞。如果你的ACE2受体存在突变，病毒就无法入侵你的细胞，也就无法感染你。但这种突变可能很罕见。
基因也会影响人们患病的严重程度。有人先天免疫系统存在突变，它就像是你免疫系统的第一响应者。更具体的反应，如针对特定病毒的抗体，会在感染后出现。第一响应者系统存在突变的人们似乎病症会很严重。另一方面，也有一些突变能让一些人免于感染。
以不会感染的人为研究对象
那些无症状的人同样也感染了病毒。病毒存在于他们体内，他们没有明显的症状，或者症状很轻微。但这与那些根本不会感染的人不是一回事。不过，研究人员很难追踪这两组人群之间的差异，因为很多人现在已经感染了。
许多人可能会想：“哦，我对病毒免疫了。我还没有感染，科学家应该对我进行研究。”一些研究人员的确开始对那些未感染新冠病毒的人进行研究。但奥密克戎变异毒株很快出现，几乎每个人都被感染了。一些科学家感到很受挫折，他们必须从头来过。研究过程可能需要更长时间，因为科学家必须以那些真正不会感染的人
为研究对象。一些科学家正在对那些本应感染却未感染的医护工作者和看护者进行研究，希望从中可以找出治疗新冠肺炎的办法。
事实上，我们并不知道有多少人永远不会感染新冠病毒，因为存在太多未知因素。我们不知道，那些说自己从未感染的人是否真的没有感染过，或者他不知道自己已经感染。我们也不知道，他们是否防护措施很严格，导致病毒没有机会传染。再加上，疫苗起到了一些针对感染的免疫作用。真正完全免于新冠病毒感染的人们的数量或许非常少。
他们为何避免感染
我们向人们询问到目前为止是如何避免感染新冠病毒的，收到超过1万份回复。比如，来自纽约布鲁克林的杰西卡说：“疫情期间，我一直在照顾一位患癌症的朋友，一直避免见任何人，以让他感到安全。他今年2月去世，我也开始出门见朋友，但我现在还没有感染。我要么是免疫于新冠病毒，要么就是他变成了我的‘守护天使’。”
来自加州的凯瑟琳说：“健康体质至关重要。疫情之前，我很少感冒，再加上采取了预防措施，戴口罩，注射疫苗和加强针，居家办公，加上一些运气。两年半来，我甚至没有流过鼻涕。我们现在已经抛开口罩，开始堂食，社交和定期举办派对。”
来自日本冲绳的吉莉安说：“我想，我和丈夫没有感染新冠病毒主要是运气使然。我们没有孩子，社交圈子很小，大家对如何安然度过疫情的观点都很一致。我们在疫情开始时住在怀俄明州，那里人口不密集。后来，我们搬到冲绳，融入到公共卫生健康大于个体自由的文化中。这里的人都戴口罩，我们也更容易地保持了这一习惯，这让我们在过去3年中一直保持安全和健康。”
来自德国埃森市的茱莉亚说：“我免疫功能低下，知道自己必须尽一切可能不要感染。疫情第一年，我几乎都生活在隔离状态中。之后，我一直戴着FFP2防护口罩工作，从不坐公交车或火车，也从来不会不戴口罩进入超市，一直避免去那些高感染风险的地方。我完成了全程疫苗接种。即便现在，我在公共场合也经常戴口罩。周围的人也一直努力让我保持安全，在来看我之前会自我检测。我很感谢他们。”
Who Are the 'Never-Coviders'?
Plus your experiences without Covid.
By Jonathan Wolfe and Whet Moser
Today’s Virus Briefing is the last one for 2022. The year began as
the surge in the Omicron variant in the U.S. was nearing its peak:
On Jan. 20, nearly 160,000 Covid patients were hospitalized, the
most at any point in the pandemic. On Feb. 2, the seven-day average
of new reported deaths peaked at 2,669.
As the year comes to a close, an expected seasonal increase in
Covid cases has begun. The seven-day average of daily deaths is up
65 percent from two weeks ago. With cases of the flu and
respiratory syncytial virus, or R.S.V., also high, several cities
and counties, including New York City and Los Angeles, have advised
people to mask up.
But one of the most confounding mysteries of the pandemic remains:
Some people have never had Covid, this season or ever.
While many people may have avoided infection through precaution or
luck, “never Coviders,” scientists believe, are truly out there:
People who are naturally immune and whose genetics could hold clues
for treatment.
Jonathan Wolfe spoke with Times colleague Apoorva Mandavilli about
how scientists are trying to find them, and what we might
learn.
Does this really happen?
It probably is a real thing. There are other viruses for which we
know there are people who are naturally resistant. The most
striking example I can think of is H.I.V., where there is a
mutation that makes some people resistant to getting infected with
the virus. That’s actually been the key to curing the very few
people that have been cured of H.I.V.
What’s going on inside people who have never gotten Covid?
We don’t know for sure.
One way for the body to be resistant to a virus is through genetic
mutations. So, for example, the coronavirus needs what’s called an
ACE2 receptor on a cell in order to latch on to it. If you have a
mutation in that particular receptor, then the virus can’t get into
your cells and can’t infect you. But that kind of mutation is
likely to be pretty rare.
Genetics also plays a role in how severely people get sick. Some
people have mutations in the innate immune system, which is like
the first responder part of your immune system and is pretty
generic. More specific reactions, like antibodies for a particular
virus, appear later in an infection.
We know now that people who have mutations in that first responder
system tend to have very severe disease. So the flip side is also
likely to be true: Some people may have mutations that prevent them
from getting infected at all.
Couldn’t they just be asymptomatic?
People who are asymptomatic are still infected. The virus is in
their bodies, but they have no visible symptoms, or really mild
symptoms. That’s very different from what we’re talking about here
— somebody who doesn’t get infected at all. But it’s been really
difficult for researchers to home in on the difference between
these two groups, because so many people have been infected by
now.
What do you mean?
There were a lot of people who thought, “Oh, I’m immune to the
virus.” I’ve even had friends say that to me: “I haven’t gotten it
yet. Scientists should study me.” Some researchers did begin
studying people who had not gotten Covid. But then Omicron came
along and infected nearly everyone. Some scientists were very
frustrated because they basically had to start over. On the other
hand, those people were not “never Coviders” anyway. So the studies
may take longer, but they’ll be based on people who truly can’t get
infected.
Some scientists are studying health care workers and caregivers who
really should have gotten infected because they had such high
exposure, but didn’t. The idea is that knowing what causes somebody
to not get infected might help us figure out treatments for
infection.
How many true “never Coviders” are there?
We don’t know because there are so many unknowns. We don’t know if
all the people who say they haven’t gotten it yet really haven’t
had it, or had it and didn’t know. We also don’t know if they’ve
just been incredibly careful and so the virus just hasn’t had a
chance to infect them yet.
Also, things got complicated after the vaccines were introduced
because the vaccines gave some immunity against infection. But the
actual number of people who are totally immune to the virus, for
whatever reason, is probably pretty small.
What if I’ve never been infected?
If you haven’t gotten it yet, that’s wonderful and you’re lucky,
either because you’re genetically lucky or because you’ve managed
to dodge the virus. But I wouldn’t assume that you are naturally
resistant and throw all precautions to the wind. The chances you’re
naturally immune are fairly low. And as Omicron shows, it may be
that you just haven’t met the right variant yet.
Your ‘never Covid’ experiences
We asked you how you think you might have avoided Covid so far, and
got over 10,000 responses.
“I spent the pandemic taking care of a friend with cancer and
avoided everyone just to focus on him and make him feel safe. He
passed away in February and I started going out again and seeing
new people, but I still haven’t caught it! Either I am immune or I
have a Covid guardian angel (him).” — Jessica Choe, Brooklyn,
N.Y.
“Healthy constitution. Rarely got colds or flu even before the
pandemic, plus early precautions, masking, vaccines, boosters,
working from home and luck. Two and a half years with nary a
sniffle, so we’ve given up our masks, dine indoors, socialize and
party regularly now. Probably jinxing myself as I type.” —
Katherine Fife, Davis, Calif.
“I think neither my husband nor I have caught Covid mostly due to
luck. We don’t have kids. We maintain a small, close circle of
friends that shared the same views on how best to navigate the
pandemic. We also had the benefit of living in Wyoming at the start
of the pandemic, a place that isn’t densely populated. We’ve since
moved to Okinawa, Japan, and have become embedded in a culture that
prioritizes public health and welfare over the individual.
Mask-wearing is normal here, making it easier for us to continue
the habits that have kept us safe and healthy these past almost
three years.” — Jillian, Okinawa, Japan
“I have no idea. Stupid luck? Providence? l quarantined in the
basement when my husband had it (mildly) in January 2021. He now
suffers from PASC, or long Covid, and it has forever changed and
devastated our lives.” — Malia Schaefer, Cincinnati
“Because I’m immunocompromised, I knew I had to do everything I
could to not get infected. In the first year of the pandemic, I
almost exclusively lived in quarantine. From then on, I always
worked with an FFP2 mask, never took the bus or train, was never in
the supermarket without a mask and avoided places with a high risk
of infection. I have all vaccinations. Even today, I always wear a
mask in public facilities. Those around me tried keeping me safe,
always testing themselves before they came to see me. I am very
grateful for that.” — Julia Litschke, Essen, Germany
“I was sent home to WFH early in the pandemic because I had just
finished chemo and radiation. I’ve been working remotely for two
years now. I also got the vaccine as soon as it was available. I’ve
gotten every booster, including the bivalent vaccine. My mask
protocol is: Check your surroundings. Is there a ceiling? Wear a
mask. Is there a crowd? Wear a mask. Neither? Take it off. That
being said, I suspect I have been infected but was asymptomatic or
mistook it for an allergy.” — Kim Haas, Pittsburgh
