VOA健康报道2023--Researchers Explore Causes of Long COVID

Researchers Explore Causes of Long COVID

A British historian¹, an Italian archaeologist and an American teacher all have something in common.

The three women are credited with describing and naming the condition known as long COVID in early 2020.

Almost three years into the pandemic, scientists are still trying to figure out why some people get long COVID and why a small percentage — including the three women — have lasting² symptoms.

Background

Rachel Pope³, the historian, is from the British city of Liverpool. She posted on Twitter about her symptoms in late March 2020, after a coronavirus infection. A few months later, in Italy, Elisa Perego tweeted about her sickness also and used the term "long COVID" in the post. And, that same year, Amy Watson of Portland, Oregon, founded a Facebook support group for people, like her, who were suffering from long COVID. She identified them as "long haulers," a term used in the trucking industry. The name stuck.

Millions of people worldwide report having long COVID. The symptoms include lung damage, difficulty thinking and remembering, extreme tiredness, and other problems. Evidence suggests most people get better within a year. But recent data show that long COVID has played a part in more than 3,500 U.S. deaths.

Women more likely to suffer from long COVID

Many studies suggest that women are more likely than men to develop long COVID.

There could be biological reasons.

Women's immune⁴ systems generally have stronger reactions to viruses, bacteria, and other germs, said Sabra Klein, an immune system expert at Johns Hopkins University.

Women are also much more likely than men to have autoimmune diseases, where the body mistakenly attacks its own healthy tissue. Some scientists believe long COVID can result from an autoimmune response caused by the virus.

Women's bodies are also more likely to have more fat tissue. New research suggests the coronavirus may hide in fat after infection. Scientists also are studying whether women's changing hormone⁵ levels may increase the risks.

Yet there are other possible issues at work. Women are more likely than men to seek health care, Klein said. She added that often women are more sensitive to changes in their bodies.

"I don't think we should ignore that," she said, adding that biology and behavior are probably both at play.

Other viruses

Several studies suggest the Epstein-Barr virus could play a part in some cases of long COVID.

Epstein-Barr is a very common virus. It has infected an estimated 90 percent of the U.S. population. The virus' effects can differ greatly among those infected. Some patients might develop the disease mononucleosis, for example. Others, however, may not be sickened at all by an Epstein-Barr infection.

Inflammation caused by coronavirus infection can activate⁶ or reactivate some viruses in the body, said Dr. Timothy Henrich. He is an expert with the University of California, San Francisco.

Henrich is among researchers who have found immune markers pointing to Epstein-Barr reactivation in the blood of long COVID patients.

Not all long COVID patients have these markers. But it's possible that Epstein-Barr is causing symptoms in those who do, although scientists say more study is needed.

Obesity⁷

Obesity is a risk factor for severe COVID-19 infections and scientists are trying to understand why.

Stanford University researchers are among those who have found evidence that the coronavirus can infect fat cells. In a recent study, they found the virus and signs of inflammation in fat tissue taken from people who had died from COVID-19.

Lab tests showed that the virus can reproduce⁸ in fat tissue. That raises the possibility that fat tissue could serve as a storage area, possibly fueling long COVID.

Hope and concerns

Dr. Lawrence Purpura is an infectious⁹ disease expert at Columbia University in New York. He said about patients with long COVID, "The majority of patients will eventually recover...It's important for people to know that."

Still, the women who helped the world recognize the condition of long COVID remain concerned about recovery.

Perego developed heart, lung and other problems and remains¹⁰ seriously sick.

The 44-year-old says she knows that scientists have learned a lot in a short time. But, "there is a gap," she said, between long COVID research and medical care.

Watson, who is 59, says she has "never had any kind of recovery." She experiences severe headaches, digestive trouble and nerve and foot problems. Recently she developed anemia¹¹.

She wishes the medical community had a more organized process for treating long COVID. Doctors say not knowing the underlying¹² cause or causes makes that difficult.

"I just want my life back," Watson said, "and it's not looking like that's all that possible."

Words in This Story

symptom -- n. a change in the body or mind which indicates that a disease is present

immune -- adj. of or relating to the body's immune system

autoimmune – adj. of, relating to antibodies or T cells that attack molecules¹³, cells, or tissues of the organism producing them

hormone – n. a natural substance that is produced in the body and that influences the way the body grows or develops

anemia – n. medical: a condition in which a person has fewer red blood cells than normal and feels very weak and tired

1 historian   

n.历史学家，编史家

参考例句：

• As a historian,he was most typical of the times in which he lived.作为历史学家，他是他所处时代最有代表性的人物。
• He calls himself a historian,but his books are a mere journalism.他自称为历史学家，但是他的书都是些肤浅的通俗作品。

2 lasting   

adj.永久的，永恒的；vbl.持续，维持

参考例句：

• The lasting war debased the value of the dollar.持久的战争使美元贬值。
• We hope for a lasting settlement of all these troubles.我们希望这些纠纷能获得永久的解决。

3 pope   

n.（罗马天主教的）教皇

参考例句：

• The Pope is the spiritual leader of many Christians.教皇是众多基督徒的宗教领袖。
• The Pope is the supreme leader of the Roman Catholic Church.教皇是罗马天主教的最高领袖。

4 immune   

adj.免疫的，有免疫力的，不受影响的，免除的

参考例句：

• I am immune from the disease,for I had it once.我对这病有免疫力，因为我已得过一次了。
• Be immune from corruption.拒腐蚀，永不沾。

5 hormone   

n.荷尔蒙，激素，内分泌

参考例句：

• Hormone implants are used as growth boosters.激素植入物被用作生长辅助剂。
• This hormone interacts closely with other hormones in the body.这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。

6 activate   

vt.使活动起来，使开始起作用

参考例句：

• We must activate the youth to study.我们要激励青年去学习。
• These push buttons can activate the elevator.这些按钮能启动电梯。

7 obesity   

n.肥胖，肥大

参考例句：

• One effect of overeating may be obesity.吃得过多能导致肥胖。
• Sugar and fat can more easily lead to obesity than some other foods.糖和脂肪比其他食物更容易导致肥胖。

8 reproduce   

v.生育，繁殖，复制，重做

参考例句：

• The machine can reproduce a key in two minutes.这机器能在两分钟内复制一把钥匙。
• The picture will reproduce well.这照片会印得很清楚。

9 infectious   

adj.传染的，有传染性的，有感染力的

参考例句：

• Influenza is an infectious disease.流感是一种传染病。
• What an infectious laugh she has!她的笑声多么具有感染力啊！

10 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

11 anemia   

n.贫血，贫血症

参考例句：

• The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。
• I was put on iron tablets for my anemia.我曾因贫血吃补铁药片。

12 underlying   

adj.在下面的，含蓄的，潜在的

参考例句：

• The underlying theme of the novel is very serious.小说隐含的主题是十分严肃的。
• This word has its underlying meaning.这个单词有它潜在的含义。

13 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。