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Do People From Covid-19 Get Re-Infected?



The positive cases are posing a tough question: who has and has enough antibodies to be immunized; How long will the antibodies protect them? 

When encountering a virus, the body's immune system produces specific antibodies, attacking the pathogen. The common understanding of many people is that after becoming infected with a virus, the patient cannot be reinfected by having an effective "defense line". 

But in fact, this mechanism is much more complicated. The immune system, like the spectrum, has specific antibodies to certain viruses, such as chickenpox or measles. After infection, the likelihood of re-infection is almost zero. Meanwhile, immunodeficiency viruses like HIV often do not have equivalent antibodies.

For nCoV, scientists do not understand the immune system's response to the virus, said George Rutherford, head of the global infectious diseases and epidemiology department at the University of California San Francisco. 
"It will take some time to find the answer," he said
Knowing the level of immunity in people recovering from Covid-19 is the key to helping countries decide whether to lift the blockade or not. 

Many countries are aggressively conducting serological tests, identifying those who are immune to the virus. This is considered an important part of the effort to reopen the economy, so that people can return to normal work. New York State has approved an additional rapid test kit, expected to be widely used in the near future. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, even proposed an "immune certificate" for workers. Similar ideas are also considered by European experts.
But it seems that they have not answered the urgent question left open: How long can antibodies to nCoV exist in the human body and prevent viruses? 

According to Rutherford, in the ideal scenario, a person who once had Covid-19 had lifelong immunity like measles. Thus, when countries achieve "community immunity", the virus will stop spreading. 
"This is hope for Covid-19," said Rutherford. 
 Just hope. The reaction of the immune system to nCoV or any other corona virus, including SARS and MERS, is quite complex. They are characterized by prickly proteins, which allow them to attach to host cells. 
"There is currently no evidence that antibodies protect patients (for a long time). There is nothing proving that people who have the disease can not relapse the virus," said David Walt, professor of pathology at Harvard Medical School. and Brigham Women's Hospital, insisted.
A 1984 study of a corona virus showed that no immune response lasts too long. Accordingly, British scientists infected seasonal influenza viruses with volunteers and conducted vaccinations to monitor the amount of antibody produced. Test results a year later showed that the immune system worked well for the same virus. However, people who are exposed to the (small) mutation of the germ still develop flu symptoms.

Experts conclude that patients may only gain "partial immunity" after infection. Another study, published in 1990, showed that in some people, the level of antibodies drops too quickly after a year. Their immune systems are not even able to fight off the virus that was infected.

In fact, only "neutral antibodies" reduce or prevent viral infections. Others are detectable, but cannot link to kill pathogens.
Experts expect nCoV to have neutralizing antibodies. Many hospitals have conducted blood transfusions containing plasma from people who have recovered from Covid-19 for positive patients. The method still works for critical cases. But it's not clear how long this antibody will remain. 

This week, the number of positive people in Korea continued to increase to 163, according to the announcement of the Centers for Disease Control and Prevention (KCDC). The same phenomenon was recorded in China. 
The World Health Organization (WHO) has also recently announced that no evidence has been found that people who have recovered from nCoV infection have long-term immunity. 

To better understand this, scientists need to do more research on specific cases of nCoV. The result will directly affect the vaccine preparation process, drug testing and decision to blockade orders. 


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