Can you catch the coronavirus twice? What's known about immunity

Those recovering from the coronavirus are unlikely to catch it at least in the short term, experts say. However, it is unclear how long this immunity lasts.

“It is reasonable to predict that we will have some immunity. To say that you will have lifelong immunity? We just don’t know yet,” said Frances Lund, professor and chair of the Department of Microbiology at the University of Alabama in Birmingham. “But I think it’s a reasonable conclusion that you’ll have immunity for the rest of this season.”

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The key to immunity lies in the antibodies produced by people who have recovered from COVID-19, the disease caused by the coronavirus.

Antibodies are proteins in the bloodstream that attack foreign invaders such as viruses and bacteria. Those that are produced in response to the coronavirus may one day serve as a guide to public health measures, such as: B. as a signal when it is safe for a person to end social distancing. They are also being used to treat critically ill patients whose own antibodies are insufficient to ward off the virus.

Further testing is needed in both areas, but in the meantime, senior health officials have expressed confidence that coronavirus antibodies are likely to prevent a person who has had the infection from developing it a second time.

“I am very confident that if this virus behaves like any other virus that we know of, you will have an immunity that will protect you from re-infection. Once you get infected, get better and get rid of the virus.”

“We don’t know 100 percent because we didn’t do the study,” said Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases. told “The Daily Show” host Trevor Noah last week. “But I am very confident that if this virus behaves like any other virus that we know of, you will have an immunity that will protect you from re-infection. Once you get infected, get better and get rid of the virus.”

Whether this protection will be long-term depends on a number of factors, experts say.

The first is whether the virus mutates. If it remains stable, those who have had it have a high chance of being able to “stop it at the door” if they are exposed to it a second time because the antibodies in their blood recognize it and prevent it from getting in her blood increased body, said Lund.

However, the corona virus is an RNA virus, ie its genetic material consists of RNA and not DNA. And RNA viruses tend to mutate over time: seasonal influenza, another RNA virus, usually changes from year to year.

“That’s why there’s a new flu vaccine every year,” said Dr. Tim Schacker, infectious disease doctor and vice dean of research at the medical school at the University of Minnesota. “Influenza has always been here. You make antibodies against some parts of the virus all the time, but it’s the novel parts of the virus that you want antibodies against.”

Since this “corona virus is a brand new virus,” said Schacker, everyone is susceptible to every part of it.

The other factor in preventing re-infection is how good are the antibodies that humans make against the coronavirus. Humans almost always produce antibodies when exposed to a virus. But not every antibody is strong enough to prevent a virus from re-infecting cells – and scientists have yet to find out whether the coronavirus antibodies are high-quality antibodies.

“Do they neutralize the virus, which means that it binds to a specific location on the virus that prevents the virus from attaching to the cell that it would normally infect?” Lund said.

Even if the antibodies are able to do so, the immunity they provide may deteriorate over time.

“Because this is so new, it is difficult to predict what will happen,” said Joel Baines, virologist at Louisiana State University. “There will be a period of immunity, and it can only take eight months to a year and several years.”

“All of this is in your garden strain infection. We just don’t know yet what will happen to this infection.”

This period is called immunological memory, Schacker said, and depends on the plasma cells that cause antibodies to divide and stay in your blood for some time.

“So if you are exposed to this pathogen again and you have enough cells to produce antibodies, you are protected from re-infection,” he said. “But all of this is in your garden infection. We just don’t know yet what will happen with this infection.”

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There are hopeful signs of the quality of the coronavirus antibodies that the body produces. Study treatments using convalescent serum or antibody-rich plasma donated by recovered coronavirus patients have shown promise in very sick patients – so much so that New York governor Andrew Cuomo announced a plan to use experimental treatment in his state, the most affected in the United States, to save lives.

The serum works by providing patients with their own antibodies to the coronavirus, and can also give their immune system a break, which can reduce some of the inflammatory response it triggered to the virus, Lund said.

While preliminary results make scientists seem optimistic, experts warn that further studies are needed before conclusions can be drawn about the coronavirus and immunity.

“Viruses have been around for a very, very long time and they are not stupid,” said Lund. “They figured out what to do to thrive.”

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