Coronavirus reinfection is real, but very rare

Reports of reinfection with the coronavirus evoke a nightmare future. Attacks of illness, helpless vaccines, relentless blockades-endless pandemic.

Case study published on Monday 25 year old man in Nevada, Newly stimulated those fears. An unnamed man became ill the second time he was infected with a virus, a pattern that the immune system should prevent.

However, the news is only because these cases are rare. Experts say: More than 38 million people worldwide are infected with the coronavirus, and as of Monday, less than five cases have been confirmed re-infected by scientists.

Angela Rasmusen, a virologist at Columbia University in New York, said: “This is very small. Compared to the number of cases that have occurred around the world, it’s like a bucket falling in microliter size.

In most cases, the second bout of the virus had mild or no symptoms.But in the case of at least 3 patients, it includes 1 patient Ecuador, The illness was more severe the second time than at the time of the first infection.89 year old woman in the netherlands Died during her second illness..

Akiko Iwasaki, an immunologist at Yale University, said these cases are rare but show that reinfection is possible. I wrote a commentary It accompanies a Nevada case study published in The Lancet Infectious Diseases.

“It’s important to note that some people are re-infected, and in some of those cases you get a worse illness,” said Dr. Iwasaki. “Once you recover from this infection, you still need to keep wearing a mask and extend your social distance.”

We asked experts what is known about reinfection with the coronavirus and what that phenomenon means for the vaccination and pandemic process.

Reinfection with the coronavirus is a rare event.

First, the good news. There seems to be almost no reinfection.

Since then First confirmed case of reinfectionThere were three published cases reported in Hong Kong on August 24th.Report Another 20 Wait for a scientific review.

However, it is impossible to know exactly how widespread this phenomenon is. To identify cases of reinfection, scientists need to look for significant differences in the genes of the two coronaviruses that cause both diseases.

In the United States, where testing was a rare resource many times this year, many people were not tested unless they were ill enough to be hospitalized. Still, those samples are usually not stored for genetic analysis and it is impossible to confirm suspicious reinfection.

The majority of reinfected people may not be detected. For example, a man in Hong Kong was asymptomatic for the second time and was found infected only by regular screening at the airport.

Marion Pepper, an immunologist at the University of Washington in Seattle, said: “Many people are asymptomatic, unheard of, and exposed.

People with more severe secondary infections are more likely to be identified as they return to the hospital. However, experts said they are likely to be even rarer.

“If this was a very common event, we would have seen thousands of cases,” said Dr. Iwasaki.

For most people, the immune system works as expected.

Reinfection can occur for a variety of reasons. For example, the initial infection was too mild to generate an immune response, or the immune system was damaged by other health conditions. In some cases, patients may be exposed to a large amount of the virus that has spread the infection before the immune response responds.

According to experts, this variation is fully anticipated and has been observed in patients with diseases such as measles and malaria.

Dr. Michael Mina, a pediatric immunologist at Harvard School of Public Health, said, “If there are no very serious and rare cases of fringes, we will never distribute anything to millions of people. “.

For example, at least two of the re-infected patients in Europe had an impaired immune system, and the 89-year-old woman who died was receiving chemotherapy. In other re-infected patients, genetic factors or lack of certain previous immune exposure may have impaired the body’s ability to fight a second attack.

“Some people don’t respond well to certain pathogens,” said Florian Kramer, an immunologist at Mount Sinai School of Medicine. “What is the cause? I’m not sure, but it’s usually rare.”

According to experts, in the majority of known infected patients, the immune system is functioning normally against other pathogens.

“There are many different infections that can be re-exposed to the virus, but you probably don’t know because they have no symptoms,” said Dr. Pepper. “And that may be an important part of boosting immunity.”

When the body is exposed to an unfamiliar virus, it usually develops some immunity first and then increases its response with each exposure. This phenomenon is well known among children, but it is rarely seen in adults because new viruses are rarely encountered, Dr. Mina said.

“I think it’s important to recognize that reinfection is literally integrated into the evolution of our immune system,” he added. “We sometimes lose track of it because so many people who haven’t actually studied the immune system are talking about this.”

Recurrence of symptoms does not prove reinfection.

All confirmed cases of reinfection appear to have recovered from the illness, but there are dozens of cases of infected individuals who have re-affected after weeks or months.

In these cases, important data such as confirmed lab diagnostics and sequenceable virus samples are usually missing.

“The question is always, is it a real reinfection?” Dr. Kramer said. “Obtaining such data is often very difficult.”

Most of these cases are unlikely to be a true infection. More likely, these are people who are experiencing a recurrence of symptoms associated with the original infection. The virus causes an inflammatory response that burns up after a few weeks and can cause symptoms such as fatigue and heart problems. In rare cases, some patients develop chronic low-grade infections caused by the virus, but they do not disappear completely.

“Even viruses that can cause acute infections, such as the flu, can develop persistent infections if the immune system is sufficiently compromised,” said Dr. Kramer. ..

Although these are not true reinfections, Dr. Rasmussen said he is still worried about whether they will lead to new illnesses or hospitalization months after the initial infection. “If recurrences occur frequently and people are seriously ill for the second time, it’s a potential problem of their own,” she said.

People with a second seizure can infect others with the virus.

Even asymptomatic re-infected people can infect others with the virus. For example, a patient in Hong Kong was quarantined in a hospital even though he had no symptoms. However, his viral load was high enough that he should have been able to pass the virus on to others.

“Obviously, the person wasn’t ill, so it’s a good sign for him, but not a good sign for the community,” Dr. Pepper said.

However, researchers may need to look for live viruses to ensure infectivity. Korean researchers were able to investigate hundreds of reports of reinfection and exclude them as actual cases after failing to propagate the infectious virus from the sample.

Dr. Rasmussen said similar steps would be needed to rule out the possibility of infection in each patient, adding that “I think that’s the only way you can get to that root.” ..

Vaccines may be important to prevent reinfection.

Reports of reinfection have raised concerns about whether coronavirus vaccines are effective and help communities achieve herd immunity. The concern is that the immunity produced by the vaccine is not sufficient to prevent reinfection by the virus.

In fact, experts say that vaccines are more likely to produce stronger immunity than natural viral infections.

Coronaviruses, for example, are particularly good at fending off early immune alerts in the body and buy valuable time to sow the infection. In some people, this delay ultimately causes a chain of immune overreactions that can be more harmful than the infection itself.

Vaccines are intended to spread the immune response without interference from the virus, thus avoiding this inflammatory sequence. Vaccines can also be manipulated to enhance immune memory. This provides a more lasting and protective response.

Vaccine trials are designed to look for disease-free rather than infection, and it is unclear whether the vaccine can suppress virus levels sufficient to prevent transmission to others.

Still, vaccine-induced immunity should be superior to innate immunity, Dr. Rasmussen said, adding that “I am optimistic.”