A 33-year-old man was infected with the coronavirus more than four months after his first attack, the first documented case of so-called reinfection, researchers in Hong Kong reported Monday.
The finding was not unexpected, especially considering the millions of people worldwide are infected, experts said. And the man had no symptoms the second time around, suggesting that although the previous exposure did not prevent reinfection, his immune system kept the virus in check somewhat.
“The second infection was completely asymptomatic – his immune response prevented the disease from getting worse,” said Akiko Iwasaki, a Yale University immunologist who was not involved in the work but reviewed the report at The New York Times’ request. . “It’s kind of an example of a textbook on how immunity should work.”
People who have no symptoms can still spread the virus to others, however, which underscores the importance of vaccines, said Drs. Iwasaki. In the man’s case, she added, “natural infection created immunity that prevented disease but did not re-infect.”
“To provide herd immunity, a potent vaccine is needed to induce immunity that prevents both reinfection and disease,” said Drs. Iwasaki.
Doctors have reported several cases of presumed reinfection in the United States and elsewhere, but none of these cases have been confirmed with rigorous testing. Recovered people are known to carry viral fragments for weeks, which can lead to positive test results in the absence of live virus.
However, Hong Kong researchers sequenced the virus from both male infections and found significant differences, suggesting that the patient was infected a second time.
“I believe this is the first reported case to be confirmed by genome sequencing,” said Dr. Kelvin Kai-Wang To, a clinical microbiologist at the University of Hong Kong.
The study is published in the journal Clinical Infectious Diseases. The Times received the manuscript from the university.
The man’s first case was diagnosed on March 26, and he had only mild symptoms. In accordance with Hong Kong regulations, he was admitted to hospital on March 29, although his symptoms had subsided, and was released on April 14 only after having twice tested negative for the virus.
He had no detective antibodies after the first attack with the virus. He was again positive for the coronavirus on a detective test on August 15 after a trip to Spain via the United Kingdom; the test was administered at the airport. The man had picked up a strain that was circulating in Europe in July and August, the researchers said.
His infections were clearly caused by different versions of the coronavirus, said Dr. To: “Our results prove that his second infection is caused by a new virus he recently contracted, rather than by prolonged viral contamination.”
Common cold coronaviruses are known to cause re-infections in less than a year, but experts had hoped that the new coronavirus would carry more than its cousins SARS and MERS, which appear to produce protection lasting several years.
It is still unclear how common reinfection of the new coronavirus can be, as few researchers have the virus sequences of each infection.
“We have, so far, documented 23 million cases, but the fact that one of them has recurred at this point could not cause unusual alarm to this day,” said Jeffrey Shaman, an epidemiologist at Columbia University in New York. York.
“However, it remains very, very concerning – and this does nothing to dispel that – that we may be subject to recurrent infection with this virus,” he said.
Dr. Iwasaki was more singing. They found that the man had no antibodies after the first infection, but produced them after the second exposure. Immunity is expected to build up in this way with each exposure to a pathogen, she noted.
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Frequently Asked Questions
Updated August 24, 2020
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What are the symptoms of coronavirus?
- At first, the coronavirus seemed to be a respiratory disease in the first place – many patients had fever and chills, were weak and tired, and coughed a lot. Those who had the sickest bodies had pneumonia as an acute respiratory distress syndrome – causing their blood oxygen levels to plummet – and received additional oxygen. In severe cases, they were placed on ventilators to help them breathe. Today, doctors have identified many more symptoms and syndromes. (And some people do not show many symptoms at all.) In April, the CDC added to the list of early signs sore throat, fever, chills and muscle aches. Gastrointestinal upset, such as diarrhea and nausea, has also been observed. Another telling sign of infection may be a sudden, profound decrease in sensation of smell and taste. Teens and young adults have in some cases developed painful red and purple lesions on their fingers and toes – nicknamed “Covid toe” – but a few other serious symptoms. More serious cases can lead to inflammation and organ damage, even without breathing. There have been cases of dangerous blood clots, stroke and cerebral palsy.
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Why does standing six feet apart help others?
- The coronavirus spreads primarily by drips from your mouth and nose, especially when you cough or sneeze. The CDC, one of the organizations using this measure, bases its six-foot recommendation on the idea that most large droplets that expel people when they cough or sneeze fall within six feet to the ground. But six feet has never been a magic number that guarantees complete protection. Noses, for example, can launch drops much farther than six feet, according to a recent study. It’s a rule of thumb: you need to be the safest to stand six feet apart, especially when it’s windy. But always wear a mask, even if you think you are far enough apart.
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I have antibodies. Am I immune now?
- At the moment, that probably seems like at least several months. There have been horrific accounts of people suffering from what appears to be a second bolt of Covid-19. But experts say these patients may have a prolonged course of infection, with the virus taking a slow toll weeks to months after initial exposure. People infected with the coronavirus typically produce immune molecules called antibodies, which are protective proteins made in response to an infection. These antibodies may last only two to three months in the body, which may seem worrying, but that is perfectly normal after an acute infection progresses, said Dr. Michael Mina, an immunologist at Harvard University. It could possibly get the coronavirus back up, but it is highly unlikely that it would be possible in a short window of time from initial infection or the second time safe.
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I am a small business owner. Can I get relief?
- The incentive bills introduced in March provide assistance to the millions of American small businesses. Those eligible for support are non-profit organizations and organizations with less than 500 workers, including sole proprietorships, independent contractors and freelancers. Some larger companies in some sectors are also eligible. The assistance provided, which is managed by the Small Business Administration, includes the Paycheck Protection Program and the Economic Damage Disaster Program. But many people have not seen payments yet. Even those who have received help are confused: the rules are draconian, and some are stuck on money they do not know how to use. Many small business owners get less than they expected or heard nothing at all.
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What are my rights if I am worried about returning to work?
“Again, it’s what the textbook says should happen,” she said. “If you have second exposure to the same pathogen, you need to raise the antibody, and that’s what happens.”
Most people infected with the coronavirus produce detective antibodies that are expected to protect against the virus. Even people who had only mild symptoms, including this man, may also have immune ‘memory’ in the form of B and T cells that prevent symptoms on second exposure.
“The majority of patients probably have a cocktail of immune responses that activate at second exposure,” said Brian Wasik, a virologist at Cornell University. “This Hong Kong patient also appears to be asymptomatic on second infection, perhaps due to some immune response.”
But the researchers said it was also possible that in some people a second exposure would prove more difficult. “It can not yet be generalized, because there is still a possibility that the second infection may be worse,” said Drs. To.
Building immune memory is no different than stimulating a person’s memory, said Dr. Michael Mina, an immunologist at the Harvard TH Chan School of Public Health.
The initial bout with the new coronavirus is likely to result in ‘non-sterilizing immunity’, but the virus will elicit a stronger response with each exposure, he said: “It is often these second and third exposures that help to improve the memory response solidification for the long term. “
About everything, experts said, it is unclear how often people can be re-infected, and how soon, after an initial attack with the virus.
“That leaves open questions, because one person exhibits a mild reinfection, clearly documented as a distinct strain of the virus, does not in any way provide sufficient evidence,” said Drs. Shaman.
