When people ask how to prevent the spread of COVID-1

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The otherwise healthy 25-year-old man from Nevada was the first American to be confirmed to have caught COVID-19 twice, with the second infection worse than the first.

He has recovered, but his case raises questions about how long people have been protected after being infected with the coronavirus that causes the disease and potentially how protective the vaccine can be.

“It’s a yellow light for caution,” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University School of Medicine in Nashville, Tennessee, who was not involved in the study.

Respiratory infections such as COVID-19 do not provide lifelong immunity like measles. So Dr. Paul Ofit, an infectious disease expert at Children’s Hospital of Philadelphia, said he was not at all surprised that people could be infected twice with the coronavirus, SARS-CoV-2.

It is too early to know whether the man from Washo County, Nevada, who had no known health problems other than a double infection, was extremely uncommon or whether many people could easily become infected with SARS-CoV-2 more than once. said Schaffner.

“There is hardly an infectious disease doctor in the country who has not met a patient who thinks he has had a second infection,” he said. “Whether that’s true or not, we don’t know. There are a lot of respiratory infections out there.”

How rare is it?

There have been at least 22 documented cases of reinfection worldwide since the pandemic began, but it is unclear how many there actually are and how often they may be among people who don’t even know they are infected.

“It could be an event in a million, we don’t know,” said Akiko Iwasaki, an immunologist at Yale University and an investigator at the Howard Hughes Medical Institute, who commented on the study.

With millions of infected people, it is difficult to know whether cases like the new one are very rare events or the tip of the iceberg, she said. “It is possible that most people are completely protected from reinfection, but we do not measure them because they do not come to the hospital.”

In addition, many people do not know that they are infected for the first time, so it is difficult to say whether they are re-infected.

In one recent case, a Hong Kong man only knew he had been reinfected because he was caught during a routine screening when he returned from abroad, months after clearing an infection and receiving a negative test.

One reason there are no more documented cases of reinfection: It’s hard to prove, said Mark Pandori, a pathologist at the University of Nevada, Reno Medical School and senior author of the new study.

His team coordinated at the start of the pandemic with members of the Washo County Health District to look for re-infections. They had the advantage of sequencing equipment on campus, as did microbiologists, he said. And they were lucky to find someone who had been tested both times for being infected and cleared between them.

Why his infection was worse for the second time remains unclear, said Pandora, director of the State Public Health Laboratory in Nevada. “I can’t tell you if it tells us anything specific about the biology of this virus.”

The man caught a slightly different version of the virus for the second time, according to a genetic analysis of the man’s infections. It is possible that the second version was more dangerous, although there is no evidence of this, or that it was different enough that his body did not recognize it, the newspaper writes.

Consequences for vaccination

Iwasaki said the study raises questions about how long immunity lasts after a natural infection. Vaccine protection is likely to be very different, she said.

“Vaccines can be designed to cause much higher levels of antibodies and much longer-lasting immunity,” she said. Just because a natural infection doesn’t protect you doesn’t mean vaccines can’t. This is a separate issue. “

Ofit, also a vaccine expert at Perelman School of Medicine at the University of Pennsylvania, said he expects vaccine protection to last at least a year or two.

The protection provided by infection or vaccination is not 100% perfect until the day it disappears completely, he said. Instead, the protection is gradually fading, so someone exposed to a huge dose of the virus can be reinfected within months, while others can be protected for years, Ofit said.

It is also possible that the Nevada man has an undiagnosed problem with his immune system. “He should probably be seen by an immunologist,” Ofit said.

The length of time the infection will be defensive remains one of the key open questions about the virus.

Infected twice, with an interval of two months

The Nevada man, considered a major worker, began feeling unwell in late March with a sore throat, cough, headache, nausea and diarrhea. His workplace was affected by an outbreak at the start of the pandemic before safety measures such as masks could be introduced, said Heather Kervin, a senior epidemiologist in the Washo County Health District and co-author of the newspaper.

He went for tests on April 18 and his coronavirus infection was confirmed.

On April 27, he announced that his symptoms had resolved and he was feeling well, but at that time, employees had to take a negative COVID-19 test twice before being returned to work, Kervin said. So he was left isolated at home.

A month later, he began to feel unwell again. At the same time, there was an outbreak where one of his parents, also a key worker, was hired, Kervin said.

On May 31, he went to an emergency center, reporting fever, headache, dizziness, cough, nausea and diarrhea. On June 5, he went to a doctor, who found that his oxygen levels were dangerously low and ordered him to be hospitalized. Again, the man was positive for the virus, although he still had antibodies to the virus in his blood, Kervin said.

The genetic differences between the viruses responsible for each of his infections suggest that he was infected twice. The virus did not mutate quickly enough within a single person to explain the differences between the two infections, the researchers found.

A parent living with the man also caught COVID-19 and was diagnosed on June 5.

The newspaper reports that the man may have been re-infected because he was exposed to a higher dose of the virus for the second time, perhaps by a family member.

His cough continued and he suffered from shortness of breath and mental fog and was on oxygen for six weeks after the second infection, Kervin said. Now he has fully recovered.

Reinfections suggest the so-called. Herd immunity cannot be obtained by natural infection alone. If the natural infection only protects for a few months, then it will be impossible for enough people to be protected at the same time to reach herd immunity.

The moral of the case, said co-author Pandora, is that even people who have already been sick with COVID-19 should protect themselves by wearing a mask, avoiding large gatherings, washing their hands often and maintaining social distance.

“We’re not invulnerable to that,” Pandora said. “You can actually make it worse a second time.”

Contact Karen Weintraub at and Elizabeth Wise at

Patient health and safety coverage at USA TODAY is made possible in part through a grant from the Masimo Foundation for Health Ethics, Innovation and Competition. The Masimo Foundation does not provide editorial data.

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