Three years after the pandemic, a select group of people have achieved what once seemed impossible. I have never tested positive for Covid. Scientists around the world are looking for genetic reasons why these people avoided Covid despite being repeatedly exposed to the virus.
Were they born hyperimmune? What is behind the success of avoiding infections like Houdini?
“Mostly luck,” laughs Adam Zimmerman, 40, of Rockville, Maryland. Neither Zimmermann nor his wife and children have tested positive for Covid.
“We’ve done all we can to mitigate and do our best,” Zimmermann said, noting that his family is keeping up to date with the vaccine. .”
ever since March 11, 2020is more than 676 million people Infections have been confirmed all over the world. About 60% of the U.S. population has been infected with her Covid, according to the Centers for Disease Control and Prevention. There could be millions more missed cases because individuals had no symptoms.
Millions of people have been vaccinated and are taking precautions similar to the Zimmermann family, but they are still infected with Covid. breakthrough infection Or weakened immunity.
But scientists believe it’s possible that some people may have never been infected, as they entered the pandemic with a sort of biological armor against the virus that causes Covid.
Now they want to unravel the mysteries hidden in the true ‘Covid dodgers’ immune system.
Is it possible to be immune to Covid?
Dr. Jean-Laurent Casanova, a pediatric immunologist, geneticist, and professor at the Rockefeller University in New York, said: “If we find them, the implications are significant.”
Casanova works with an international team of scientists to Covid human genetic endeavours.
Dr. Andras Spaan, clinical microbiologist on the team, said: “Of course, one of them he’s ACE2,” a gene known to help Covid get into the body.
In theory, some people might have the DNA to do the opposite. That is, preventing ACE2 and other genes from allowing Covid to enter her. If researchers can focus on protective genetic factors, they may be able to develop drugs that prevent infection and further spread of the virus.
The team used saliva samples to study the DNA of volunteers and recruited about 1,000 people worldwide.
Not surprisingly, many of the recruits early in the study eventually tested positive for the virus, especially after the highly contagious Omicron took hold in 2022.
Some patients never get infected, Spahn said, “even after repeated intense exposures in microns.”
Rachel Zucker-Wong, 29, from San Francisco tells a similar story. She recalled sitting next to a man at her wedding dinner in September 2021 as the “supercontagious” Delta variant was causing cases nationwide.
“We were sitting right next to him. We were hugging him. We were all toasting,” Zucker-Wong said. “And I never got it.”
In fact, despite her husband contracting Covid and being repeatedly exposed to the virus as a nursing school student, she has never tested positive.
Brian Peach worked as a nurse in the Covid intensive care unit at the Orlando Regional Medical Center in Florida during the early days of the pandemic before a COVID vaccine was widely available.
“We were always in the patient’s room, giving them medicine and keeping their blood pressure up,” said Peach, who is also an assistant professor of nursing at the University of Central Florida. They had regular oral care to prevent respiratory-associated pneumonia.”
He has never tested positive and is fascinated by the idea that he has some sort of protective DNA.
“I would like to know if there is anything in particular that has helped other than the vaccine,” Peach said.
Not that I’ve never heard of it. Some people have genes that protect them from other viruses such as HIV. This discovery has led to a small number of cases in which people living with HIV may have been cured with stem cell transplants from naturally resistant donors.
Early in the pandemic, British scientists intentionally tried to infect people to see what would happen.
of Human Challenge Program It was small, containing only 36 healthy young men and women. Researchers at Imperial College London squirted a small amount of the virus into the participants’ noses and then waited. )
Over 3 Years: Latest Covid News
Half of the participants became infected and experienced mild symptoms. The other half remained infection-free despite having Covid literally put into their nasal passages.
But as the pandemic progressed, most participants eventually developed infections, said Peter Openshaw, a professor of experimental medicine at Imperial College London who led the study.
In other words, inborn Covid immunity was unlikely.
“I don’t think there was anything inherently preventing them from getting infected,” Openshaw said.
Presumably, “very low concentrations of the administered virus were engulfed in mucus masses and shed rather than entering and causing infection,” Openshaw said.
Exposed to Covid but no symptoms
As the search for elusive immune genes continues, asymptomatic infections may be the real story.
So people had no idea they had Covid. Because their bodies prevented the virus from getting sick. I had no cough, fever, or difficulty breathing.
One study conducted early in the pandemic, when routine testing was common, suggested that more than 40% of cases could be asymptomatic. We stopped tracking the proportion of asymptomatic cases as it has become less common.
Openshaw finds asymptomatic cases “quite fascinating.”
“What removes the virus before it gains a foothold?” he asked.
That’s exactly what Jill Hollenbach, a professor in the Department of Neurology and Epidemiology and Biostatistics at the University of California, San Francisco, is trying to discover.
“Some people have no symptoms at all,” Hollenbach said. “Something is going on at a really basic level of the immune response that will help these people wipe out this infection once and for all.”
Hollenbach’s lab focuses on human leukocyte antigen, or HLA. This molecule is present on the surface of every cell in the body and basically acts like an overzealous watchdog.
HLA always tells the immune system what it finds near the cell. Usually they are harmless bits that should be in the body. The immune system is generally unfazed by this.
HLA can carry things that the immune system cannot recognize, such as viruses like Covid. That’s when it’s supposed to launch the attack.
But HLA’s abilities vary widely from person to person, and Hollenbach needed to find out which version of HLA was particularly good at prompting the immune system to rid the body of Covid.
She turned to the National Donor Program, which has about 13 million people participating. All her HLA types are properly recorded.
The HLA genes are the same that must be matched in patients undergoing organ and stem cell transplants.
Hollenbach’s team then tracked about 30,000 people from that registry from the start of the pandemic until April 2021, when a vaccine was widely available.
More than 13,000 people eventually tested positive. 10% were completely asymptomatic.
“The definition of asymptomatic was pretty strict, not even an itchy throat,” Hollenbach said.
strong immunity, common genetic thread
Her team found a common genetic thread, a gene called HLA-B*15:01. Hollenbach found that people with this HLA version of her were more than twice as likely to get asymptomatic infections. If a person has two copies of the gene he has, the protection is more than eight times stronger than hers.
her research Publish on preprint serverand is currently under review in a peer-reviewed journal, says Hollenbach.
People with asymptomatic infections may also find it helpful to study them in other ways. It suggests an intriguing possibility that it may not exist.
“This is important because that’s what we want to achieve with our population,” Iwasaki said.
Iwasaki suggested that people who are infected but show no symptoms may develop a “strong mucosal immune system.”
That is, when they inhale fragments of the virus, an army of immune cells rapidly gathers in their mouth and nose. .
“This may indicate that these people developed a very strong local immune response that prevented future infections,” Iwasaki said. , it may be possible to determine whether these mucosal immune cells actually retain memories of Covid.
According to Hollenbach, people who have a form of the HLA gene in their immune system also seem to have the amazing ability to remember previous infections, and act quickly when they spot a previous threat. .
Hollenbach believes this is why children have generally escaped the worst consequences of Covid. Their little bodies are already very familiar with respiratory viruses.
“They basically spend years from age one to seven with a completely runny nose,” she said. Always passing by.”
This idea is of interest to other professionals.
“Much work has been done to see if cross-reactive immunity stimulated by the common cold coronavirus could be a factor that makes a difference in how people respond to Covid. We are doing it,” said Openshaw.
That may be why Sue Nowatzke, a semi-retired nurse in Ames, Iowa, is coronavirus-free.
“Ever since I was a kid, I’ve caught all kinds of respiratory crud easily,” said Nowatzke, 64.
Nowatzke last remembered being sick in December 2019.
She has never tested positive despite being repeatedly exposed to Covid while working as a nurse in June 2021.
Her husband Duane, 68, has also never tested positive, though it’s unclear if that’s due to an innate ability to ward off Covid. They say they rely heavily on masking and up-to-date vaccinations.
“They came up with a shot, we got it,” said Duane Nowatzke.
Is Covid Infection Inevitable?
Experts are urging caution as scientists look for genetic factors that could make a lucky few people immune to Covid.
“I never want to say, ‘I’m invincible because I don’t have Covid,'” said Dr. Michael Angarone, an infectious disease specialist at Northwestern Medicine.
Some believe that it is inevitable that sooner or later the entire population will be infected. Masking and vaccines are effective but not foolproof.
“There are very few people left that I know who are uninfected,” Angarone said. “Even people I know who were washing groceries ended up getting infected.”