Did you get COVID but never feel sick? New study hints at why
As the coronavirus emerged, so did a mystery: Why did some who got infected never develop symptoms?
One likely explanation is it may be a person’s lucky genes.
A new study in the scientific journal Nature suggests people with a specific version of a gene were far more likely to experience an asymptomatic infection than those without.
The relevant set of genes is known as the human leukocyte antigen, or HLA.
“This is the first time where, in a really rigorous and robust way, anybody has shown that there is a clear, definitive genetic underpinning to asymptomatic disease (from the coronavirus) — not all asymptomatic disease, but some subset of people who stay asymptomatic,” said UC San Francisco neurology professor Jill Hollenbach, a co-author of the study.
Hollenbach and other researchers recruited some 30,000 people for the study — all of whom already had genetic data on file because they registered as potential bone marrow donors with the National Marrow Donor Program.
Scientists asked those individuals to join the COVID-19 Citizen Science study, organized by researchers at UC San Francisco, and to use a smartphone app to track their coronavirus test results and symptoms.
Researchers had a significant sample size of coronavirus-positive patients with European ancestry to generate meaningful data; there were too few test-positive participants of other ancestries for those results to be significant.
Scientists identified about 1,400 people with European ancestry who had a confirmed positive coronavirus infection in the first year of the pandemic, and all were unvaccinated because shots weren’t yet available.
Of that group, 136 were asymptomatic, or roughly 10%. Reasons symptom-free people were tested could include the nature of their job, such as being a health care worker undergoing routine testing, or perhaps their family member was infected and they were considered exposed to the virus.
Irfan Khan, Los Angeles Times
Commuters wear masks during a surge in the COVID-19 pandemic on Dec. 6, 2022, in Los Angeles.
Significantly, the scientists found that people who had a version of the gene called HLA-B*15:01 were more than twice as likely to remain asymptomatic compared with those who didn’t, Hollenbach said.
And if a person had two copies of the version of this gene — one from each parent — “they were 8½ times more likely to have remained asymptomatic,” Hollenbach said.
“I’ve been involved in these HLA disease association studies for my whole career, and we were pretty stunned, actually. That was a really strong effect,” she said.
The findings follow smaller studies that suggested genetics were potentially associated with asymptomatic coronavirus infection.
Just to make sure what they were seeing was real and not something peculiar about their particular study group, the scientists also reanalyzed data in a British cohort and conducted a genetic analysis of another set of patients studied by other UC San Francisco researchers.
“We were able to replicate that same finding,” Hollenbach said. “At that point, we were feeling really confident that this was a real effect.”
The new study also suggests why this particular version of this gene may have helped some avoid the ravages of the worst pandemic in modern history.
One reason why the coronavirus was so deadly was that it was novel: Since it had yet to circulate, people hadn’t been exposed and many lacked immunity to combat it.
For people with the special version of this gene, the study suggests their immune systems were somehow more readily able to target the pandemic coronavirus, officially known as SARS-CoV-2.
After previous skirmishes with other run-of-the-mill, non-pandemic coronaviruses — the culprits behind the common cold — people with this version of this gene somehow developed the tools to better armor themselves against the pandemic strain of the coronavirus that began spreading in late 2019. There are four strains of seasonal coronaviruses that are typically responsible for 15% to 30% of respiratory tract infections annually.
Other scientists previously suggested certain people may have had some degree of immunity to SARS-CoV-2 because of their bodies’ previous experiences with seasonal coronaviruses. With this study, scientists took the idea to another level.
To make this determination, the study’s authors took samples of T cells — an important part of the body’s immune system — collected years before the pandemic began and introduced them to pieces of SARS-CoV-2 in a laboratory setting. The lab data show that the T cells of people with this particular version of the HLA gene managed to recognize these pieces of SARS-CoV-2 and react in a protective manner.
Having this version of the gene “is the key element to having this very effective preexisting immunity,” she added.
Hollenbach said research is underway to do a similar analysis specifically for people of non-European ancestries.
The study has more than three dozen co-authors, with contributions from scientists around the world. It does not suggest B*15:01 is the only explanation for why certain people were asymptomatic. Further research could unearth additional factors, including non-genetic ones.
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Did you get COVID but never feel sick? New study hints at whyCanva
Physician burnout is at an all-time high. According to the American Medical Association, 62.8% of U.S. physicians reported at least one symptom of burnout, which includes emotional exhaustion, depersonalization, and reduced feelings of personal accomplishment.
The COVID-19 pandemic certainly exacerbated this trend. Studies show that factors such as inadequate personal protective equipment and excessive patient volumes were linked with higher incidences of burnout, but this phenomenon long predates 2020.
Occupational burnout among workers in the health care industry is consistently higher than that of workers in other fields. This is in part attributable to the nature of the health care work environment, frequently characterized by staffing shortages, difficult ethical situations, patient incivility, and heavy workloads. Such factors can lead physicians to experience workplace stress, alcohol abuse, and suicidal ideation at higher rates than the general population.
But burnout affects more than just physicians themselves. In fact, physician burnout can impact patient health outcomes as well. Physicians experiencing burnout are more likely to leave their jobs—disrupting patient continuity of care—and make medical errors when providing treatment. However, workplace environments can be strategically designed to mitigate burnout, and additional research and initiatives are underway.
Consulting industry reports, surveys, research, and government resources, DocBuddy looked at the current state of physician burnout following the COVID-19 pandemic.
CanvaPhysician burnout is at an all-time high. According to the American Medical Association, 62.8% of U.S. physicians reported at least one symptom of burnout, which includes emotional exhaustion, depersonalization, and reduced feelings of personal accomplishment.
The COVID-19 pandemic certainly exacerbated this trend. Studies show that factors such as inadequate personal protective equipment and excessive patient volumes were linked with higher incidences of burnout, but this phenomenon long predates 2020.
Occupational burnout among workers in the health care industry is consistently higher than that of workers in other fields. This is in part attributable to the nature of the health care work environment, frequently characterized by staffing shortages, difficult ethical situations, patient incivility, and heavy workloads. Such factors can lead physicians to experience workplace stress, alcohol abuse, and suicidal ideation at higher rates than the general population.
But burnout affects more than just physicians themselves. In fact, physician burnout can impact patient health outcomes as well. Physicians experiencing burnout are more likely to leave their jobs—disrupting patient continuity of care—and make medical errors when providing treatment. However, workplace environments can be strategically designed to mitigate burnout, and additional research and initiatives are underway.
Consulting industry reports, surveys, research, and government resources, DocBuddy looked at the current state of physician burnout following the COVID-19 pandemic.
