UC San Francisco researchers discover why some people are asymptomatic when infected with COVID-19

Once a COVID-19 infection sets in, the virus has extreme differences in how it impacts an unvaccinated person’s body.

Throughout the pandemic, novel coronavirus proved to be lethal in some patients.

“(COVID) can attack almost anything in the body with devastating consequences,” cardiologist Dr. Harlan Krumholz of Yale University told Science Magazine.

Other infected patients are asymptomatic, meaning, they never feel sick.

Most studies on COVID, scientifically named SARS-CoV-2, conducted over the past two years have focused on patients who suffered severe symptoms or death.

Looking further into the virus’ complexities, researchers at the University of California San Francisco launched a study focusing on why some people are asymptomatic, KTLA sister station KRON reports.

Jill Hollenbach, a UCSF professor of neurology, epidemiology and biostatistics, conducted a study on a group of 1,400 people. Patients selected for the study were unvaccinated, tested positive for COVID and experienced zero symptoms while infected.

Hollenbach and the research team analyzed each person’s DNA, looking closely at a set of genes called HLA. They found a genetic mutation in HLA genes that fought off COVID so quickly, the person’s body never had enough time to develop symptoms.

And while the mutation was not bulletproof, it raised a person’s chances of remaining asymptomatic times 10.

Hollenbach told KRON, “My lab is interested in a set of genes called HLA. Those genes are pivotal immune response genes. We wondered if certain versions of these genes are more or less effective in helping folks to deal with COVID infection.” 

The study’s hypothesis and preliminary findings were published as a preprint here. Hollenbach said the team is excited for their complete study to be published next month.

Researchers previously wondered, is there a genetic basis for so-called “COVID superdodgers,” people who are exposed to the virus but were never infected?

Hollenbach explained, “There has not been a lot of success in answering that question. Too many complications. But we can ask the question, once someone is infected, why is their disease course different? What is the immunological basis?”

COVID-positive patients who never felt even a sniffle shared a common gene mutation, HLA B 1501, researchers discovered. This gene was especially effective for waging a rapid immune response against COVID-19 using T cells previously generated from common colds.

“I would not call it natural immunity. I would call it pre-existing immunity. We are not crazy about the use of the term natural immunity, because vaccine-elicited immunity is natural too, in a different way,” Hollenbach said.

People with the HLA B 1501 gene were essentially “COVID minidodgers” — they didn’t dodge the infection, but they dodged feeling sick.

NPR wrote, “Hollenbach and her colleagues demonstrated that, with a specific mutation in HLA, some people have T cells that are already pre-programmed to recognize and fight off SARS-CoV-2. So there’s no delay in generating COVID-specific weaponry. It’s already there.”

Hollenbach said that best news is that the mutation is common — about 1 in 10 people have it.