A COVID mystery: Some people never get sick even after being exposed to the virus

SEATTLE (KOMO) — A big mystery of the COVID-19 pandemic that researchers are baffled by is that some people are exposed to the virus but never get sick even as others are diagnosed with it multiple times, despite being vaccinated.

Researchers say figuring out why that happens is an important question, and they're working to find the answer.

Lakewood Police Department Lt. Andy Gildehaus was working specialty patrol in Washington state when the pandemic began.

"Being in a business that's 24/7/365, you don’t have that option to say, 'Well we’re gonna shut it down for a while and let it pass by,'" he said.

Chief Mike Zaro couldn't tell his officers to work from home.

"We still had 911 calls and had a job to do," Zaro said. "So, that’s been the balance that’s been tricky from the beginning."

Like other first responders, they took all possible precautions, but there was no avoiding COVID-19.

The department suffered several small outbreaks, and some people, including the police chief, got sick.

"Twice as a matter of fact. I’m a two-timer," Zaro said. "The first time was December of 2020, so before the vaccine was around, and really in the depths of the lockdown and precautions. I was taking all reasonable precautions, as much as anyone else, and there was no way of knowing where I got it."

Zaro's second illness came a year later during the Omicron wave.

But Gildehaus? "Without a doubt I’ve had exposure to people with COVID," he said. "I have never gotten COVID. My wife has gotten COVID. Two of my sons have gotten COVID. But I have been very fortunate and I’ve never gotten COVID."

Gildehaus and Zaro are both fully vaccinated. Both are healthy, and both followed guidelines.

Outcomes like theirs are at the heart of the research in Dr. Michael Gale, Junior's lab at UW Medicine. Gale is a professor of Immunology and an expert on innate immunity.

While we develop active immunity to a virus from infection or vaccination, Gale says some people haven't gotten sick thanks to innate immunity.

"Every cell in our body has the ability to mount an immune response against a virus," Gale explained. "This is at the molecular level. Not T-cells, not antibodies. It’s a molecular response that’s geared to fight off the virus. We collectively call this the innate immune response. The local area that sees the virus first mounts an innate immune response that presents the expression of genes, whose job it is to turn on and shut off the virus so it won’t spread. This is what protects the majority of people from developing severe symptoms and only having mild disease." Or, not getting sick at all.

His team of 15 scientists is working to harness that innate immune response to develop new therapeutics.

Dr. Michael Davis is a senior scientist in the Gale lab. Davis said they're looking for the specific genes that turn on that innate immune response. "It’s a lot like looking at a car engine and figuring out what makes it work. You take one piece out, does it still run. We can do the same thing with the innate immune response. Take out one gene, see if it still runs. If it doesn’t, we know that’s important for the whole process to work," Davis said.

They're learning more each day, but solving the mystery will take time. Gale said they have some therapeutics nearing phase one clinical trial, while others are at least five years away.

In the meantime, they point out the virus is continually evolving. They say even people who haven't gotten sick yet should get vaccinated.

" It's not a zero-risk game," Davis said.

That's something police know every day.

While Guildehaus might have a genetic advantage over COVID, Chief Zaro's focus is on keeping his officers safe from all threats and hazards.

"I’m no more concerned today than I was a couple years ago," Zaro said. "COVID is just on more thing that we have to be mindful of."