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Colorado Expert Discusses Studies On Whether COVID Infection Is Enough For Future Prevention

WHEAT RIDGE, Colo. (CBS4) - "Mostly more of comfort," Roy Trujillo said as he showed up at a Stride Community Health vaccination site for a booster COVID shot. The vaccine has worked for him. He got it about four months after getting a case of COVID-19 last year.

"My wife got it, too, and two of my granddaughters," he said.

Fortunately his case was mild. Roy, a retiree at 66, is one of millions now living life after infection with SARS-Co-V2.

"You're going to develop an immune response to that infection and that's going to give you a boost in immunity," explained National Jewish Health's chief medical information officer Dr. David Beuther. "The degree to which you have a boost immunity and how long that last is pretty variable."

The topic is being discussed by researchers all over the world as they try to figure out whether there is enough protection to skip vaccines. Two studies, one early this year at the Cleveland Clinic and another more recently in Israel showed protection among those previously infected. The rate of testing positive for COVID-19 was lower than among those vaccinated. Still, there are a lot of ifs with the studies. The Cleveland Clinic has recently followed up with a statement about its research. They noted it was conducted before the emergence of the more contagious Delta Variant and said in part:

"More research is needed. We do not know how long the immune system will protect itself against re-infection after COVID-19, as our study only looked at individuals over a five-month period, or how well-protected previously infected individuals are against variants. It is also important to keep in mind that this study was conducted in a population that was younger and healthier than the general population."

The study in Israel was later, but experts point out that those who waited longer for vaccination, or skipped it are likely people at less risk than the vaccinated. Not an apples to apples comparison.

"If you were early on in the pandemic getting vaccinated in December and January, you're likely a health care worker, older, compromised ... being very careful. That's somebody that's more likely to get a breakthrough infection. That's also somebody more likely to go and get a test to find out if they're infected," noted Beuther.

The immune system has two very significant parts, the first being antibodies which have typically been the measurement of the body's defenses.

"They're you're kind of beat cops out in the street looking for the perpetrator, they have a picture of the bad guy and you're out there, looking for him circulating around," said Beuther.

But if the blood were filled with antibodies, it would be as thick as molasses. The body also develops long term cell memory that involve B and T cells.

"The T cell is really kind of more I guess the FBI database of criminals. It's there to keep a log of everything you've been exposed to in the past," explained Beuther.

"That memory T cell will say wait a minute, I think we're supposed to fight this guy off and they'll tell the B cell to make more antibodies… pretty soon the police station is going to get activated, they're going to call in the navy and army and you're going to get a bunch of help."

mRNA vaccines were tested for the effectiveness of this deeper cell memory, showing how significantly they were tested said Beuther. In the past, vaccines have been gauged with antibody measurement only. The long term memory is what provides protection for months, years, maybe decades.

But no one is sure yet. Researchers do know antibodies decline with time. That's true for both prior infection and vaccination. But testing has shown variability in antibody production to the virus. But Beuther explains, some people who had mild COVID infections might get less protection.

"Your immune system really might not generate a big response to that, or maybe any response at all. You know, it might see that as not a real threat."

Or those who had severe infections may have their immune response compromised. The vaccines are, for now, a better known quantity and response.

"Many of these studies are observational and they're fraught with complications and they you know they give us good ideas, but they don't tell us a true certain answer to the question."

That's why there's more study needed. There may come a day, said Beuther, when vaccine recommendations are modified for those with prior infections to get only one shot.

"It may even be that if you have the combination of a vaccine and a natural infection, that somehow that's providing more complex view of the virus, so that the immune system can have a more nuanced response. But we really don't have any long term data to suggest you know that that is superior to just vaccination alone."

Roy Trujillo got his booster and left the vaccine site. He was feeling fine.

"Better safe than sorry," he said.

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