COVID researchers discover why some people are asymptomatic

[berkeman]

https://www.kron4.com/health/corona...rs-discover-why-some-people-are-asymptomatic/

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.

Dr. 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 KRON4, “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.

 

[DaveE]

Interesting that this preprint is over a year old, the first version from May 2021, I believe. The same authors wrote this review article more recently, although I have only skimmed it. So, I guess in the virology and immunology world this is older news.
https://www.sciencedirect.com/science/article/pii/S0952791522000255

 

[morrobay]

People who have been exposed but not infected. And those infected but asymptomatic are two different things.This paper gives an explanation for exposure without infection:https://www.sciencemediacentre.org/...-cells-and-the-immune-response-to-sars-cov-2/

 

[DaveE]

People who have been exposed but not infected. And those infected but asymptomatic are two different things.This paper gives an explanation for exposure without infection:https://www.sciencemediacentre.org/...-cells-and-the-immune-response-to-sars-cov-2/

I don't read this paper that way. I think they are really only talking about infected but asymptomatic. There is hardly any way of documenting exposure without infection unless you do a challenge trial, which no one will do. If your T-cells are activated (B-cells too) at any detectable level then you must have been infected. An uninfected person will have no measurable immune response. I'm referring to viral replication of SARS-COV-2, not COVID disease. I think they are referring to people that had an immune response to SARS-COV-2 but didn't get COVID. Sorry to nitpick about semantics, but I think it's really important for the public understanding of infectious disease to get the terminology right.

 

[Bystander]

hardly any way of documenting exposure without infection

Huh?

 

[morrobay]

I don't read this paper that way. I think they are really only talking about infected but asymptomatic. There is hardly any way of documenting exposure without infection

Let's define infection with sero conversion , antibody production. A previous infection with one of the other four coronaviruses can confer cross reactive immunity to SARS-CoV-2.So that would be a cases of exposure without infection. Ie the viruses were cleared and infection aborted. Documented exposure without infection has been shown by prolonged infected family member contact that did not infect other members. As well in hospital settings.Just the first paragraph in this link is very unambiguous regarding exposure without infection: Infection aborted. https://www.nature.com/articles/s41586-021-04186-8

 

[morrobay]

And furthermore this is a screenshot from the link in the OP above where a very clear distinction is made between exposure without infection and infected asymptomatic.

 

[morrobay]

I don't read this paper that way. I think they are really only talking about infected but asymptomatic.

Maybe misunderstandings: The link in post#1 is about infected but asymptomatic. The paper in link in post#3 is about exposed but not infected. That is the first group have SARS-COV-2 antibodies. While the latter group do not.

 

[DaveE]

OK, granted, it's a bit of nitpicking semantics. And this whole diversion isn't that pertinent to the science here.

But I read this* as a transient SARS-COV-2 infection without contracting COVID-19, and in a specific population, without the production of antibodies. There are many parts of the immune system (none of which I actually understand, LOL) besides B-cell antibodies, like the T-cells they discuss here.

I base this mostly on the first sentence in the paper (not the press release):
"Individuals with potential exposure to severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) do not necessarily develop PCR or antibody positivity, suggesting that some individuals may clear subclinical infection before seroconversion."

So "potential exposure... suggesting... subclinical infection before seroconversion"
BTW, I wonder if they really meant "without seroconversion"?

* Yea, actually, I haven't read the paper, the beginning is pretty clear about what the authors think about infection.

PS: Kudos to Nature for not putting this behind their paywall.