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Comment by TheBlight | Hacker News Reader

If "update" refers to updating the mRNA message to create the new S' protein in order to prompt your immune system to produce S' abs then I think you will be disappointed. This sort of "update" will almost certainly trigger a recall of the former S abs due to immunogenic imprinting. See also: https://pubmed.ncbi.nlm.nih.gov/28479213/

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Does that mean the people who got vaccinated won't benefit from a new vaccine, but unvaccinated people can?

Yes. And there is a small possibility that something even worse happens for those previously infected/vaccinated called antibody-dependent enhancement (ADE). ADE occurs when the antibodies generated during an immune response recognize and bind to a pathogen, but they are unable to prevent infection. Instead, these antibodies act as a “Trojan horse,” allowing the pathogen to get into cells and exacerbate the immune response.

The worst case with a new covid strain would be if people who were vaccinated by a previous vaccine or infected by an older strain experience antibody-dependent enhancement after being infected with the new strain. This is where the body recognized the new strain as the old and starts producing anti-bodies. These anti-bodies actually assist the new strain in infecting your cells, making the disease worse.

ADE has not been detected with any covid strains/vaccines so its not something to worry about for now but who knows what may happen in the future. I've been keeping my eye out for any news of ADE with any of these new strains.

Certain viruses like dengue fever can be much worse if you had previously caught a different strain due to ADE.

https://www.chop.edu/centers-programs/vaccine-education-cent...

Since the current vaccines are based on recognizing the spike protein, and since this South African (Nu?) variant has many mutations on the spike protein, what are the odds that a vaccinated person's immune system would recognize the mutated spike protein as being the same as the original one?

No idea. Time will tell but a high number of mutations is not ideal.

I didn’t know about any of this. Thanks all for your comments.

Now I’m getting some bad February 2020 déjà-vu reading this current thread about flights from Gauteng:

https://twitter.com/AdamJSchwarz/status/1464150235714932742?...

It's not surprising people are unaware of this. Part of the pitch was that these vaccines could be updated as easily as software and be rolled out quickly to combat whatever variant.

If you trigger a memory response why would it matter if it was recalling a different similar protein? Wouldnt your immune system also remember and respond to a real pathogen, suggesting that the orginal vaccine was sufficient? In what world do you identify a pathogen but the fail to respond to it? Its not as if your body responds significantly differently to distinct illnesses.

Perhaps my understanding here is too cursory but this claim is pretty extraordinary for what I know.

Your immune response can be triggered by a specific epitope but provide a less than optimal response. I'm not pulling this out of my ass. Moderna tried making a beta strain specific booster but noticed the original wild strain antibodies elicited from previous vaccination were activated. See also: https://www.cell.com/trends/immunology/fulltext/S1471-4906(2...

I suspect this is part of the reason why we never saw an "update" for the delta variant.

What is a less than optimal response? Partial binding?

Bind but not neutralize.

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