
Originally Posted by
Mofro261
Ok. So lets break this down again. Natural infection causes natural immunity.
But are all infections the same?
No, not by a long shot.
Hence, natural immunity following natural infection varies widely in a population of convalescent COVID-19 people. How much? Between 5 and 6 orders of magnitude. If those words don't make sense it means from natural infection, the amount of a measurable metric, like how much antibody was produced, varies up to 100,000-1,000,000x between people after infection. Some have a massive amount, some end up with levels below detection. Host genetics, environmental factors, basal levels of inflammation, immunosupression, medications, age, and general health markers all contribute. So do severity of disease, location(s) of where live virus has reached in the body, and duration of infection/symptoms also contribute to variance in natural immunity. More severe disease leads to higher responses. In the process of setting up natural immunity, it's also possible to set off an over-reaction that is detrimental to the body where the immune system attacks ones own tissues. Hospitalizations, increased at least 2x with the Delta strain that also causes increased disease severity in the very young, and deaths, focused in older populations but also scattered through the young and healthy, are side effects of natural infection leading to natural immunity.
Vaccination we know the dose, we have a pretty good idea about the duration of the response, but all those genetic and environmental factors still come into play. Despite that, vaccinated people show less variability, more on the 1,000-10,000 fold differences across a population. The very low end of the response and the very high end responses seen in natural infection are missing. It's a bell shaped curve, natural infection can give equal to, better than, or much worse than, an immune response such as neutralizing antibody or t cell recall responses. That's at a level of magnitude, or how much.
Generally speaking natural infection can increase the breadth of the immune response, primarily due to prolonged antigen presentation and the adjuvant (danger) signals that help shape both t and b cell development, given it's from a live virus that has full infectious potential and the total sum of the antigenic potential. This increased breadth can aide (increased t cell help, increased differentiated memory b cells ) or impede (development of non-productive t cell or non-neutralizing antibody targets to non-Spike antigens, antibody directed enhancement of infection). This is "how many." Ie if I need 100 neutralizing antibodies to achieve a level of protection, I can do it with 10 different antibodies all with a level of 10, 5 with a level of 20, or one antibody at a level of 100. But if I encounter a mutated strain, I'm more vunerable in the last case if there is not enough breadth in the response even if there is sufficient magnitude that was generated.
We make the assays to measure some of these immune "correlates". All of the assays are extensively tested on actual samples that we recieve. This is the variability we see, in convalescent serum samples and vaccinated samples.
The argument has always, always, been is "what is the best way to achieve immunity". There are ZERO immunologists suggesting natural infection with live virus is the preferred route for dosing.
Not "is natural immunity superior or inferior to vaccine mediated immunity." When the average cost of a hospital stay is $50,000 vs a couple vaccine doses at $20 each, and with transmission cycles leading to wave after wave of infections without an approach to herd immunity, there really should be no arguement at all.
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