systems response to both SARS-Cov-2 and the various vaccines.
I am having a discussion with someone about the human immunological response to SARS-Cov-2.
The discussion is over which is better, the post infection immunity or vaccine induced immunity. He believes the Israelis study as well as the Qatar study show that post infection immunity is better and more long standing than vaccine induced immunity.
That's contrary to most other vaccines, except mumps, where vaccine induced immunity is more even and of higher quality.
Here is his explanation. Tell what I'm missing.
"When an individual is exposed to a respiratory pathogen, the first line of defense is IgM mucosal immunity. A vaccinated person typically does not get this immunity, because the antibodies are first encountered in the bloodstream, not external mucosal linings. This is one reason why vaccinated individuals tend to have as much antigen on their mucosal swabs as unvaccinated, previously uninfected individuals and more than a naturally immune person. Hence, they can still be vectors of disease through mucosal spread.
The second line of defense is humoral immunity. This is what we also know of as IgG antibody induced immunity. Antibodies are created in order to defeat the acute illness. It takes a while for the human body to ramp up those antibodies from scratch, so during that time a patient is ill. The current Covid vaccine appears to do a decent job of inducing humoral immunity (hence the lessening of symptoms upon subsequent exposure to the live virus). However, this humoral immunity is primarily targeted toward the alpha spike protein, not the other variants. Therefore, we see a lot more breakthrough infections in vaccinated people than we do in naturally immune people, because naturally immune individuals (as with traditional dead/attenuated viral vaccines) were exposed to the entirety of the virus, not just the specific alpha spike protein. This may also be one reason why forthcoming vaccines like Novavax, which use more traditional technology, are thus far proving to be more effective in trials.
The third line of defense is where our long-term immunity comes from, specifically cell-mediated immunity. Over time, circulating antibodies in the bloodstream naturally decline (which is why the argument that we don't know how long antibodies last is irrelevant - they aren't supposed to circulate forever). This is our memory T- & B-cells, killer T-cells, etc. During the first exposure, memory cells are created. Subsequent exposures to the same antigen stimulate these cells to immediately attack the antigen/infected cell & produce antibodies, neutralizing the virus before it can cause symptoms. It is as yet somewhat unclear as to why the current vaccines require boosters and fail to be very productive beyond 3-6 months. One theory is that these vaccines, while doing a fairly adequate job of inducing temporary humoral immunity, do not do as well at stimulating long term cell-mediated immunity; this may be due to the fact that the immune system is not being exposed to the entire virus. In a natural immune response, however, these T cells are stimulated and, for the vast majority of pathogens and how we have understood the immune system to work for decades now, cell-mediated immunity usually lasts a lifetime in a healthy individual."
There are small aspects of his explanation that don't jive with my understanding. Enlighten me please.
I am having a discussion with someone about the human immunological response to SARS-Cov-2.
The discussion is over which is better, the post infection immunity or vaccine induced immunity. He believes the Israelis study as well as the Qatar study show that post infection immunity is better and more long standing than vaccine induced immunity.
That's contrary to most other vaccines, except mumps, where vaccine induced immunity is more even and of higher quality.
Here is his explanation. Tell what I'm missing.
"When an individual is exposed to a respiratory pathogen, the first line of defense is IgM mucosal immunity. A vaccinated person typically does not get this immunity, because the antibodies are first encountered in the bloodstream, not external mucosal linings. This is one reason why vaccinated individuals tend to have as much antigen on their mucosal swabs as unvaccinated, previously uninfected individuals and more than a naturally immune person. Hence, they can still be vectors of disease through mucosal spread.
The second line of defense is humoral immunity. This is what we also know of as IgG antibody induced immunity. Antibodies are created in order to defeat the acute illness. It takes a while for the human body to ramp up those antibodies from scratch, so during that time a patient is ill. The current Covid vaccine appears to do a decent job of inducing humoral immunity (hence the lessening of symptoms upon subsequent exposure to the live virus). However, this humoral immunity is primarily targeted toward the alpha spike protein, not the other variants. Therefore, we see a lot more breakthrough infections in vaccinated people than we do in naturally immune people, because naturally immune individuals (as with traditional dead/attenuated viral vaccines) were exposed to the entirety of the virus, not just the specific alpha spike protein. This may also be one reason why forthcoming vaccines like Novavax, which use more traditional technology, are thus far proving to be more effective in trials.
The third line of defense is where our long-term immunity comes from, specifically cell-mediated immunity. Over time, circulating antibodies in the bloodstream naturally decline (which is why the argument that we don't know how long antibodies last is irrelevant - they aren't supposed to circulate forever). This is our memory T- & B-cells, killer T-cells, etc. During the first exposure, memory cells are created. Subsequent exposures to the same antigen stimulate these cells to immediately attack the antigen/infected cell & produce antibodies, neutralizing the virus before it can cause symptoms. It is as yet somewhat unclear as to why the current vaccines require boosters and fail to be very productive beyond 3-6 months. One theory is that these vaccines, while doing a fairly adequate job of inducing temporary humoral immunity, do not do as well at stimulating long term cell-mediated immunity; this may be due to the fact that the immune system is not being exposed to the entire virus. In a natural immune response, however, these T cells are stimulated and, for the vast majority of pathogens and how we have understood the immune system to work for decades now, cell-mediated immunity usually lasts a lifetime in a healthy individual."
There are small aspects of his explanation that don't jive with my understanding. Enlighten me please.