https://www.israelnationalnews.com/News/News.aspx/299415
COVID antibody levels decline significantly two months after injection of the second dose of the coronavirus vaccine, a new study shows.
But some experts say the study is not necessarily cause for alarm, noting that similar declines are observed with antibodies for other viruses, and that antibodies make up only part of the body’s immune system.
In an interview with according to Channel 12, Dr. Greenfield said the long-term effectiveness of the vaccine remains unknown, but added that there is no reason to believe the decline in antibodies indicates a loss of immunity.
A couple of considerations
ReplyDelete1) Antibody memory is as important as having active circulating antibodies. Early on it was noticed that some people who got coronavirus barely got sick. One explanation turned out to be that they had been previously ill with similar coronviruses and the memory of those infections allowed quick antibody responses to this one. So if active levels drop, it's okay because if infected, the body can ramp up a new response within a day.
2) This is why rapid vaccinations followed by massive gatherings is important. Everyone is vaccinated so there's general protection but then they also get the virus and produce additional responses which strengthens future immunity. Getting vaccinated and continuing precautions would prevent this.
The media has also fearmongered about antibodies post-Covid infection "dropping dramatically!!!!" after a few months post-infection. All this talk ignores important facts:
ReplyDelete1. The standard course of events in ANY infection is that serum Antibody levels peak during the infection (not even after it is cleared, but during the tail end of the infection they are already declining!) and then decline steadily from that point forward until they reach a steady state level. That steady state level will either be above the threshold required to prevent a new infection (a "re-infection" aka breakthrough infection), which would mean lifelong immunity from further infection, or below that threshold, where a breakthrough infection is possible.
2. In the case that a breakthrough infection does become possible, whether it's after 1 year, 2 years, or 10 years, (We don't know yet, and no one knows what the threshold is, but antibodies and neutralizing antibodies have been shown to persist at pretty high levels >9 months post covid infection so far, and reinfection has been a rare phenomenon), MEMORY B CELLS will turn on immediately in response to the breakthrough infection and immediately ramp up synthesis and secretion of those same antibodies that were in the blood stream but went away. And to much higher antibody levels than they reached in their peak concentration during the first infection. This won't take 14 days as in the first encounter with the pathogen to derive and then proliferate such antibodies, it will be immediate once innate immunity is breached and an infection is seeded.
1. The mild infections are most likely not due to Cross reactivity but rather a fine-tuned immune system that reacts more quickly. There is a range of time (typically 10-14 days, but can be even slower) to switch on adaptive immunity in response to a new pathogen. Those with more severe covid seem to be taking longer to turn on their antibody response than those with mild disease. Cross reactivity from other pathogens has been nil, and no good direct evidence has been demonstrated yet that it meaningfully impacted the pandemic. But cross reactivity, if any should exist, would be from T cells, not antibodies or the b cells that make antibodies. Very few people on the planet have had SARS before and would therefore have cross reacting SARS antibodies (a select few of convalescent SARS antibodies do act on SARS cov2). Only 8000 people got SARS.
ReplyDeleteYou are correct that memory b cells are important and the circulating antibody concentration going down does not indicate that immunity is lost. It is the typical course of events after an infection (or a vaccination). Where they END UP is what matters.
There is also some T cell immunity (and therefore t cell memory) induced by the pfizer and moderna vaccines from what I've read.
2. The booster shot is already accomplishing what you suggest a mass gathering would accomplish. The capacity to be infected again after the 2nd dose is diminished to such a large degree that your idea is counterproductive. 80-90% of the people you are artificially trying to get infected are incapable of being infected anyway, and among the other 10-20% will be included the rare exceptions of people who got vaccinated but did not produce a sufficient or correctly targeted immune response and have gained no protection. These rare cases will exist. (Some fraction of the 10%). Those people would be harmed by purposely infecting them.
Most of these 10-20% getting infected would be getting an asymptomatic infection in either case, so going about life as normal would make sense, but going out and purposely trying to get infected does not.