Above is our test of my blood's Covid 19 antibodies (IgG class) at 3 months after my 2nd dose of Pfizer vaccine. Marked with the black dot. The red line to the right is a control line.
Below is my test done today, now about 5.7 months after full vacvination.
As you can see the relative concentration of my antibodies to the spike protein of Covid 19 is still easy to detect but is about half of what I had at 3 months.
Now even if my antibodies fade away completely, I will likely have resident immune system clonal cells that are ready to detect and respond more quickly to a Covid 19 infection than I would have prior to being vaccinated. However, in time, the number of those cells will also decrease.
So we should expect that a yearly vaccine shot to Covid19 will be routine medicine just as the flu shot is too. Generally, our human immune system does not remain primed for more than 6 months against corona-type viruses, which is the class of virus that Covid 19 belongs to. Many coronaviruses are actually cold viruses and we already know that it's possible to get a full-blown cold more than once from the same coronavirus strain within a single winter because coronaviruses trigger a shorter lasting immunity.
The viral RNA polymerase that makes copies of the Covid 19 RNA within infected cells has an error rate of 1/10,000, and the genome of Covid19 is about 30,000 bases long. Thus each new virus made in one of our infected cells has an average of 3 mutations. That is three bases different from the virus that infected the cell. That means that almost all 3,000 to 5,000 copies made in one infected airway cell are all mutated, changed, different from the original infecting virus. That is how viruses change, adapt, and evolve. Most of the mutations will not make much difference, some will make the virus less efficient, but some can make the virus replicate faster and also bind faster and stronger to our airway cells.
That is why variants like Delta occur and the virus will have opportunities to become even worst if we have large regions of mostly unvaccinated persons. Mutations have changed the Delta variant's spike protein and just one changed link in that protein makes it bind to and infect cells faster than the virus at the start of the pandemic.
As a molecular biologist with expertise in gene expression, genetic diseases, and RNA and DNA polymerases, I am concerned.
I will get my Covid-19 booster as soon as I am eligible.
PS. I got my flu shot last week and have done so every year for over 15 years. I have not had the flu in that time.