@rits & @irene5 Here is the response I received from my go-to RN on the vaccine – she works in the ER and on the TeleMed & Covid lines for a major health care provider, and consults directly with the Covid specialists there. This is how they respond to vaccine questions:
"Some people don't have strong immune response to 1st or 2nd dose or both. Some people have strong response to 1st and not 2nd. Some people have strong response to 2nd and not first. Some people have strong reaction to both. The level of immune reaction that you can feel/see/measure has no impact on the vaccine's ability to protect you. Your body has received the info and build the antibodies.
Being tested for antibodies is not recommended. The test is expensive, and no medical decisions will be made from having it done no matter what the result is so most insurance companies will not pay for it."
That said, the vaccine manufacturers are also monitoring the early recipients to see when the immune response and/or antibodies begin to fade. That will be the key to determining if or when Covid vaccine boosters will be recommended, and whether they will need to "tweak" their formula to cover virus variants.
Based on all of the above, we need to realize that the world is not a perfect place, there is no perfect vaccine, nor any permanent preventative measure against all illness, disease and risk. I wear my seat belt because it reduces my risk of severe injury or death in a car accident, I clean, store & cook my food properly to reduce the risk of food-borne illness, I exercise to keep my body as strong as possible, I take prescribed meds to reduce the risk of my diseases progressing, I get preventative health screenings to reduce my risk of dying from cancer, and I get vaccines to reduce my risk of severe illness or death from infections. Is my life 100% risk free? No, but I still plan to live well & enjoy it.