[oldalum]

yes, it's simply unknown at this point, but no reason to lose sleep yet. These people with low post-infection titers may truly be immune. They do have memory cells that might generate a protective antibody response, or they might just be able to fight off the infection with low levels of antibodies. Or, giving them the vaccine might generate a big, protective response. They are a different population than those who have never been infected. For the latter, vaccine developers often link molecules to the vaccine antigen(s) that augment the immune response (called adjuvants), in order to provoke an immune response strong enough to be protective.

[oldalum]

yes, it's simply unknown at this point, but no reason to lose sleep yet. These people with low post-infection titers may truly be immune. They do have memory cells that might generate a protective antibody response, or they might just be able to fight off the infection with low levels of antibodies. Or, giving them the vaccine might generate a big, protective response. They are a different population than those who have never been infected. For the latter, vaccine developers often link molecules to the vaccine antigen(s) that augment the immune response (called adjuvants), in order to provoke an immune response strong enough to be protective.