Reinfection, when it occurs in a healthy individual, the antibody titer acquired from the previous infection, should neutralize the antigen provided there is the same strain and probably occurs within the period of ? decay of the immune response ( It is not yet clear how long the antibody production lasts).
If the infection is from a mutant strain then one has to see whether the immune cells' memory works or fails.
It has been observed that reinfection is happening in individuals in people who have been vaccinated with both the doses of the vaccine....we need to do a post vaccination antibody titer of all these individuals to ascertain the protective level of these antibodies and determine a level of protection.