Seroconversion rate following HBV vaccination in clinical practice: The role of age and DMT treatment.

HBV screening and immunization is recommended in all MS patients and is mandatory before the start of some DMT. However, studies evaluating the immune response to HBV vaccine in MS patients are scarce. We aimed to evaluate the seroprotection rate following HBV immunization in MS patients and to assess if older age and DMT-treatment influenced seroprotection. We conducted a cohort study between 2016 and 2020 and compared the immune response to HBV vaccine in MS patients under different DMTs and in patients 50 years old or younger and older than 50. We found that patients under non-injectable DMT presented lower rates of seroprotection comparing to patients under injectable DMT's or without treatment. In patients older than 50, although the seroprotection rate was similar to the remaining patients, the antibody anti-HBV surface antigen titers following HBV immunization were lower and patients were more likely to require a 4th dose of the vaccine to achieve seroprotection. Our findings highlight to need to consider HBV immunization in MS patients early in the disease course, in order to ensure a proper immune response to the vaccine.