Sporadic late-onset Alzheimer's disease (AD) is the most frequent cause of dementia associated with aging. Due to the progressive aging of the population, AD is becoming a healthcare burden of unprecedented proportions. Twenty years ago, it was reported that some indole molecules produced by the gut microbiota possess essential biological activities, including neuroprotection and antioxidant properties. Since then, research has cemented additional characteristics of these substances, including anti-inflammatory, immunoregulatory, and amyloid anti-aggregation features.
Hepatitis B (HB) vaccination plays a significant role in controlling HBV infection. Different immune mechanisms govern anti-HBs acquisition, titer, and maintenance. Host pre-vaccination immunological status could be targeted for vaccine efficacy.